université de poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* +...

26

Upload: others

Post on 23-Aug-2020

3 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

������������� ��������� ������� ��� � ���� � ����� ����� �"!$#� ���%��� � ��� ��� �&� � '� ��� � ��� � ���� �(� � ����)*� � ����� �+����� �,.-0/21436587:9<;>=&?@365BAC,*D+E+FHGJILK'EMONQPSR�TVUXWYP[ZQ\TO]_^�UYP`Wbadc�egfihkjOUYPlZYm<no\TpZqPSrkeQTLTpZLst\Tvu�nw\TVZYUqPSTxjxySz_\Tv{QUqPSrkeQT�hk|<}L~k�&���LUqWq^���@a�n�^�Ply��@{<^�fQeQySTvWq���8�pySPS�Q��TVUv� TvN<WV� ��U���/��k;O� �/>�����$����k��� �¡ �¢ ��£q¤¥� ¢V �¦ �i§�� �_¨ £ª©  «�� � �k¬t­ ¨g¢�¨ ­  �®� ¢ �k¬t¯°��± ¢t²J³�´¶µq·�¸� ®± · �k¬   ± � ­&� ¢ ¯6¬¹£���­ ¨ £ � �º­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � � �.� ±6£�£ª��¼ ��� � �*�¹�� � ±¶©   ± � �­k� ¢v¢ �&¬�¯½� �6�_¨�� ­k� � ��¾ ¨ ­k»2±6�  v¿pÀx¨�� §i£ ¨��¶� ¬ ¨�Á �&­C£��t§ ¢ �i±¶¯°� � �k¬ ��&£ ��k��� �¡  ¬�© �«¿Á � ¢ ¬�©ªÂ6£��&¬ � ¤¥± � � ¨ £�§ ®�& ¢ � ®¨'� © Á ©�¬�©ª� � ­k� �¡ �¢�¨ £ª� � � � ©���� � ¬v©�� � #Äà ¬v± ¢�·Å¶¨ © � ¬�©»2±6�Æ£��  �¢�¨�� ¬VÇ0� ¢v È� �&¬º© �¡ «��k§ ¢�¨ £ª�k¬É� ¢ Â6©  �¨ £��&¬�� �¡ �¢ �Æ£��k¬ � �&±«Ê+§ ¢ �i±6¯½�k¬&¼ËC9QÌÎÍO?½Ï@?@5O36-0Ð0ÌÒÑÓ9</�-03¶Ì�Ðb?@5>ÔX?_9.Õ<ÍO3¶9<3_Õ�ÌÎ/¡9g��?@5ÖÌÎÍO/×-0Ð05O/�3«9*Ï_9g?@;xØ

?«Ù½/¡9.3Ú-0?:Õi36-¹ÛL/2-b7Ö?½Ô�ØH?½�kÐdÌÎÐdÙ½/�Õ<ÍO3¶9<3_Õ�ÌÎ/¡9<Ðb�&ÌÎÐbÕ,wÜ���Ì�9<3_Õ�ÌÝ�BÞ �߯ ¢ � Á �  �¦ �Ú� ¢v �¦ �i§i� �6¨ £�©  áà⢠�k£ ¨<  ©�� � ¬.Ç0� ¢ ­ ¦_¨�¢�¨ ­   � ¢ ¬ã��DzJ³�´¶µq·�¸�ä ©  �¦�·å¨ £ª�«­ ¨ £xæ_�k£ � ��ÇH¯°��¬�©   © Á ��­ ¦_¨�¢�¨ ­   � ¢ ©ª¬   ©�­�¼tçȬ�© � §  �¦ ©ª¬ Å°ä ��k¬  è¨ Â6£ª©�¬ ¦�¨ ¾ ¨ ­&»2±6�  V¿pÀx¨�� §i£ ¨��6� ¬L­k� ¢v¢ �&¬�¯½� �6� � � ­k� ä ©  �¦' �¦ �¹§ ¢ �i±6¯'��Ç_© �¡Á � ¢v V¿©�Â6£ª�º�&£��&�o� �2  ¬���Ç ¨ ­k� �2 �¢�¨ £ � © Á ©�¬v©�� �w¨ £�§��k ¢�¨ ��Ç � ©���� � ¬�©�� � #Äà � Á � ¢�·�Ŷ¨��6� �¦ �  �¢�¨�� ¬VÇ0� ¢ ��ÇL� ¢ ¶©  è¨ £Ä© �¡  �k§ ¢�¨ £�¬É½�  áä �k� �× �¦ �k¬��  áä �o§ ¢ �i±6¯6¬&¼

é �   ¬È­&£ ��&¬ëê(­&� ¢ ¯¶¬È£ª�«­ ¨ £ Å § ¢ ��±6¯°� ¢��� � ±¶­   ©ìÇ°í ¿p¨�� ©ª»2±6� Å_¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � ¼î � � �t� ¨g  © ®� ¢ � é�ï î ê½ð�ñ¡òtðió ¿ ð�ñ¡òÆñ¡ó«¼

ô ¼ =&5ÄÌk9g?47O;LÕ�ÌÎÐ0?@5

ç � � � �&¬Æ¯ ¢ �i¯ ¢ © ��  «��&¬t§ �� ���� ¢�¨ £ª�k¬Æ»2±4¤[� � �k¬v¯ ®� ¢ � � ¤[± � § ¢ ��±6¯°� ¢��� � ±¶­   ©ìÇɬv± ¢± � ­&� ¢ ¯6¬J£���­ ¨ £ � � �õ¨�¢ ­ ¦ ©�� �� � ©ª� � �&¬   £q¤¥� ¢v �¦ �i§i� �6¨ £�©  «�� � �&¬'­ ¨g¢�¨ ­  �®� ¢ �k¬ � �k¬¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬ � ��­ ¨�¢v¢���© �¡ «��&§ ¢�¨ Â6£�� � ��­ ¨�¢�¨ ­  �®� ¢ ��­k� �2 �¢�¨ £�æ«Ê ��g¼ î £ª�iök�&£ ¨�o� �2 �¢��� µ�÷ î £ªø ¸ £q¤¥� ¢V �¦ �i§�� �_¨ £ª©  «�� � �&¬ë­ ¨�¢�¨ ­  �®� ¢ �k¬ �_¨�� ¬�£��J­ ¨ ¬ë� ®±ã£��'­&� ¢ ¯¶¬ � � ¨ ¬v�t�&¬  º� �Æ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±6£�£ª��¼ À �ÆÂ6±   ¯ ¢ © � ­k©ª¯ ¨ £ � �t­&�  �¨�¢v  ©�­&£����&¬  º� �¯ ¢ ��± Á � ¢ £Y¤[� ¢v �¦ �i§i� �_¨ £�©  «�� � �k¬Æ­ ¨g¢�¨ ­  �®� ¢ �k¬Æ¯½�i± ¢ £��'§ ¢ �i±¶¯°� ²t³�´6µY·C¸�Å »�± ¨��6�· �k¬   ± � ­k� ¢ ¯6¬t£���­ ¨ £ � ��­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � � �Ú� ±6£�£ª� µ ¬��&­   ¼¥ù ¸ ¼ î �k£ ¨ ¬�±¶ú  � � ¯ ¨�¢v  ©�­k±¶£�©�� ¢ ¯°�i± ¢ �i   � � © ¢ £��  �¦���&� ¢k®�&�o�º¬�±6© Á�¨g�2  »2±6© ��   � �¶� £�� ¢���&¬�±6£  è¨g ¹� �÷¥û ��ø ®¨ £ ¨ ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � � �ü� ±6£�£ª�Cêý Í �/2?@9«þ/2�ÿ/�� ï ��©  ã· ± � ­&� ¢ ¯6¬ã£���­ ¨ £ � �$­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶� � � ��� ±6£�£ª�Ú�  

Page 2: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

�� ± � � ¨ £ª§ ®�k ¢ � ®¨õ� © Á ©ª¬�©�� � ­k� �2 �¢�¨ £ª��¬�± ¢+· � � � ©���� � ¬�©�� � #Äà ¼��º£�� ¢ ¬.©�£��Ê«©�¬   �º± � ��± � ©�»2±6��­&� ¢�¢ �k¬v¯°� �¶�_¨�� ­&��Â6©��v�&­   © Á �È� �¡ �¢ ��£Y¤[� � ¬��&��Â6£�� � �k¬�­k£ ¨ ¬�¬v�k¬� ¤ ��k»2±6© Ág¨ £ª� � ­&� � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ¬x�k¬v¬�� �2  ©��&£�£��&�o� �¡ x� ��­ ¨�¢v¢����© �2 «��k§ ¢�¨ Â6£ª��© ¢v¢��� � ±6­   ©�Â6£ª�k¬� � ²J³�´¶µq·�¸ �   £Y¤[� � ¬��&��Â6£�� � �&¬'­k£ ¨ ¬�¬v�k¬ � ¤ ��&»2±6© Ág¨ £ª� � ­&� � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬© ¢v¢��� � ±6­   ©�Â6£ª�k¬ � � ���   �k£�£ª�H»�±¶�¹£��&¬L­ ¨�¢�¨ ­  �®� ¢ �&¬ � � � �k±«ÊJ­&£ ¨ ¬v¬��k¬ � ¤ ��k»2±6© Ág¨ £ª� � ­&�»2±6©C¬�� ­k� ¢�¢ �&¬�¯½� �6� � �¡  ¬v�i©�� �2  ��&§ ¨ ±«Ê Ũ ± ¬�©ª§ � � µ� ô ¸ ´� � ¯ ¢k®�&¬ Å ¬�± ¢Ú� �k¬��k£ ��k��� �¡  ¬�»2±6©x� �¡  £��ë����k���믽�i£ à�� ��i���ë­ ¨g¢�¨ ­  «�� ¢ ©�¬   ©�»2±6�ë¬ ��k¯ ¨g¢�¨ Â6£ª��¼

î � ¢���&¬�±6£  è¨g  �&¬   £��C¯ ¢ �k��©�� ¢ ¯ ¨ ¬ � � ¢���k­k± ¢�¢ � � ­k� �_¨�� ¬ë£ ¨.����k��� � ¬  �¢�¨g  ©ª� �� ¤¥± � �.­&� ¢�¢ �k¬�¯½� �6�6¨�� ­k� � �.¾ ¨ ­&»�±¶�  v¿áÀx¨�� §i£ ¨��6� ¬�� �¡ �¢ � ²J³�´ �   ¬v�k¬�Ç0� ¢ �o�&¬© �¡ «�� ¢ ©ª�k± ¢ �k¬:� � ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶� � � �Æ� ±6£�£ª� µbÁ �i© ¢�÷������ øi¯°�i± ¢ £ ¨ ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶�� ±6£�£ª� ¸èÅ �   »2±6©OÇ0� ¢�¨ £��'¬v±��v�  Æ� ¤[± �Ú¨�¢V  ©ª­k£��t¯ ¢ �«­ ¦_¨ © � ¼ �ë¨�� ¬�£ ¨ ¬v�k­   ©�� � óo� ��o� �2 �¢ �t»2±4¤[©ª£ àü¨� �¢�¨�� ¬VÇ0� ¢v �� �   �i±   �k¬È£��k¬º© �¡ «��&§ ¢�¨ £��k¬�� ¢ Â6©  �¨ £��&¬ � � ��� Á � ¢ ¬²J³�´¶µq·�¸ �  Æ� �   �i±   �&¬ë£��&¬ë© �¡ «��&§ ¢�¨ £ª�k¬ë� ¢ Â6©  �¨ £��&¬ � � ²t³�´6µY·C¸È� ±6£ª£��k¬ë¬v± ¢ £��&¬��k£ ��k��� �¡  ¬�¬v�k��©�¬�©ª�o¯¶£��k¬ ¢���k§�±6£�©ª� ¢ ¬ � � � �&£�£ª©�¯   ©�»2±6�k¬ Á � ¢ ¬ ��� ¼Àx¨ ¬  �¢ ±6­   ± ¢ � � �H£q¤ ¨�¢v  ©�­&£����&¬   £ ¨ ¬�±¶© Ág¨��¡  ��ê �_¨�� ¬x£ ¨ ¬v�k­   ©�� � ð � �i±¶¬OÇ ¨ ©ª¬�� � ¬»2±6�k£ª»�±¶�k¬ ¢�¨ ¯6¯°�&£�¬º¬�± ¢ £ª�k¬º§ ¢ �i±¶¯°�&¬ ¢��� � ±6­   ©ªÇ0¬�¬v± ¢ ± � ­k� ¢ ¯6¬�£���­ ¨ £�� �6¨�� ¬�£ ¨¬��&­   ©ª� ����� ��±6¬�¯ ¨ ¬�¬v� � ¬º� �ü¢ � Á ±6�J»2±6�k£ª»�±¶�k¬ ¢���k¬v±6£  �¨g  ¬ � � À �k� ¨ © ¢ �ë­k� � ­k� ¢p¿�_¨��¡  £ª�k¬�­&� ¢ ¯6¬�¯ ¢ ��­ ¦ �k¬��¡� � ±   ©�£ª©�¬ ¨g�2  ­k�&¬ ¢���k¬v±6£  �¨g  ¬ � � À �k� ¨ © ¢ � � �i±¶¬�¯ ¢ �i± ¿Á � � ¬ �_¨g� ¬º£ ¨ ¬��k­   ©ª� � ù�£�� ¢���k¬�±¶£  è¨<  ­&� �¡ �¢�¨ £ � �J­&�  º¨�¢V  ©�­&£�� Å £q¤¥� ¢v �¦ �i§i� �6¨ £�©  «��� �k¬×­ ¨�¢�¨ ­  �®� ¢ �&¬�¯°��± ¢�²t³�´ ¬�± ¢ ± � ­k� ¢ ¯6¬�£ª�«­ ¨ £ � �õ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � � �� ±6£�£ª� µ0 �¦ ¼¥ù6¼¥ù ¸ ­k� � ¬ ��k»2±6� � ­k� Å æ �_¨ £ª�k��� �¡ �Å@� ¤¥± ��¨ ±  �¢ � ¢���&¬�±6£  è¨g È �¢k®�k¬�¯ ¢ ��­ ¦ �êã£Y¤ ��&§ ¨ £ª©  «��o¬�± ¢ £q¤¥� � ¬��k�'Â6£�� � �&¬ ��k£ ��k��� �¡  ¬�&£�£�©ª¯   ©ª»2±6�k¬C¬ ��k¯ ¨�¢�¨ Â6£ª�k¬�� �¡ �¢ �㣪�­k� � �v±6§i± ��*­&�i�o¯¶£���Ê«� � ± ­ ¨g¢�¨ ­  �®� ¢ � � ¤[± � � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � �&¬�¬�� �¡  ©��&£�£ª�k��� �¡ � ��­ ¨�¢�¢����© �2 «��k§ ¢�¨ Â6£ª�º�   £q¤¥© �¡ «��k§ ¢�¨ £���� ¢ Â6©  �¨ £�� � ¤¥± �*� �º¬��k¬¹¯6¬��&± � ��­k���&ú�­k©ª� �¡  ¬µb �¦ ¼[ù¶¼ ��¸ � �_¨g� ¬x£ ¨ ¬v�k­   ©�� � ó � �i±¶¬   © ¢ � � ¬4­&�i���o��­&� � ¬ ��k»2±6� � ­k� � ��£q¤¥� ¢v �¦ �i§i� �6¨ £�©  «��£ ¨ ¯ ¢ �k± Á � � ±  �¦¹��k� ¢k®�k��� �� � � � ­ ���¯6£�±¶¬ ¦6¨ ±   � ��¢ �&� ¨g¢ »2± ¨��¡  »2±6�   �i±6¬H£ª�k¬ ¨�¢p¿§i±6��� �¡  ¬ � �J£ ¨�¹��k��� � ¬  �¢�¨<  ©�� �ü� � ÷�� £ªøx� � ­ ¨g¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±6£�£ª�ÆÇ0� � ­   ©�� �«¿� � �¡  � ¨ © �¡  � �_¨��¡  � � ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶� � � � � ±6£ª£�� µb �¦ ¼Só�¼ ô ¸ ��� � ¬v±6©   � � ��±6¬±   ©ª£�©ª¬�� � ¬'£�� ¢���&¬�±6£  è¨g �� ±  �¦ ¼Só«¼ ô ¯°�i± ¢ � �â���� � ±6© ¢ �+£��*­&� ¢ �i£ª£ ¨ © ¢ �.ó«¼Sð Å ±   ©�£��¯°��± ¢ £ ¨$�¹��k��� � ¬  �¢�¨<  ©�� �Ö� ��£ ¨ ¬�± ¢ �v�k­   © Á ©  «�� � ��£ ¨ ­k� ¢v¢ �&¬�¯½� �6�_¨�� ­k��� �¡ �¢ �²J³�´ �  t  �i±   �k¬Æ¬��&¬tÇ0� ¢ �o�&¬Æ© �¡ «�� ¢ ©��&± ¢ �&¬Æ� � ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � � �Ú� ±6£�£ª� µq¨�¢p¿  ©ª­k£���� � ¯ ¢���k¯ ¨�¢�¨g  ©�� �ÄÅ8Á �i© ¢*÷��ɨ ø Å ­ ¦_¨ ¯Ä¼ ��¸J¨ © � ¬v©�»2±4¤¥± �õ¢���&¬�±6£  è¨g �� �  �¢�¨�� ¬ ¿Ç0� ¢V '� �&¬'© �2 «��k§ ¢�¨ £��&¬J� ¢ Â6©  è¨ £ª�k¬Æ� � ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � � �ÿ� ±6£ª£�� µ ­k�  �  �oÇ0�i©ª¬J£ ¨����k��� � ¬  �¢�¨g  ©ª� �*� � ÷�� £ªø � �ëÇ0� � ­   ©ª� �6� �믶£�±6¬&¼

𫼠� �/25 �/¡9<36-0ÐdÌ �/��

Page 3: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

�ï �i©ª� �¡ (· ± � ­k� ¢ ¯6¬H£���­ ¨ £ � � ��¨�¢ ­ ¦ ©�� �� � ©�� � �  (² £���§ ¢ �i±6¯½� � �k¬ ·�¿ ¯½�i© �¡  ¬� ¤¥± � § ¢ �i±6¯½� ¨ £�§ ��& ¢ ©ª»�±¶� ¢��� � ±¶­   ©ìÇ �����æ � ©(¬�± ¢J· ¼ ���$� �   � ²�� £Y¤[� � ¬��&��Â6£ª�� �k¬ ��k£ ��&�o� �¡  ¬��&£�£�©ª¯   ©ª»2±6�k¬ ¢���&§i±6£�©ª� ¢ ¬ � � ² �  �²���� £Y¤[� � ¬��&��Â6£�� � �k¬ ��&£ ��&�o� �2  ¬¬��&�o©ª¬�©���¯6£ª�k¬ ¢���&§i±6£ª©�� ¢ ¬ � � ² ¼ ï �i©  �� £��(­k� �¡ �¢ � � � ² ¼ ï ��©�� �¡ �� ± � ���o�&¬�± ¢ �� �� ¨�¨�¢ ¬�± ¢º²Å��� ± � �Æ���k¬�± ¢ � � �� ¨i¨�¢ ¬�± ¢�� �  ���� £ ¨ �o�&¬�± ¢ �ë»�±¶�   ©ª� �¡ ¬�± ¢¹²���� ¼ ���.� �   ��� µY²C¸ £q¤¥�k¬v¯ ¨ ­&� � �&¬¹Ç0� � ­   ©�� � ¬ ����&æ � ©ª�k¬É¬v± ¢É² ®¨tÁg¨ £ª�k± ¢ ¬�_¨�� ¬�� »2±6©4¬v� �¡  £���­ ¨ £��k��� �¡  ­k� � ¬  è¨g�2  �k¬��  '®¨ ¬�±¶¯6¯°� ¢v  ­k���o¯ ¨ ­   ¼ ï ©�� �k¬  ± � ¬���±6¬ ¿ § ¢ �i±¶¯°����± Á � ¢v  ­k���o¯ ¨ ­  �� � ² � ��� �   ��� µq² � � ¸ £ª�'¬���±6¬ ¿ �k¬�¯ ¨ ­k�� �!� µq²�¸ Ç0� ¢ � �� � �ÆÇ0� � ­   ©�� � ¬�¶© ¿ © �¡Á�¨g¢ © ¨g�2  �k¬É¯ ¨�¢ � ¼ï �i©  �" £Y¤[� � ¬��&��Â6£�� � �k¬¬���±6¬ ¿ § ¢ �i±¶¯°�&¬C�i± Á � ¢v  ¬�­&�i��¯ ¨ ­   ¬ � � ² ¼ ���Ó¨� µq²�¸$#&%('*),+ � µY² �-� ¸ ¼���+¨ ¯6¯½�k£ª£��È­ ¨�¢�¨ ­  �®� ¢ � � � ² µb� � �Ƹ ± � �o� ¢ ¯ ¦ ©ª¬����º­&� �¡  © � ± � ��§ ¢ ��±6¯°�&¬� � ² µY� � �븹�6¨�� ¬�� � ¼ï �i©  !. ± � ­ ¨�¢�¨ ­  �®� ¢ � � � � ¼ ���ÿ� �   �/� µq² � .�¸ £q¤¥�k¬v¯ ¨ ­k� � �k¬JÇ0� � ­   ©�� � ¬����&æ � ©��&¬È¬v± ¢È²�®¨�Á�¨ £��k± ¢ ¬ �_¨�� ¬0�Ý»2±6© Á��� ¢ ©ªæ6� �¡  ê¿*1 �k¬   £ª�«­ ¨ £��&�o� �2  ­k� � ¬  è¨��¡  � ®¨ ¬�±¶¯6¯°� ¢v  ­k�i��¯ ¨ ­   �o� � ±6£ª� � �  ¿ ¯½�i± ¢�  �i±  2�/3�² �  �  �i±  0�435�JÅ618µ7�8�_¸$#9. � µ7��¸:1Lµ;�_¸< ��± ¢�  �i±   � 3=" � ��� �   ��� µY² � � � .�¸ £��J¬��i±¶¬ ¿ � � ¬��&��Â6£ª� � ��� µY² � .�¸Ç0� ¢ � �� � �ëÇ0� � ­   ©ª� � ¬�Â6© ¿ © �2Ág¨�¢ © ¨��¡  �k¬É¯ ¨g¢ � ¼���ר � µY² � .�¸�#>%('*)�+ � µq² � � � .�¸ ¼ï �i©  �? ± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� ��¨�� �o©ª¬�¬�©ªÂ6£�� � � ² ¼ < ��± ¢º  �i±  @1A3 � µq²�¸ � �¯°��¬�� ?HµB1x¸�#DCFE!18µ;�_¸G?Hµ;�_¸H�� ¼ �ë� ¬ ¨ ©   »�±¶� ?HµG1x¸ �k¬  �¨ £�� ¢ ¬Æ± � ��¯ �� ¢�¨g  �&± ¢� � ¢�¨�� §�æ � © Å6� � � ­ ®¨' �¢�¨ ­k�g¼ ���*� �   ��IKJ�£ ¨ Ç0� � ­   ©�� � ­ ¨�¢�¨ ­  �®� ¢ � � � ?�Å ­g¤[�&¬  ®¨×� © ¢ �w£ ¨ Ç0� � ­   ©ª� � �����æ � ©ª�.¬�± ¢�² ��� £���­ ¨ £��k��� �¡  ­k� � ¬  �¨��¡  �*�   »�±¶© ÁH�� ¢ ©ªæ_� ů°��± ¢É  �i±  0153 � µq²�¸ »�±¶©:�k¬  C®¨ ¬�±6¯¶¯°� ¢V ��_¨�� ¬ ² �;� Å

LNM ?HµB1:¸$#>O E�PRQ IKJ µ��@¸N18µ;�_¸BS�µbÁ �i© ¢w÷ ¿ î ð<ø ¸ ¼ ��� � ©   »2±6�.£ª�o­ ¨�¢�¨ ­  �®� ¢ � � � ? �k¬  UTWVYX-Z[TW\,]^\,_a`�bc_a`ed\ f8ghZSi�TW\¬�©�IjJo�k¬   £���­ ¨ £��k��� �¡  © �¡ «��&§ ¢�¨ Â6£��t¬�± ¢�² �   ¬�©L£ ¨o¢ �k£ ¨g  ©ª� � ¯6£ª±6¬ ¦6¨ ±  Æ¨ £ª©��&±¯°��± ¢È  �i±  �1k3 � µq²�¸èÅ ¬ ¨g� ¬�­k� �6� ©   ©�� � ¬�± ¢ £��J¬�±6¯6¯½� ¢V  ¼ ��� ¬ ¨ ©   »2±6��­g¤[�&¬  £��º­ ¨ ¬�¬v© · �&¬  �� ��­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � ±6£ª£�� µ�÷ ¿ î ô ø ¸ �i±*¬v© ²l# ²t³�´*µ�÷¥À �ÎðQø ¸ ¼ï �i©  �? ± � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¨�� ��©�¬�¬v©�Â6£ª� � � ² ¨�� ���  v è¨��¡  ± � ­ ¨g¢�¨ ­  �®� ¢ �­k� �2 �¢�¨ £ . µ ­�¤¥�k¬  ã  �i±��v�i± ¢ ¬+£��ß­ ¨ ¬ã¬v© ? �k¬   £ª©�¬�¬v��© ¢v¢��� � ±6­   ©�Â6£ª� ¸ ¼ ï © 1m3� µq² � .�¸_¨ £�� ¢ ¬Ä¯½�i± ¢4  �i±  j���_¨�� ¬ � �   ¯°�i± ¢Ä  �i±  K���_¨g� ¬ ² � �ƨ�18µ7�8�_¸B?Hµ7�8�_¸$#18µ;�_¸G?Hµ;�_¸ �   � � ¯°�i¬v� ?HµB1x¸(#nCoEep�q�18µ-��6¸B?Hµ-��6¸H��� ¼< ��± ¢ ± � ­ ¨g¢�¨ ­  �®� ¢ � . æ¶Ê ��o� � ¯½�k±  J�����æ � © ¢ ­&�i�o��� �_¨�� ¬ ÷ º�&ø(± � � ¨ ¯ ¿¯6£�©ª­ ¨g  ©�� �ü� �4� µY²C¸É�_¨�� ¬�� µq² � .�¸ 꺯°��± ¢º  �i±  !1r3 � µq²�¸ � � ¯½�i¬v�C¯°�i± ¢  �i±  2�/3�² ê 1Ys°µ;�_¸$#>O q .ºµG��¸N18µG�o�@¸B��ut

Page 4: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� < ��± ¢�  �i±  �  � ¢ ��� ¨ Ê«©�� ¨ £�� � � ² � � æ¶Ê«�C± � �C���k¬�± ¢ � � �4 ¨i¨�¢0 L ¬v± ¢�t¼ �ë� ¬v±6¯6¯½�i¬�� �_¨g� ¬   ��±   ��£ ¨ ¬�±¶©   �'»�±¶�C£�� �v�&± � �k¬ë���k¬v± ¢ �&¬ ¨ © � ¬v©Læ¶Ê ��&�k¬¬�± ¢ £ª�k¬   � ¢ �k¬�� ¨ Ê«©�� ¨ ±«Ê � � ² ÁH�� ¢ ©ìæ_�ê¿ ¬�©�� �   ���x¬v� �¡ t� �k±«Ê   � ¢ �k¬ë� ¨ Ê«©�� ¨ ±«Ê � � ² ­&� � �v±6§i± ��k¬ �_¨�� ¬ ²Å £��&¬�o�&¬�± ¢ �k¬ L �   L �¡æ«Ê ��&�k¬(¬�± ¢ �â�   ��� ¢ �k¬v¯°�&­   © Á �&�o� �¡  ¬v�È­&� ¢�¢ �k¬v¯°� �¶� � �¡ (Á © ¨­k�  �  �Æ­&� � �v±6§ ¨ ©�¬�� �$µ ­k�&£ ¨C� � ����k¯½� �¶� ¯ ¨ ¬ � ±ü­ ¦ �i©�Ê ¸ �  ¿ ¬�©�� �k¬   ± �ü  � ¢ �ë� ¨ Ê«©�� ¨ £½�k£�£ª©�¯   ©�»2±6� � � ²Å_¨ £ª� ¢ ¬ L �k¬   £ ¨ �o�&¬�± ¢ � � � ¨i¨g¢ ¬�± ¢ �   �k£�£ª��»2±6��� � � ¨ ©  �Á �i£ª±6�o� ��&§ ¨ £ ®¨ ô ¯°�i± ¢ £ ¨ �o�&¬�± ¢ �Æ»�±¶�   ©ª� �¡  �L #n L �8�� ¼< ¨g¢ £ ¨ ¬�±6©   � Å ¬v© 153 � µq²�¸ ��± 1 3 � µY² � .�¸ ¯°�i± ¢ ± � ­&� ¢v �¨ © � ­ ¨g¢�¨ ­  �®� ¢ �.ß� � �JÅ ¬�© �03�² �;� Å ¬v©�� µb  � ¢ ��� ¨ ʶ©ª� ¨ £ ¸ �&¬   £ª��­&�i�o�'±  è¨��¡ L� � ���_¨�� ¬ ²Å� �×� �   � � µB1 � �&¸ # CFEep�� 18µ-�� � �8��_¸H��� £q¤¥© �¡ «��k§ ¢�¨ £��Æ� ¢ Â6©  �¨ £�� � � 1ÿ¨ ±ã¯°�i© �¡ � ¯½�i± ¢ £ª�ë­ ¦ �i©ìÊ � �Æ�o�&¬�± ¢ �k¬È¯6£�±¶¬ ¦6¨ ±   ¼À � ¢���&¬�±6£  è¨g  ¬v±6© Ág¨��¡  �k¬   ¬��i± Á � �¡  ¬��i±¶¬ ¿ � �¡  � �¶� ± �_¨g� ¬x£ ¨ £ª©  � «�� ¢�¨g  ± ¢ ��¼��º��±6¬� � �6� � � ¬�£ ¨�����&�o� � ¬  �¢�¨g  ©�� � ¯½�i± ¢ £ ¨ ­&�i���o� � ©  «�� � ±ü£��&­   �&± ¢ ¼� 9<?_ØH?½�kÐdÌÎÐ0?@5�� ����� � Z������e\�T�����\ ��V8b�`�1 3 � µY²C¸"!21 sr3 � µY² � .�¸$#&%*_V�i�`;b7\,_a` Z bc_'� b(��_ \ Z*)+)6T b7X-Z[`�b7V8_-, s êS� µq²�¸/. � µq² � .�¸$#i"�0, s \$� `1�2��g�3,\ X�`�b548\6#X"�7)uV� g!`GV�u` 153 � µY²C¸�\�`�)uV��g�`GV� `B\�g \8)ag d\$��\,_a`7Z[`�b7V8_5Z+9 ]�b:�;� b7i�TW\�?<9S\²=9S\�X-Z g ZSX�`+>\,g \�X \,_a`�g Z[Tu.?! V8_ Z�?HµB1:¸$# ?HµB1 s_¸$#9��@)uV��g�`GV� `(1 3 � µY²C¸"!�)uV� g!`GV�u`�/3�² ! V8_ Z-A

� µG1Ys � �_¸$# O q .ºµG��¸ � µB1 � �8�_¸H��utD �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �Ó¨�¸Æ�ë� ¨ � µq²�¸�# %('*),+ � µY² � � ¸ ¼ < �i± ¢ � 3n"� �   � � ¬ ¨ Â6±¶¬�© Á �k��� �¡  �CB ²�� � ± � � � ¬��&��Â6£ª� � � ¢ �k¯ ¢���k¬v� �¡ è¨g�2  ¬ � �&¬�­k£ ¨ ¬�¬v�k¬� ¤ ��k»2±6© Ág¨ £ª� � ­&� �6¨�� ¬^�CB ²�� � ¼ ��£ª� ¢ ¬ Å ¯½�i± ¢ ­ ¦_¨ »2±6� � 3 " £Y¤[� � ¬��&��Â6£ª�D ��'/Eh'GFF'�H Eep ' �k¬   ± � � ¨ ¬v� � ± � ¿ �k¬�¯ ¨ ­k� Á �k­   � ¢ ©ª�k£ � µY² �-� ¸ ¼ ï �i©  @�I 3�CB ²�� � ¼Hç � ­ ¨ £ª­k±6£4¬ ¨�� ¬ � ©ªú�­&±6£  «��ë�o� �¡ �¢ �ë»2±4¤¥� �ר ê, sĵ"�S'/EKJ7'ȸ(L ñ¬�© �NM � � � � �PORQ M µ�.�¸�  , s°µ8��'/ESJG'º¸èµ;�_¸$#UT ñ¬�© � �35� � � �. � µ7�Vk¸SW QYX µB�NM � � � � � ¸ ¯½�i± ¢�� 3 � � �I �[Z ��#n�V O �:� O ì�© �NM � � � � � \<ORQ M µc.�¸ ¼���üÁ �i©   »2±6� , s4µ8�S'/E J 'º¸HÁ��� ¢ ©ªæ6��ê¿ XV] íií µ^, s°µ"�S'/EKJ7'º¸�¸ \ � � � �¿_, sĵ8��'/E J 'ȸ �&¬   Â6© ¿ © �¡Ág¨�¢ © ¨��¡  �º¯ ¨�¢ �¿_, sĵ8��'/E J 'ȸèµG�8�_¸(# . � µG��¸S, sĵ"�S'/E J '�¸Òµ��@¸(`��435� Z `6� 3�² ¼

Page 5: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

���© � ¬�© , s°µ"�S'/E J '�¸ 3 � µq² � � � .�¸ �   £��믽�i© �2 tµY¨�¸ �k¬  È�¹��k��� �¡ �¢����¼Â ¸ é � �2 �¢ � � ¬�£ ¨ ¬�± ¢ �v�k­   © Á ©  «�� � � , s ¼ ï �i©  ��n3 � µY² � .�¸ ¼��á£É��Ê«©�¬   � �¬��i±¶¬ ¿ § ¢ �i±6¯½���i± Á � ¢v  �   ­k�i��¯ ¨ ­  '� � ²   �&£H»�±¶� � 3 � µY² �-� � .�¸ ¼ ���$Ág¨�o� �2 �¢ � ¢ »2±4¤¥©�£8�ÒÊ«©�¬   � 1r3 � µq² � � ¸�  �&£8»2±6� , s°µB1x¸2#�� ¼ ï ©�� 3 XV] í�í µ��°¸èÅ� �ü¨ ¯ ¨�¢ £��ë����k���ë­ ¨ £ª­k±6£Ä©���� �� � © ¨g  »2±6�Ư6£�±6¬ ¦_¨ ±  �NM ����� � \<ORQ M µc.�¸ té ¨ © �¡  � �6¨��¡  D ���� F�[) '�H Eep ' �k¬   ± � �w¯ ¨�¢V  ©   ©�� ��� � ²Å �  �� ��  è¨��¡  Â6© ¿© �¡Ág¨�¢ © ¨��¡  �o¯ ¨�¢ � Å ©�£(��Ê«©ª¬   � � �k¬��� 3 ² Z�� 3���Å�  �k£�¬'»�±¶� D ��� � F )��¬��i©   ± � ��¯ ¨�¢V  ©   ©�� �ã� � XV] íií µ��°¸ �   »2±6� � ¬��i©   ­&� � ¬  �¨��¡  ��  ×��k§ ¨ £ª� ®¨��:µ �� ¸¬�± ¢ ��� � ¯°�i± ¢Æ  �i±   � 3�� ¼ � �¯6£�±6¬ Å ¬v©H� � ­&� �6�_¨ � �  �� ¬�± ¢ ��� ,� Å � �£ ¨ ­&� �6�_¨ � �   ¬�± ¢�� ��� ,� ¯°��± ¢ë  �i±  !�53 � êÆ­�¤¥�k¬  !. � µG��¸��xµ �� ¸ ¼ î �i�����XV] í�í µ��°¸ �k¬   ­k�i��¯ ¨ ­   ��� � ±6£�� � � � ¯°�&±  � �¢ �i± Á � ¢ ± � ¬v�i±6¬ ¿ � � ¬v�k��¶£��'æ � ©� � � � ��  �&£:»2±6�oê

�:µ;�_¸$# T . � µ7��¸��:µ �� ¸ ¬�© �/3 � � �� ,� ¯½�i± ¢ ± � �435� �   ± � � 3�� �ñC¬�© �A�35% )���� � ! ) q � � �� ,� t

î �i���o��� �ÿ¨üÁ ± »2±6� ÷ �� 3 XV] íií µ"�ĸ ø$# ÷ ��M ��� �� � \ ORQ M µ�.�¸ ø Å� ¤ ¨ ¯ ¢k®�&¬�£��ë­ ¨ £�­k±¶£ � � , s°µ"�S'/E J 'º¸ »2±4¤¥� �ר Ç ¨ ©  �¨ ± ����k¶±  �Å ¬�©:� � ¯½�i¬v��/#&% )�� � �:µ �� ¸�÷ W QYX µB� M ��� ,�� � ¸ ø � �S'')(h' Z¨ £�� ¢ ¬É� �㨠Â6©�� � , sĵB1x¸$#�� ¼­ ¸É���㨠ê?HµG1Ys@¸$# O Eep�q 1Ys°µ-��_¸B?Hµ-��6¸H����# O Eep;q�* O q .ºµ7��¸:1LµG�6��_¸H���+6?Hµ-��6¸H���4## O Eep�q O q .ºµ7��¸:1LµG�6��_¸B?�µ ��6¸H�� ���# O Eep�q O q 18µ7�6��_¸B?Hµ7�6��_¸H�� ���4#

#>O E 18µ;�_¸G?Hµ;�_¸H���#9?�µB1x¸-t�°¸ î ¨ £�­&±6£�� � ¬È¯½�i± ¢��I@3 ² �;� µ � ����&¬�©ª§ � �'©ª­k©x£��t­k���o��±  è¨��¡ È� � ���_¨g� ¬²C¸ ê

� µ;� � 1Ys@¸$# O Eep�� 1Ys°µ-�� � �Io��6¸H���4# O Eep��,* O q .ºµG��¸N18µG�a�� � �Io��6¸B ��+���� ##>O q .ºµ7��¸ * O Eep�� 18µ7�6�� � �o��6¸H��� + ���#>O q .ºµG��¸ � µG�8� � 1x¸B � t

Page 6: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

ï �i©ª� �¡ ��wµq²�¸ £Y¤[� � ¬��&��Â6£ª� � �J­k£ ¨ ¬�¬v�k¬ � ¤ ��&»�±¶© Ág¨ £�� � ­k� � �k¬ ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬£�©ª¬�¬��&¬L© ¢�¢��� � ±6­   ©ªÂ6£��&¬ � � ² �  �Å ¯°��± ¢L  �i±   ­ ¨�¢�¨ ­  �®� ¢ � .ß� � �JÅ��oµq² � .�¸ £��(¬��i±6¬ ¿� � ¬v�k��¶£�� � � �oµq²�¸ Ç0� ¢ � �� � �C­k£ ¨ ¬�¬v�k¬ � ¤ ��k»2±6© Á�¨ £�� � ­k� � �C­ ¨�¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £. ¼ ���Ó� �   ��� µY²C¸ £Y¤[� � ¬��&��Â6£ª� � �k¬C­ ¨�¢�¨ ­  �®� ¢ �&¬ � � �õ¢�¨ ��©ªæ ��k¬ � � ² ��± � ©� �*¬ ¨ ¬  �¢ ±¶­   ± ¢ �+±6¬�±¶�k£�£ª� � � Ág¨�¢ © ��  «�� ¨ £ª§ ��k ¢ ©�»2±6�g¼ ï © ? 3��oµq²�¸èÅ � �õ� �   �� µq² � ?8¸ £ª�.¬��i±¶¬ ¿ � � ¬��&��Â6£ª� � � �wµq²�¸ Ç0� ¢ � �� � �*­k£ ¨ ¬�¬v�k¬ � ¤ ��k»2±6© Ág¨ £ª� � ­&� � ± áà ¯°� I�� ? � ®±5I 3 � µq²�¸èÅ ��± � © � �o¬ ¨ ¬  �¢ ±6­   ± ¢ � � � Ág¨�¢ © ��  «�� ¨ £�§ ��& ¢ ©ª»�±¶�©�¬v�i�o� ¢ ¯ ¦ � ®¨ ± � »2±6�   ©ª� �¡ C� �� µY²C¸ ¼ ���õ� �   � � à µY²C¸ £ª�w¬v�i±6¬ ¿ � � ¬v�k��¶£��� � �oµq²�¸ Ç0� ¢ � �� � ��­k£ ¨ ¬�¬v�k¬ � ¤ ��k»2±6© Á�¨ £�� � ­k� � �&¬ ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � ¬��k¬v¬�� �¡  ©��k£ª£�� ¿�o� �¡ L� ��­ ¨�¢�¢���(© �¡ «��k§ ¢�¨ Â6£ª���   ¯°��± ¢:  �i±   ­ ¨�¢�¨ ­  �®� ¢ � .�� � � � �'� �   � � à µY² � .�¸£q¤¥� � ¬v�k��¶£�� �oµq² � .�¸6M� à µY²C¸ ¼ � �É����k��� Å � �C� �   � ���VµY²C¸ £ª�¹¬v�i±6¬ ¿ � � ¬v�k��¶£��� � �oµq²�¸ Ç0� ¢ � �� � ��­k£ ¨ ¬�¬v�k¬ � ¤ ��k»2±6© Á�¨ £�� � ­k� � �&¬ ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � ¬��k¬v¬�� �¡  ©��k£ª£�� ¿�o� �¡ 4  �&�o¯ �� ¢���&�k¬x�   ¯½�i± ¢4  �i±   ­ ¨�¢�¨ ­  �®� ¢ � .ã� � � � �ë� �   � � � µq² � .�¸ £q¤¥� � ¬v�k��Â6£ª��wµY² � .�¸ M � � µY²C¸ ¼� ©�ʶ� � ¬J± � ­ ¨g¢�¨ ­  �®� ¢ � .Ý� � � ¼ ï �i©  �?n3�� à µY² � .�¸ ¼ ���ÿ� ©   »2±6� 1 J 3� µq² � .�¸ �k¬   ± � ) ��\*�'9SVYX VY\�� X,b7\,_a`(� � ? ¬v© LNM ?HµB1 J ¸�# ô �   LNM�� µG1 J ¸�# ñ¯°��± ¢É  �i±   � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � � 3�� � µq² � .�¸ B D ?/F ¼ý Í �/2?@9«þ/2�ÿ/ � � � � ��� V8b�`? 3�� à µq² � .�¸$#Z����@TWV8g;�2? )uV �;��>\V9S\���_ ) ��\*�R9SVYX VY\�� X,b7\,_a`1 J #i"���2V��g `GV� ` ��V�����;f8g V�Y)u\ ) Z ghZSi V T b�����\ )ag V$)ag \�� 9S\*² ! � b�³ \$� ` � _��V�����;f8g V�Y)u\ 9S\���\*4Yb(9S\�� !�� b! 5\$� `1��_ \!g \8)ag d\$��\,_a`7Z[`;b7V8_ T b:�;��\!bcg g d\V9I�eX�`�b7i�TW\9S\t³ `B\�TcTW\ ���e\�T Z g \$� `�g b7X�`;b7V8_ 9I�AX-Z ghZSX�`+>\,g \4X \,_a`;ghZ[T�9S\� U>Z �m\$� `�.?!2V8_kZLNM µ#" # E$ ¶¸ÒµB1 J ¸(# ñ #X"����% bc_a`ed\ f8ghZ[TW\�V8g i,b�`7Z[TW\ �2� gɲ ��� 9&% � _ ) ��\*�'9SVYX VY\�� X,b7\,_a`�9S\2?r_ \790d\8)u\,_ 9���e\ 9S\0? #(' TcTW\ \$� ` _ � TcTW\0�2��g�² �;� B ²��6#D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 ��) ±6©  �  � ®¨+  � ¢v�6¢ ��¯ ¨�¢ ± � ­ ¨�¢�¨ ­  �®� ¢ � � � ²�Å � � ¯°�&±  ¬�±6¯¶¯°�i¬v� ¢ »2±6� . �&¬   ± � ©  è¨ © ¢ ��¼ �ë�ü����&�o� �¡ �¢ �Æ£��  �¦¹��k� ¢k®�k��� �_¨�� ¬�­&�J­ ¨ ¬Æê¨�¸ ï �i©  &* £q¤¥� � ¬v�k��¶£��Hæ � © � �k¬L­ ¨�¢�¨ ­  �®� ¢ �&¬(I 3 � µY²C¸°  �&£�¬L»�±¶�¹£��(­ ¨g¢�¨ ­  �®� ¢ �­k� �2 �¢�¨ £ � �*I+� ? ¬���©  �. µ ­�¤¥�k¬   £q¤¥� � ¬��k�'Â6£�� � �k¬�­ ¨�¢�¨ ­  �®� ¢ �k¬ � � ��¢�¨ �o©ìæ ��k¬�I � �² � � �¡  £ ¨�¢ �k¬  �¢ ©ª­   ©�� � ®¨/� �&¬  º �¢ © Á © ¨ £ª� ¸ ¼ ï �i©  �� ± � �JÇ0� � ­   ©ª� �ר £�§ ��& ¢ ©ª»�±¶�����&æ � ©��ɬv± ¢ � µq² � ?8¸É®¨�Ág¨ £ª�k± ¢ ¬ �_¨�� ¬ �   �&£�£ª�¹»2±6� �oµ�?8¸$# ô �  ,�oµ I(� ?8¸(# ñ¬�©6I 3�*JÅ I-� ?/.#9? ¼ � ©�ʶ� � ¬¹± � ��¯ ¨ © ¢ �ȯ ¨�¢�¨ °�i£ª©�»2±6����© � ©ª� ¨ £ª� � � ² ¼ ���¬ ¨ ©   »2±6�¹£q¤¥� � ¬v�k��Â6£ª� � �&¬8­&£ ¨ ¬v¬��k¬ � ¤ ��&»2±6© Ág¨ £ª� � ­&� � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬ � � ²B� ± áà ¯°� " # E$ µ10 � � ¸ � ®± � �&¬   ± � ¬���±6¬ ¿ § ¢ �i±¶¯°�ë¯ ¨g¢�¨ ½�i£�©ª»2±6��¬  �¨��6�_¨g¢��+� � ²Å� �k¬   ± � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� �ü  �k��¯ �� ¢���k�Æ© ¢�¢��� � ±6­   ©�¶£�� � ±ü¬��i±¶¬ ¿ § ¢ �i±6¯½� � � À � Á ©¬  �¨��6�_¨�¢v�.³ � � � �  +0 �&¬   ± � ­ ¨g¢�¨ ­  �®� ¢ ��¬  �¢ ©ª­   �k��� �¡  ¯½�i¬v©   ©ìÇ µb¢ �&£ ¨g  © Á �&�o� �¡ ®¨2��¸�� � ³ Ç0� ¢ �o�J± � �� ¨ ¬��C¬�± ¢3�� ±�§ ¢ �i±¶¯°� � ��ò ¢ �  �¦ � �6� ©ª�k­54 ² M76YL µq²�¸� � ² µbÁ �i© ¢C÷������ ø �'¼¥ù6¼¥Ç Å ¯½�i± ¢ £ ¨.�¹��&æ � ©   ©ª� ��� ¤¥± � ­ ¨�¢�¨ ­  �®� ¢ �¬  �¢ ©ª­   �k��� �¡ ¯°��¬�©   ©ªÇ@�   ¯½�i± ¢ £ ¨Æ����k��� � ¬  �¢�¨g  ©�� �C� �º­&� ¢���k¬v±6£  �¨g &¸ ¼ ��� £Y¤ ¨ ¯6¯°�&£�£ª�É©�­&©6£ ¨ i-Z��\9S\8��Z _ f T Z _ 9�ë� � ² M76FL µY²C¸ ¼ ���õ¨ ¯6¯½�k£ª£��C£ª�k¬ ��&£ ��&�o� �2  ¬ � �o­&�  �  �w ¨ ¬�� � �k¬g \8)ag d\$��\,_a`7Z[`;b7V8_'� � `7Z _ 9�Z g 9�� � ² �   � �C� ©   »2±4¤¥± � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � ¬  �¨��6�_¨g¢��

Page 7: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

" # E$ µ10 � � ¸ �k¬   bc_ 9I��b�`G\[� `�g b7X�`B\ ¬�© � �k¬   ± � ¬��i±6¬ ¿ § ¢ �i±6¯½��¯ ¨�¢�¨ °��£�©�»2±6�¯ ¢ ��¯ ¢ � � � ² ¼ï �i©   � ê ² M 6YL µq²�¸(. ��£q¤ ¨ ¯6¯6£ª©�­ ¨<  ©�� � £�© �¹�� ¨ © ¢ � �¹��&æ � ©��Ư ¨�¢ ê¿$�:µ��L¸(# ��µ��O¸ ¬�© � 3 � µq² � ?8¸ �  ¿ �xµ��L¸!# ñü¬�© � �&¬   ± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � � �o£ ¨  ¨ ¬v� � � ÀO¨g� §i£ ¨g�6� ¬ � �² M76YL µq²�¸ »�±¶© � �Ƭ��  �¢ �i± Á �t¯ ¨ ¬ �_¨g� ¬ � µY² � ?8¸ ¼���ÚÁ��� ¢ ©ªæ6�o»2±6� � �k¬   ± � �o½� �6� �CÇ0� � ­   ©ª� �$¨ ±$¬v� � ¬ � � ÷�� ��� ø ô ¼S𫼠À �­k£ª�i± � �Æ£ ¨�����&�o� � ¬  �¢�¨g  ©ª� � �k¬   £ª�ë£��&�o����¬�±¶© Ág¨��¡  êF(/2�$�ÿ/C� ��� � �(� V8b�`:µ�* � ��¸�� _ \/) Z bcg \() Z ghZSi V T b�����\ � `7Z _ 9�Z g"909S\H² \�` � #³�� T Z 9�d\YX V8]@)uV � b�`�b7V8_-9S\���\*4Yb � `GZ _ 9�Z g"9 9S\(� #(� V8b�` � 3�� � µq³¹¸$# d'�X,g b548V8_'�� # 0 � � V >� 0 \$� `���_ X-Z ghZSX�`+>\,g \/g d\Y\�T_9S\o³ \�` � ��_ \ g \8)ag d\$��\,_a`GZ[`�b7V8_`B\,]@) d\,g d\Y\!bcg g d\V9I��X�`�b7i�TW\ 9S\Ƴ�#��@TWV8g;��T % bc] ZFf�\ 9S\�" # E$ � 9�Z _'��² M76FL µY²C¸!\$� `A� b � ��_ \-��V8]�]^\ 9S\ g \8)ag d\$��\,_a`GZ[`�b7V8_'� \$�;��\,_a`�b7\�TcTW\,]^\,_a`�`B\,]@) d\,g d\Y\$� 9S\o²� % b�Tj\8b:� `G\0� _AX-Z ghZSX�`+>\,g-\��=9S\º²m`G\�T ���e\ M QYX E �&# 0 \�`� bcb � ��_ \���V8]�]^\ 9S\�g \8)ag d\$��\,_a`7Z[`�b7V8_'� � `7Z _ 9�Z g 9 bc_ 9I� b�`G\$�7� `;g b7X�`G\$�@� bc_ V8_ #D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 � î ��£��&�o���8¬v� ¢��� � ±¶©  x¨ ±ëÇ ¨ ©   ¬v±6© Ág¨��¡ �Å Ç ¨ ­&©�£ª� ®¨�����k��� �¡ �¢ � ¢êâ¬v©t£ª�$­ ¨�¢�¨ ­  �®� ¢ � µY¢���k�k£ ¸�0 � ¤¥�k¬   ¯ ¨ ¬  �¢ © Á © ¨ £ Å�¨ £�� ¢ ¬ü©ª£ë��Ê«©�¬   �$± �� �¢ ©�¯¶£��  µq³ � � 0 � � �@¸Æ  �k£�»2±6� ³ � .# ²�Ź³ \ ³ � Å 0 ���k¬   ± � ­ ¨�¢�¨ ­  �®� ¢ � � � ³ �   �k£�»2±6�M QYX � 0 � # 0«Å *@½µ��@¸á³ �:�k¬   ¬  è¨��¶�_¨�¢�� �  �*0½µ;�_¸ 0 �x�k¬   ± � ­ ¨�¢�¨ ­  �®� ¢ �¬  �¢ ©�­   � ¿�o� �¡  ¯½�i¬v©   ©ìÇ � � *0°µ��_¸p³ � µb¢ �&£ ¨g  © Á �&�o� �¡ 8¨ ±J¬v�i±6¬ ¿ § ¢ ��±6¯°�(¯ ¨�¢�¨ ½�i£�©ª»�±¶��¬  è¨g�«¿�_¨�¢v�ü� � ² ¨ ¬�¬���­k© �� ®¨8*0½µ;�_¸p³ � ¸ ¼î �H£��&�o���8©ª�o¯6£ª©�»2±6�O»2±6� � �  �¢ ��Ç0� � ­   ©�� � � ¬k¤ ¨��6� ±6£ª��¬�± ¢4  �i±   � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� �� � ² »2±6©6�k¬   © �¶� ±6©   � ®¨ ¯ ¨�¢v  © ¢O� ¤[± � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � £�©ª¬�¬���© ¢v¢��� � ±6­   ©�Â6£ª� � ¤¥± �¬��i±¶¬ ¿ § ¢ �i±6¯½��¯ ¨g¢�¨ ½�i£�©ª»2±6�º¯ ¢ �i¯ ¢ � µ ¯ ¨g¢ ­k��»�±¶� Å ¬�© ³ �&¬   ± � ¬v�i±6¬ ¿ § ¢ ��±6¯°� � �À � Á © � � ²�Å £q¤¥� � ¬v�k��¶£�� � �k¬�© �6� ±6©   �&¬ � �&¬ ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬��&¬�¬�� �¡  ©��&£�£ª�k��� �¡   �&�o¯ �� ¢���&�k¬ � �   �i±6¬'£��k¬J¬��i±¶¬ ¿ § ¢ �i±6¯½�k¬ � � À � Á © � � ³å®¨�³ �&¬   ± � �wÇ ¨ ��©�£ª£��§ �� ���� ¢�¨< �¢ ©ª­k� �_¨�� ¬ ² M76YL µq³¹¸�¸ ¼ < �i± ¢�ÁH�� ¢ ©ìæ_� ¢w¨ £�� ¢ ¬o»2±6� � �k¬   ± � �ã°� �¶� �Ç0� � ­   ©�� �4Å ©ª£ë¬�±¶ú  ã� � Á��� ¢ ©ªæ6� ¢ »�±¶� � �k¬  �¨ £�§ ��& ¢ ©ª»�±¶�Ú¬v± ¢ � µY² � �L¸ ¯°�i± ¢  �i±   � � 3 �oµq²�¸ ¼�� �>����&­k�i��¯°��¬ ¨��¡ �� ¬v± ¢ £ ¨  ¨ ¬�� � � Àx¨�� §i£ ¨��6� ¬ Å � �Á �i©   »2±4¤¥©�£O¬�±«ú  �� ��£ª�J¯ ¢ �i± Á � ¢��_¨g� ¬�£ª�'­ ¨ ¬�� ®± �k3 � � µY²C¸ ¼ ��¢kÅ ¯½�i± ¢ ± � �  �&£�£�� ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� ���8Ž  �i±  ü��k£ ��&�o� �¡ �� � � µq² � �L¸ �k¬  ���k£ ��k��� �¡ �� �J£ ¨  ¨ ¬v�� � ÀO¨g� §i£ ¨g�6� ¬ � � � ­ Å ¯ ¨�¢ ­k� � ¬  �¢ ±6­   ©�� �4Å�� �&¬  C¨ £�§ ��& ¢ ©ª»�±¶�o¬v± ¢ � µY² � �O¸ ¬v©�53 � µq² � ?8¸ �  �� ±6£�£ª�ɬ�± ¢ � µY² � �O¸ ¬�© � � � ¼ � � � ­ � �k¬   ± � ��½� �6� �¹Ç0� � ­   ©�� � ¼���Ó¨ ¯6¯6£ª©�»2±6�*£��  �¦���&� ¢k®�&�o� � � < ¨ £�� à2¿qÞ ©�� � � ¢+µ�÷������ ø ô ¼Sð ¸ ê.¬��i©   1 3� µq²�¸Æ  �&£�£ª�ü»2±6�ü¯½�i± ¢C  �i±  �� 3 �wµY²C¸ � � ¨ ©   LNM ��µB1:¸^# �:µ��L¸ ¼ < �i¬v� � ¬1 J # , s°µB1x¸=3 � µq² � .�¸ ¼ ÀO¨ Ç0� � ­   ©�� �>1 J ¨ © � ¬v© ����&æ � ©ª� Á��� ¢ ©ªæ6�$­&£ ¨ © ¢ � ¿�o� �¡  £��&¬×­&� �6� ©   ©�� � ¬ Á �i±6£�±¶�k¬ Å ¯6±6©ª¬�»2±6� ¯½�i± ¢ü  �i±  �� 3 �oµq² � .�¸ � � ¨LNM ��µB1 J ¸$# LNM ��µB1:¸ ¼

Page 8: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

 ¸'À �+¯6¬��&± � ��­k���&ú�­k©ª� �¡ U1 J � � ? ­k� � ¬  �¢ ±6©  �¨ ±Ó¯½�i© �¡ ¨�¸tÁ��� ¢ ©ªæ_�*­&�  v  �¯ ¢ ��¯ ¢ © ��  «��w¯6±6©�¬v»2±6�*¯°��± ¢'  ��±   � � 3 �oµq² � .�¸ � � ¨ LNM ��µG1 J ¸�# LNM ��µB1x¸ �  »2±6� 1ݨ��6� ±6£ª��£ ¨ÿ �¢�¨ ­&� � �   ��±   � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � © �¶� ±6©   � ®¨ ¯ ¨�¢V  © ¢w� ¤¥± �¬��i±¶¬ ¿ § ¢ �i±6¯½��¯ ¨�¢�¨ ½�i£�©ª»�±¶�ɯ ¢ ��¯ ¢ �g¼��á£6¬�±¶ú  �� � � ­ � �È��� �¡ �¢ � ¢ »2±6� Å ¬v© 1 �J �k¬  ± ��¨ ±  �¢ �J¯6¬v�k± � �«­&�«��úo­&©�� �2 �� � ?�ÅĨ £ª� ¢ ¬ LNM ��µB1 J � 1 �J ¸ # ño¯½�i± ¢�  �i±  ��=3�wµY² � .�¸ ¼ ï �i©  ��k3 �wµY² � .�¸ � �¹��k­&�i�o¯½�i¬v� � ¬ � ¬�± ¢ £ ¨  ¨ ¬�� � � Àx¨�� §�£ ¨��6� ¬� � ² M76YL µq²�¸ ê

� # ´%��� �

� � ? � t< ��± ¢ ­ ¦_¨ »�±¶� ? � ©ª£¡��Ê«©�¬   �(± � ¬v�i±6¬ ¿ § ¢ ��±6¯°�(¯ ¨�¢�¨ ½�i£�©ª»�±¶�(¬  è¨��¶�_¨�¢��-� � � � ²�   ± � � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � © ¢�¢��� � ±6­   ©ªÂ6£��º�k¬�¬v� �¡  ©ª�k£ª£��k��� �¡ �  �k��¯ �� ¢���k� � � � ±+¬��i±6¬ ¿§ ¢ ��±6¯°� � � À � Á ©L¬  è¨��6�6¨�¢���³ � � � � �   �k£�£ª�J»2±6� ?A#�" # E$�� � � ¼ �ë�㢠�&� ¨�¢ »2±6�»2±6�º¯½�i± ¢H  ��±  ,"�ÅS? � ¨�� �o�   ± � ­ ¨g¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £ Å2¢ �&¬  �¢ ©�­   ©ª� �o� ±w­ ¨g¢�¨ ­  �®� ¢ �­k� �2 �¢�¨ £ � � � � ®¨0� ¼ < ¨�¢ © �6����k¯½� �¶�_¨�� ­&��£ª© ���� ¨ © ¢ � � �k¬ � ©ª¬  �¢ ©�Â6±   ©�� � ¬:­ ¨�¢�¨ ­  �®� ¢ �k¬� � �¢ ��± Á � ¨ £�� ¢ ¬�»2±6�ȯ°�i± ¢H  �i±  ,"�Å £ ¨Æ¢ �k¬  �¢ ©ª­   ©�� ��� ±�­ ¨�¢�¨ ­  �®� ¢ �È­k� �¡ �¢�¨ £ � � � �®¨ � �k¬  2. ¼��º£�� ¢ ¬ LNM µ�" # E$�� � � ¸ÒµG1 J � 1 �J ¸ # ñC¯ ¨�¢ £���Ç ¨ ©   »�±¶�J£ª�k¬�­ ¨�¢�¨ ­  �®� ¢ �k¬�_¨�� ¬ � µq³ � ¸�� _eb�`7Z bcg \$� �  �� � �¡  £ ¨ë¢ �&¬  �¢ ©�­   ©�� �×®¨�� �&¬   . Ç0� ¢ ��� �¡  ± � � � ¬v�k� ¿Â6£���� ¨�¢ ©�¬ 4�© � � � ¬v� �_¨g� ¬'£ ¨ ¬v�i±6¬ ¿XÁg¨�¢ © ��  «�� � �2� µq³ � ¸ Ç0� ¢ � ��&� � �k¬t­ ¨�¢�¨ ­  �®� ¢ �k¬�_¨�� ¬ � µq³ � ¸¹� � �¡  £ ¨C¢ �&¬  �¢ ©�­   ©�� �ÿ®¨ � �k¬  2. ¼­ ¸É���ü¨ �o� �¡ �¢���ë»2±6� � �k±«Ê*¯6¬��&± � ��­k���&ú�­k©ª� �¡  ¬ � � ? � �2  £ ¨ ����&�o�  �¢�¨ ­&�¬�± ¢ £ª�k¬ ��k£ ��k��� �¡  ¬ � � �wµY² � .�¸ ¼ < ¨�¢¹÷������ ø Åk �¦ ¼��'¼l𫼠¨«Å<Ág¨�¢ © ¨��¡  ��ð µbÁg¨ £ ¨ Â6£��8� �  �i±   ��­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶� ¸èÅ ©�£�¬(� �¡  £ ¨ ����&�o�º© �¡ «��&§ ¢�¨ £ª��� ¢ Â6©  �¨ £��º¬�± ¢É² ��� ¼ < ��± ¢�o� �2 �¢ � ¢ »2±6�ü£q¤¥© �¡ «��k§ ¢�¨ £��.� ¢ Â6©  è¨ £ª� � ¤[± � ¯6¬v�k± � ��­k���&ú�­&©�� �¡ w� � ? ¬k¤ ¨��6� ±6£ª�¬�± ¢(² �;� B ²�� ©ª£6¬�±¶ú  �� � � ­ � �È£������ �¡ �¢ � ¢ ¯°��± ¢ ± � ¯6¬v�k± � �«­&�«��úo­&©�� �2  ¯ ¨�¢V  © ¿­k±6£ª©�� ¢ ¼ ��� £�� ÁH�� ¢ ©ªæ_�Ư½�i± ¢ £��ë¯6¬v�k± � �«­&�«��úo­&©�� �2 �1 J­&� � ¬  �¢ ±¶©  È¨ ±ü¯°��© �¡ È¨�¸ ¼���ߨÎÁg¨ ©  �1 J # , s4µG1x¸èÅ � ®± 1 ��  �¨ ©   ± � ­&� ¢V è¨ © �Ý��k£ ��&�o� �¡ ë� �4� µY²C¸�� � �¡  � �¬ ¨ ©   »�±Ä¤[©ª£ ¨��¶� ±¶£��t£ ¨C �¢�¨ ­k� � �   ��±   � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � © �6� ±6©   � ®¨ ¯ ¨�¢V  © ¢È� ¤¥± �¬��i±¶¬ ¿ § ¢ �i±6¯½�Ư ¨�¢�¨ °��£�©�»2±6��¯ ¢ �i¯ ¢ � � � ² ¼F(/2�$�ÿ/C� �� � ��% bc_a`ed\ f8g Z[TW\�V8g�i,b�`GZ[TW\ 9S\�1 \$� ` _ � TcTW\0�2��g�² �;� B ²��6#D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 � ï �i©  !� 3 ² �;� B ²�� �   ¬��i©ª� �¡ C³ ± � ¬v�i±6¬ ¿ § ¢ ��±6¯°� � �À � Á ©Æ¯ ¢ �i¯ ¢ � � � ²   �&£Æ»�±¶� � 3�³ �   � ± � ¬���±6¬ ¿ § ¢ �i±¶¯°�Ú¯ ¨�¢�¨ °��£�©�»2±6�µ ¯ ¢ �i¯ ¢ � ¸¹� � ²"  �&£x»�±¶� ³ ¬��i©   ± � ¬v�i±6¬ ¿ § ¢ ��±6¯°� � � À � Á © � � � ¼ ï ©O� �×� �   �1 $ £��   � ¢ ����­k� � ¬  è¨g�2 �� � 1 £���£�� � § � � ��Å�¨ £ª� ¢ ¬�¯½�i± ¢�  �i±   � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �

�ß� � ³ � �㨠ê LNM ��µB1 $ ¸$# LNM " # E$ ��µB1:¸$# ñ� ®±C¯°��± ¢ £ ¨ ¯ ¢ �k��© ®� ¢ � ��&§ ¨ £�©  «���� ��¨ ±   ©�£ª©�¬ �� ÷ ÀO¨ ø Å £ª�k���o���¼Só«¼�«¼ �ë� � ������ � ±6©  »2±6��£q¤¥© �¡ «��k§ ¢�¨ £��+� ¢ Â6©  �¨ £�� � � 1 $ �k¬  *� ±6£�£ª�ã¬v± ¢ £ª�k¬ ��&£ ��&�o� �2  ¬w¬v�k��©�¬�©ª�o¯¶£��k¬¢���&§i±6£�©ª� ¢ ¬ � � ³ ¯ ¨g¢ü÷������ ø ÅL �¦ ¼��'¼l𫼠¨«Å �   æ �_¨ £ª�k��� �¡ �Å ­k�i�����-� µB1 � �@¸ #� µB1 $ � �_¸ºµ�÷ Àx¨ ø Å ¯ ¢ �i¯Ä¼[ù6¼ � ¼ ôiô ¸�Å »2±6� � µG1 � �_¸$# ñ«¼

Page 9: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

î �C£��&�o���'�   £ ¨ ¯ ¢ �i¯½�i¬v©   ©ª� ����� ¼ � ©���¯6£�©ª»�±¶� �¡  »2±6�C£Y¤[© �¡ «��k§ ¢�¨ £ª�J� ¢ Â6©  �¨ £��� � , s°µG1x¸$#>1 J¬&¤ ¨g�6� ±6£�� ¨ ±6¬v¬�©:¬v± ¢È² ��� B ²�� ¼� Á �k­+£��&¬ � �  �¨g  ©ª� � ¬J�   ­&� �¡Á � �¡  ©�� � ¬Cæ¶Ê ��&�k¬¯6£�±¶¬ ¦_¨ ±  üµY� �  �¨ ���o� �2  £��&¬�o�&¬�± ¢ �k¬�¬�± ¢ £ª�k¬   � ¢ �k¬��&£�£�©ª¯   ©ª»2±6�k¬ ¸èÅ � �ü� ©   »2±6� ² ¨UT Z )ag-V$)ag bud\�`ed\ � ¬�©�꯽�i± ¢4  ��±   � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �t� �H­ ¨�¢v¢���H© �¡ «��&§ ¢�¨ Â6£�� ?o� � ²â� �H­ ¨�¢�¨ ­  �®� ¢ �H­k� �«¿ �¢�¨ £ µ ± � ©  �¨ © ¢ � ¸K.ÈÅ ¬�©_� �o� �   � 1 JƱ � ¯6¬��&± � ��­k���&ú�­k©ª� �¡ �� � ?ü�_¨g� ¬*� µq² � .�¸èŨ £�� ¢ ¬µ © ¸ £q¤¥© �¡ «��k§ ¢�¨ £��o� ¢ Â6©  è¨ £ª� � � 1 J��k¬  � ±¶£�£��*¬v± ¢ £��&¬ ��k£ ��k��� �¡  ¬C¬v�k��©�¬�©ª�o¯¶£��k¬¢���&§i±6£�©ª� ¢ ¬ � � � �k£ª£�©�¯   ©�»2±6�&¬É�  µ ©ª© ¸ £Y¤[© �¡ «��k§ ¢�¨ £ª�'� ¢ Â6©  �¨ £�� � � 1 J*�k¬  Ú��&§ ¨ £ª� ¨ ±Ú­k� � �v±¶§i± ��­k�i��¯6£ª��Ê«� � �4IKJ¬�± ¢ £Y¤[� � ¬��&��Â6£�� � �k¬ ��k£ ��&�o� �¡  ¬��k£ª£�©ª¯   ©ª»�±¶�k¬ ¢���k§i±6£ª©�� ¢ ¬ � � ² ¼���¨ºÁ ± µb �¦ ¼ ���¶¸ »�±¶�É£���¯°�i© �¡ Éµ © ¸ �&¬  �  �i±��v�i± ¢ ¬ Á�¢�¨ ©q¼ ��� ¬ ¨ ©   ¯ ¨g¢�¨ ©ª£�£��&± ¢ ¬µY����&�o� � ¬  �¢�¨g  ©�� ��� �É£ ¨ ¯ ¢ �i¯4¼�� Ž÷ î £ªø ¸ »2±6� Å ¬v© · �k¬  H� ��­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � ±6£ª£�� Å£��믽�i© �¡ Æµ ©�© ¸ �k¬  ÈÁ�¢�¨ © ¨ ±6¬v¬�©q¼ï �i©  �� ± � � � ¬��&��Â6£�� � � ¢ �k¯ ¢���k¬�� �¡ è¨��¡  ¬ � �k¬�­&£ ¨ ¬v¬��&¬ � �'­&� � �v±6§ ¨ ©�¬v� �ã� �k¬  � ¢ �k¬º� ¨ Ê«©ª� ¨ ±�Ê � � ² ¼ < ��± ¢º  �i±  �  � ¢ �0� 3�� � ��� �   � � � ��E £Y¤[� � ¬��&��Â6£ª�� �k¬ ��&£ ��k��� �¡  ¬ ¢���k§�±6£�©ª� ¢ ¬ � � � Å � £ª�*§ ¢ ��±6¯°� � � Þ � à £ � � �å�  �� � � £ª�­ ¨�¢v� © �6¨ £ � ��­&��§ ¢ ��±6¯°�g¼ < �i± ¢.  ��±  >��k£ ��k��� �¡  ¬��&�o©ª¬�©ª�o¯6£ª� ¢���k§i±6£ª©�� ¢^� � �²�� �.­k� �2 �¢�¨ £ª©�¬ ¨g  �&± ¢ � Å � �ÿ� �   � � µ;�_¸ £ ¨üÁg¨ £ª�k± ¢'¨ Â6¬v�i£�±6� � � ¢ � ¨ £ª©�¬ ��k� � � Q L µ�*@½µ�� � ¸ � ô ¸8¨ §�©�¬�¬ ¨��¡  ¬�± ¢�³ " Q µq²�¸:�g³ " Q µ � ¸ ¼ < �i± ¢H  �i±   ­ ¨�¢�¨ ­  �®� ¢ �ȱ � © ¿ è¨ © ¢ � . � � � � � � �   � ³ µY²�� � .�¸ £q¤¥�k¬v¯ ¨ ­&� � �&¬�Ç0� � ­   ©�� � ¬ 1>����&æ � ©��&¬o¬v± ¢²��㮨�Ág¨ £ª�k± ¢ ¬ �_¨�� ¬ � »2±6©�¬�� �2  £���­ ¨ £��k��� �¡  ­k� � ¬  è¨��¡  �k¬ Å © �¡Ág¨�¢ © ¨��¡  �k¬C¯ ¨�¢­k� � �v±6§ ¨ ©ª¬�� � ¯ ¨�¢É� �&¬ ��&£ ��&�o� �2  ¬ � � ²Å �  �ÁH�� ¢ ©ìæ_� �¡ 018µ7�8�_¸$#9.ºµG��¸N18µ;�_¸ ¯°�i± ¢  �i±  ��r3 ² �  '  �i±  ��=3n� ¼ ï �i©  �� � £���¬��i±¶¬ ¿ � � ¬��&��Â6£ª� � � � Ç0� ¢ � �� � �k¬¢ �&¯ ¢���&¬�� �¡ �¨��¡  ¬ � �k¬H­&£ ¨ ¬v¬��k¬ � �É­k� � �v±6§ ¨ ©ª¬�� �C� �   � ¢ �&¬�� ¨ Ê«©�� ¨ ±«ÊJ�k£ª£�©�¯   ©�»2±6�&¬k¼���ÿ� �   � ³ à µq²�� � .�¸ £ª�o¬v�i±6¬ ¿ �k¬v¯ ¨ ­&� � � ³ µY²�� � .�¸ Ç0� ¢ � �� � �k¬JÇ0� � ­   ©�� � ¬ 1¯°��± ¢ £��&¬�»2±6�k£ª£��&¬

%� )���� �� � � � O � Q ��� p�q � µ L ¸�� 18µ L ¸�� à L­k� �¡Á � ¢ §���¼ �ë�+�����æ � ©   ± � ¯ ¢ � � ±6©   ¬v­ ¨ £ ¨ © ¢ � �_¨�� ¬ ³ à µq²�� � .�¸ � � ¯½�i¬ ¨��¡  ê

� 1 � � 1 Ã�� �-# % � �� � � � O � Q ��� p�q � µ L ¸N1 �kµ L ¸ 1 à µ L ¸H L Z­k�Æ»2±6© � � �¶� � ®¨o³ à µY²�� � .�¸ ± � �Ƭ  �¢ ±¶­   ± ¢ � � ¤[�&¬�¯ ¨ ­k�t¯ ¢��� ¦ ©�£ªÂ°� ¢v  ©ª� � ¼���×� ©   »2±4¤[©ª£ à+¨ V8g `�� V f�V8_6Z[T b�`ed\ 9S\$��X-Z ghZSX�`+>\,g-\$� ¬�± ¢�² ¬�©:¯½�i± ¢�  ��±   ­ ¨�¢p¿¨ ­  �®� ¢ �J± � ©  è¨ © ¢ � .Ö� � �JÅ ¯½�i± ¢�  �i±  0?k3 � à µq² � .�¸èÅ £ ¨�¢ �k¬  �¢ ©ª­   ©ª� �ü� ��IKJ ®¨

Page 10: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

���²�� ¬v�  �¢ �i± Á � �_¨�� ¬ ³ à µq²�� � .�¸ �   »2±4¤¥� �+¨¶Å ¯°��± ¢(  �i±   ?�ÅS? � �_¨g� ¬ � à µq² � .�¸èÅ

� IKJ �-IKJ � � #UT ñC¬�© ? .# ? �ô ¬�© ? # ? � t

ï ©4£ª��­k� ¢ ¯6¬ � �ë ¨ ¬�� · �k¬  È� ��­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6� � ±6£�£ª� Å � � ¬ ¨ ©  Æµ�÷ î £ªø Å« �¦ ¼ ��¸»2±4¤[©ª£ àÓ¨Ú  ��±��v�i± ¢ ¬o� ¢V �¦ ��§i� �_¨ £ª©  «�� � �k¬o­ ¨�¢�¨ ­  �®� ¢ �k¬w¬v± ¢.² ¼ �ë¨�� ¬ ÷������ ø ů ¨�¢V  ©�� �J¼ � ¼ ¦4Å � � �o� �¡ �¢ �£ ¨ ¯ ¢ �i¯°��¬�©   ©�� � ¬v±6© Ág¨��¡  � µ © �6����&¯°� �6�_¨ ����� �¡ t� �£ ¨ ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©ª»�±¶� � � ·�¸ ê

� 9<?_ØH?½�kÐdÌÎÐ0?@5�� ��� � ���ebO² \$� ` `G\�T ���e\ AZ�� )uV��g4`GV�u` ? 3 � à µq²�¸ !�TW\^X-Z ghZSX�`+>\,g \ 9S\�? \$� `2TWVYX-Z[TW\,]^\,_a` bc_a`ed\ f8ghZSi�TW\\�` i"�t²mZ T Z )ag V$)ag bud\�`ed\ � !Z[TWV8g;��b�T��/Z/V8g,`�� V f�V8_6Z[T b�`ed\ 9S\$��X-Z ghZSX�`+>\,g \$� �2��gº² #� ¼ KJ?_9QØ��-0?:Õi36;x1 ØO9<?:ÕQÍL/��/2Ì�-0/�Ï_9<?@;OØH/�-0Ð05 �/�3¶Ð09</��JF(/��C9 �/��k;O-dÌÎ3¶ÌQ�7x/�FH/2�ÿ36Ðd9</

ï �i©ª� �¡ J· ± � ­k� ¢ ¯6¬t£���­ ¨ £ � �o­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � � �Ú� ±6£�£ª�C�   # ± � � �¡  ©�� ¢¬  �¢ ©�­   �&�o� �2  ¯°�i¬v©   ©ªÇ Å »2±4¤[� � ­&� � ¬v© �4®� ¢ ��æ¶Ê ��k¬+¯ ¨�¢ £ ¨ ¬�±¶©   �g¼ ���>� �   ����£q¤ ¨��6� � ¨ ± � �k¬�� �¡  ©�� ¢ ¬ � � ·�Å � �B£q¤¥© ���� ¨ £�� ¨ Ê«©ª� ¨ £ � ���B�   � � æ¶Ê«�ã± � �± � ©ìÇ0� ¢ ��©�¬ ¨��¡  � ? � � � · ¼ ���ã� �   �!���ߣª�t¬v�i±6¬ ¿ § ¢ �i±6¯½�t­&�i��¯ ¨ ­   � ¨ Ê«©�� ¨ £²J³�´¶µ �� ¸�� � ²t³�´_µq·�¸ �   ¯½�i± ¢�  �i±   í 3 � � � ��� �   ������ £��J¬��i±6¬ ¿ § ¢ �i±6¯½�� �C­k� � § ¢ ±¶� � ­&� � � � © Á � ¨ ±*í � � ²t³�´¶µq·�¸ »2±6©��&¬   ¯ ¨�¢ë����&æ � ©   ©ª� � £�� � � ࡨ ±� ��£ ¨ ¯ ¢ � �v�k­   ©�� � ��� . ²J³�´¶µ �� �7� �� ¸ ¼ ���>� �   �5� µY²J³�´«µq·�¸ � � �� ¸ £ ¨¬��i±¶¬ ¿p¨ £�§ ®�& ¢ � � � º�&­54�� � � � µq²t³�´«µY·C¸v¸ Ç0� ¢ � ��&� � �&¬.Ç0� � ­   ©�� � ¬w»2±6©�¬v� �¡ Â6© ¿ © �¡Ág¨�¢ © ¨��¡  �&¬�¯ ¨�¢ ���� ¼ < �i± ¢ ± �Ú  �k£�­k� ¢ ¯6¬ · � � ­k� � ¬�© �4®� ¢ � � ¤¥± � �CÇ ¨��­&� �§ �� ���� ¢�¨ £���ê�¬v± ¢ £���­&� �¡ �¢ � �Ý� � ²t³�´6µY·C¸ © � � �¡  ©ìæ �� ®¨· � £ ¨ �o�&¬�± ¢ � � �! ¨i¨g¢�� ¯½�i± ¢ £ ¨ »2±6�&£�£���� �� �k¬  .� � Á ��£�±6��� ��&§ ¨ £ ®¨ ô Å ¬�± ¢w²t³�´_µq·�¸ £ ¨ �o�&¬�± ¢ �� � ¨i¨g¢!�� ¯½�i± ¢ £ ¨ »2±6�k£ª£��4��� �&¬  �� � Á �i£�±¶�o� ��k§ ¨ £ ®¨ ô �   ¬�± ¢t  �i±  Æ  � ¢ �� ¨ ʶ©ª� ¨ £¡�k£�£ª©�¯   ©�»2±6�1� £ ¨ �o�&¬�± ¢ � � �2 ¨i¨�¢ L   �k£ª£��(»2±6��� ��� ¬��i©  8� � Á �i£ª±6�����k§ ¨ £ ®¨ ô ¯½�i± ¢ £ ¨ ���k¬�± ¢ �t»�±¶�   ©ª� �¡ � L �8�� ¼ ï © � �&¬   ± ����k£ ��k��� �¡  �k£ª£�©�¯   ©�»2±6�¢���&§i±6£�©ª� ¢�� � ²J³�´¶µq·�¸ �  01 3 � µY²J³�´¶µq·�¸�¸ �i± 1 3 � µY²J³�´¶µq·�¸ � .�¸ ¯°��± ¢ ± �­ ¨�¢�¨ ­  �®� ¢ � . � � �JÅ � µB1 � �@¸È����k¬�©ª§ � �£q¤¥© �¡ «��k§ ¢�¨ £���� ¢ Â6©  è¨ £ª� � � 1 ¨ ±$¯½�i© �¡ ��¯°��± ¢ £ª�k¬¹���k¬v± ¢ �&¬ ¨ © � ¬�©½­ ¦ �i©�¬v©��&¬k¼ ï © ? �k¬   ± � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� �+� � ²J³�´¶µq·�¸� �+¨ ¯6¯½�k£ª£�� _eb548\-ZI��� � ? µY� �  �¨g  ©ª� � # "��½µ;?8¸v¸ £��ë¯6£ª±6¬�¯½�   ©   � �¡  ©�� ¢?W   �&£4»2±6�?�¨ ©   ± ��Á �&­   �&± ¢ æ«Ê¶�Ȭ���±6¬*���� Å«¨�Á �k­È£ ¨ ­&� �¡Á � �¡  ©�� � � � # ���8¼ À � � © Á � ¨ ±� � ? �&¬  (¨ ±¶¬�¬�©¶£��¹¯¶£�±6¬�¯½�   ©   � �¡  ©ª� ¢(W   �k£¶»2±6� ? © �6� ±6©ª¬���± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �� � � © � � �¡  ©ª»�±¶�k��� �¡ È� ±¶£�£�� � ��� µq²t³�´¶µq·�¸ �-���� ¸ ¼

Page 11: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �

���Ý� �   ��� � £��Ú¬��i±6¬ ¿ § ¢ �i±6¯½� � � ²J³�´6µq·�¸ Ç0� ¢ � �� � �&¬�� ¨< �¢ ©ª­k�&¬ �_¨g� ¬²J³�´¶µ �� ¸ »�±¶©_¬�� �¡ H �¢ © ¨�� §�±6£ ¨ © ¢ �&¬L¬v±6¯ �� ¢ ©��&± ¢ �&¬���� � ±6£�� � ��¼ ��� ¯°��¬�� ¨ ±6¬v¬�© ů°��± ¢�  �i±   � �¡  ©�� ¢ ¬  �¢ ©ª­   �k��� �¡  ¯½�i¬�©   ©ªÇ W�Å � �� # ô�� ? �� � ���   ¯ ¨�¢ ­k� �¡Á � �«¿  ©ª� � � � # � � �   � �� �   ��� µq²t³�´«µY·C¸ ��� �� ¸ £q¤¥�k¬v¯ ¨ ­k� � �&¬�Ç0� � ­   ©�� � ¬�£���­ ¨ £ª� ¿�o� �¡  ­k� � ¬  è¨��¡  �k¬ ®¨ ¬�±6¯6¯½� ¢V  ­k�i��¯ ¨ ­   ¬�± ¢H²t³�´6µY·C¸ »2±6©_¬v� �¡  Â6© ¿ © �¡Ág¨�¢ © ¨��¡  �k¬¯ ¨�¢ � �� ¼ < ��± ¢�  �i±   � �2  ©�� ¢ ¯°�i¬v©   ©ªÇ W � �ü¨ ê� ��� �� \ � �� \ � �� tï �i©   � ¨ © �¡  � �6¨��¡ (³ ± � ­&� ¢ ¯6¬(£���­ ¨ £ � � �w¨�¢ ­ ¦ ©ª� �� � ©�� �� �º­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6�� ±6£�£ª��¼ ����¨�� ��¯   ��£ª�k¬�����k���k¬ � �  �¨g  ©ª� � ¬�¯½�i± ¢H³ ¼ ï ��©  1W ± � � �¡  ©ª� ¢ ¬  �¢ ©�­   � ¿�o� �¡  ¯°��¬�©   ©ªÇp¼ ���Æ� ©   »�±¶� · �  O³ ¬v� �¡  Ww¿ í M76�� � QYX ¬&¤[©ª£ àƨ ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�� ¤ ¨��6� � ¨ ±«Ê �� � � �� � � � � ¼ ��� æ¶Ê«� ¨ £�� ¢ ¬�± �  �¢ ©�¯¶£��  .µ �� � � � ? � � ? ¸� ®± �� � � ê �� � � �� . � � � � �k¬   ± � ©�¬����o� ¢ ¯ ¦ ©ª¬������  �? �k¬   ± � �o± � © ¿Ç0� ¢ ��©�¬ ¨��¡  � � � ³Ó  �k£ª£���»2±6� �� � � µ � � � XYX6Q Q ? � ¸$# � � � XYXYQ Q ? ¼ï © ³ �&¬   ± � ­k� ¢ ¯6¬�£���­ ¨ £ � � � ¨�¢ ­ ¦ ©�� �� � ©ª� ��� � ­ ¨g¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±6£�£ª�  �&£�»2±6� · �  ü³ ¬��i©ª� �¡  Ww¿ ¯ ¢ ��­ ¦ �k¬ ¨ £ª� ¢ ¬ �� � � © �6� ±¶©   ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�� ¤¥�k¬�¯ ¨ ­k�&¬ Á �k­   � ¢ ©��k£ª¬ � � � µY²J³�´«µq·�¸ ��� �� ¸ ¬�± ¢ � µq²t³�´¶µq³¹¸ ��� � ¸èÅ ©�¬v�i��� ¢V¿¯ ¦ ©ª¬���� ����k¯½� �6�_¨g�2 �� ±×­ ¦ �i©ìÊ � � ? �ÿ�  0? µ æ«Ê ��&¬ �_¨g� ¬�£ ¨ ¬v±6©   � ¸ ¼ î �   ©ª¬�� ¿�o� ¢ ¯ ¦ ©ª¬���� � ¤¥�k¬v¯ ¨ ­k�&¬ Á �k­   � ¢ ©ª�k£ª¬È�&¬   � � Ç ¨ ©   ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� � ¤ ¨ £�§ ®�& ¢ �&¬µ ¯ ¢ �i¯½�i¬�©   ©�� � 𫼠ô ¼ ô Ž÷¥À � ô ø ¸ ¼ Àx¨ë¢ �k¬  �¢ ©�­   ©�� �� ��­&�   ©�¬v�i��� ¢ ¯ ¦ ©�¬���� ®¨ £ ¨ ¬��i±6¬ ¿¨ £�§ ®�k ¢ � � µY²J³�´¶µq·�¸ � � �� ¸�� �/� µY²J³�´¶µq·�¸ ��� �� ¸ © �6� ±6©   ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�� ¤ ¨ £�§ ®�& ¢ �&¬ëê �� �� êS� µq²t³�´6µY·C¸ � � �� ¸/. � µq²t³�´¶µq³¹¸ � � � ¸µ ¯ ¢ �i¯½�i¬�©   ©�� � ð«¼l𫼠ô ÷ À � ô ø ¸ ¼ � �Æ �¨��¡  »�±Ä¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� � ¤[�&¬�¯ ¨ ­&�k¬ Á �&­   � ¢ ©��&£�¬ Å�� �� �k¬  º�����æ � © � �Æ£ ¨ Ç ¨��­&� � ¬�±6© Ág¨��¡  �ê< ��¬�� � ¬

� � # D * # µ � � ¸ � � 3�²t³�´_µq·�¸ ê � � #�� � ?�� �� Z � ��� � à � t tWt�� � ´ F� ®± � � º�k¬   £��ë¬ à ��°��£�� � � �ë¢ � � � 4�� ¢ ¼ ���ר¨ £ª� ¢ ¬

²J³�´¶µq·�¸$#�� � )���� ��� * ��� t< ��¬�� � ¬

ý � � � #�²t³�´6µ �� � � �� ¸ ��²t³�´_µ �� � � �� ¸ tï �i©  * 3 � �L¼ ï © µ ����! ¸@3 ��� � ��� Åx¨ £�� ¢ ¬�� �� � * ! � � �� � � ����k¯½� �6�»2±6� � ��£ ¨ ­k£ ¨ ¬�¬v� µ ���� �! ¸O� � µ � ��! ¸O�6¨�� ¬ ý � � � ¼ ��� ¯½�k±  �� � � ­ ����&æ � © ¢ ¬ ¨�� ¬¨ ��Â6©ª§i±#" �  «�� ���� �� * �! � ���� ¯°�i± ¢.  �i±  $µ ���� �! ¸A3 ý � � � ¼ �º�   � � ¬+� ¨ © �«¿  � �_¨��¡ %$ � � � � � £Y¤[� � ¬��&��Â6£�� � �k¬C­&�i±6¯6£ª�k¬ µ ���� �! ¸ 3 ý � � �   �k£ª¬�»2±4¤¥©�£¹�ÒÊ«©�¬   �± �Ö¢ �k¯ ¢���k¬�� �¡ è¨��¡  � � � �� �_¨g� ¬ ²t³�´¶µ �� ¸ �   ± �Ö¢ �k¯ ¢���k¬v� �¡ è¨��¡  ! � � �!�_¨�� ¬ ²J³�´¶µ �� ¸'  �&£�»2±4¤¥� �B¨ ©   � * # * !¼�� � ��k­ ¢ © Ág¨��¡  ­&�  v  � ¢ �k£ ¨<  ©�� �

Page 12: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �� * ! � # * � �oÁ��� ¢ ©ªæ_�È»2±6� $ � � � � � �&¬   ± � ¬���±6¬ ¿ § ¢ �i±¶¯°� � � ý � � � ¼ < �i¬v� � ¬� � æ � �

ý � � � � � # ý � � � � $ � � � � � tç � ¬�©ª�o¯¶£���­ ¨ £�­&±6£:�o� �2 �¢ �ë»2±6�

��� * ��� # � ������ ��� ) � � � � � � � ���� *

�! � � �� t

� © �6¨ £��&�o� �2  � �㨠��   � � ±ã£ ¨�����&­k�i��¯½�i¬�©   ©�� �µqD���¸ ²J³�´6µq·�¸$# �� ) ��� �

� ���� ��� ) � � � � � �� �� �

� *�! � � ��

��� � � ���� � ±6©   »2±6�õ£Y¤[� � ¬��&��Â6£ª� � �k¬�Ç0� � ­   ©�� � ¬×­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6�k¬ � �k¬�� �«¿¬��&��Â6£��&¬'­&�i�o¯ ¨ ­   ¬�� �� �

� *�! � � �� Å ¯½�i± ¢t  �i±  �� * � µ ���� �! ¸��¡Å&* 3 � � �  

µ����

�! ¸A3 �

ý � � � � � Å �k¬   ± � �ß ¨ ¬v� ¨ £�§ ��& ¢ ©ª»�±¶� � � � µq²t³�´¶µY·C¸ � � �� ¸ ¼ ���¢�¨ ©ª¬�� �¶� � � �×£ ¨ ����k���+Ç ¨ �­k� � ¯½�i± ¢o²t³�´¶µq³¹¸�Å � �>¨�� �i¯  è¨g�2  £��&¬ � �  è¨g  ©�� � ¬¨��_¨ £ª�i§i±6�&¬k¼ é ¨ © �¡  � �6¨��¡  ©ª£ àÓ¨ ± � �+Â6©��v�&­   ©�� � � � ê � � � »2±6©�� �«¿Á �i©ª� " � �°µ;? ���� � ? ���� � t tWt ? ���� ¸ ¬�± ¢U " � �ĵ�? ��� � ? ��� � tWtWt ? ��� ¸èÅ �   ¯½�i± ¢.  �i±  �* 3� � ± � �ÿÂ6© �v�k­   ©�� ���_¨<  ± ¢ �k£�£ª� � �� ê

�ý � � � � �

�ý � � � � ��� � � � © �6� ±6©   �Ú¯ ¨�¢£q¤¥©�¬v�i�o� ¢ ¯ ¦ ©ª¬���� ²J³�´_µ �� � � �� ¸ �(²J³�´¶µ �� � � �� ¸ ²t³�´¶µ � � � � ¸ �(²J³�´¶µ � � � � ¸ ¼À ¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� �� �� �&¬  È� � �6����t¯ ¨�¢�� �� µ"� ' �� �� � ��! � ' �� ¸ # � ' �� �� �"� ��� � � � �� � � ' ��

¯°��± ¢É  �i±   * 3 � �Ú�  Jµ ���� �! ¸ 3 �ý � � � � � Å � ®± µ �� � � �!�� ¸$#�� �� µ�µ

����

�! ¸�¸ ¼

ï ©$# �k¬   ± � �$¯ ¨�¢V  ©��Ú­k���o¯ ¨ ­   � � � ²t³�´6µY·C¸ Â6© ¿ © �¡Ág¨�¢ © ¨��¡  �߯ ¨�¢ � �� Å£q¤¥©�� ¨ §i��¯ ¨�¢ �� �� � ��£ ¨ Ç0� � ­   ©�� � ­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � �%#%�k¬   £ ¨ Ç0� � ­   ©�� � ­ ¨�¢p¿¨ ­  «�� ¢ ©�¬   ©�»2±6� � ¤¥± � ¬���±6¬ ¿ � � ¬v�k��Â6£ª��­k�i��¯ ¨ ­  '& � � ²J³�´¶µq³¹¸ Â6© ¿ © �¡Ág¨�¢ © ¨��¡  ¯ ¨�¢��� �   � � ¯°��¬���¯ ¨�¢�����&æ � ©   ©ª� � �� �� µ # ¸(#(& ¼ �ë��¨ë¨ £ª� ¢ ¬ � 6 � µ # ¸$# � 6�� µ)&¸¬�©:£ª�k¬����k¬�± ¢ �k¬È¬�± ¢º²t³�´6µY·C¸ �  º²J³�´¶µq³¹¸ ¬�� �¡  ­k�i�����ë¯6£�±6¬ ¦6¨ ±   ¼ï �i©   � ¨ © �¡  � �_¨��¡ �? ± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � © ¢v¢��� � ±6­   ©�Â6£ª� � � � © Á � ¨ ±C© � Ç �� ¢ ©��k± ¢�i± ��k§ ¨ £ ®¨ W � � ²t³�´¶µq·�¸ �  t� �   � � ¬+*�J*£q¤¥�k¬v¯ ¨ ­&� � ��£ ¨.¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ? ¼��£ª� ¢ ¬:£Y¤ ¨ £ª§ ®�k ¢ � � µY²J³�´«µq·�¸ �-� �� ¸Ä¨ §�©   ¬v± ¢ £q¤¥�k¬�¯ ¨ ­k�,* ' ��J � �k¬ Á �k­   �&± ¢ ¬Oæ¶Ê«�k¬¬��i±¶¬0� �J ¯ ¨�¢ 18µ �6¸$#9?�µB1x¸èµ �6¸¯°��± ¢ë  �i±   1 3 � µq²t³�´6µY·C¸ � � �� ¸ �  t  �i±   � 3 * ' ��J ¼ À ¤¥�k¬v¯ ¨ ­&�-* ' ��J �k¬  ¨ © � ¬�©8�'± � © � ¤¥± � �¬  �¢ ±¶­   ± ¢ � � �4� µq²t³�´6µY·C¸ � ���� ¸q¿ �o� � ±6£ª� ®¨ § ¨ ±6­ ¦ ��¼ ���� �   �.*eJ � / � � £ª�5� µq²t³�´«µq·�¸ � ���� ¸q¿ �o� � ±6£ª�0* ' ��J ¯°�i± ¢ £�� � ©21 �� ¢ � �2  ©�� ¢.� ±� ¿ �k¬v¯ ¨ ­&�3* ' ��J ¨�Á �&­×£ª�k»2±6�k£�©ª£�­k� " � � ­k© � �+� � ¬v�k��Â6£ª©�¬   �k��� �¡  ¼ ��� ¬ ¨ ©   »2±6�*eJ � / � � �&¬   ± � � µq²t³�´6µY·C¸ � ���� ¸q¿ ��� � ±6£�� � � ��� ±6£@© ¢�¢��� � ±¶­   ©ªÂ6£��¹�   »2±6� ?�4.*eJ � / � � © �¶� ±6©   ± � ��Â6© �v�k­   ©�� � � �¡ �¢ ��£Y¤[� � ¬��&��Â6£ª� � �È­k£ ¨ ¬�¬v�k¬ � ¤ ��k»2±6© Ág¨ £�� � ­k� � �¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬Æ© ¢v¢��� � ±6­   ©�Â6£ª�k¬ � � ²t³�´6µY·C¸�� � � © Á � ¨ ±ß© � Ç �� ¢ ©ª�k± ¢ �i± ��k§ ¨ £ ®¨

Page 13: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

�B�W �   £q¤¥� � ¬v�k��¶£�� � �k¬�­&£ ¨ ¬v¬��&¬ � ¤¥©�¬v�i�o� ¢ ¯ ¦ ©ª� � � � µY²J³�´¶µq·�¸ � � �� ¸Y¿ ��� � ±¶£��k¬© ¢v¢��� � ±6­   ©�Â6£ª�k¬k¼ é ¨ © �¡  � �6¨��¡ �Å £q¤¥©�¬v�i�o� ¢ ¯ ¦ ©ª¬���� �� �� ê�� µY²J³�´¶µq·�¸ � � �� ¸ � µq²t³�´«µq³¹¸ � ��� ¸ © �¶� ±6©   ± � ©�¬v�i�o� ¢ ¯ ¦ ©ª¬���� µb� �  «��   �i±��v�i± ¢ ¬ �� �� ¸ � �¡ �¢ �H£Y¤[� � ¬��&��Â6£��� �k¬J­k£ ¨ ¬�¬v�k¬ � ¤¥©�¬v�i��� ¢ ¯ ¦ ©�� � �/� µq²t³�´«µY·C¸ � � �� ¸q¿ ��� � ±6£��&¬Æ© ¢�¢��� � ±¶­   ©ªÂ6£��&¬J�  £q¤¥� � ¬v�k��¶£�� � �&¬x­k£ ¨ ¬�¬��&¬ � ¤¥©�¬����o� ¢ ¯ ¦ ©ª� � � � µY²J³�´¶µq³¹¸ � � � ¸Y¿ ��� � ±¶£��k¬Ä© ¢�¢��� � ±¶­   ©ªÂ6£��&¬k¼� � � ­�£q¤¥©�� ¨ §i��¯ ¨�¢ �� �� � �º£ ¨ ­k£ ¨ ¬�¬v� � ¤¥©�¬v�i�o� ¢ ¯ ¦ ©ª� � � *eJ � / � � �k¬   ± � ��­k£ ¨ ¬�¬v�� ¤¥©�¬����o� ¢ ¯ ¦ ©ª� � �5� µq²t³�´¶µq³¹¸ � � � ¸q¿ ��� � ±6£��&¬w© ¢�¢��� � ±6­   ©�¶£��k¬o�   �&£�£��ã­k� ¢v¢ � ¿¬�¯½� �6��®¨ ± � ��­k£ ¨ ¬�¬v� � ¤ ��&»�±¶© Ág¨ £�� � ­k� ! � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬(© ¢�¢��� � ±6­   ©ªÂ6£��&¬ � �� © Á � ¨ ±Æ© � Ç �� ¢ ©��k± ¢ �i± ��k§ ¨ £ ®¨ W � � ²J³�´6µq³¹¸ ¼ ï ©#! �C�&¬   £ ¨ ­&£ ¨ ¬v¬�� � ¤ ��k»2±6© Ág¨ £�� � ­k�� ��£ ¨�¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � ?�Å � � ¯°�i¬v� �� �� µ ! � ¸(# ! ¼ < ¨�¢ ­k� � ¬ ��k»2±6� �¡ �Å �� �� © �«¿� ±6©   ± � ��Â6© �v�k­   ©�� �ë� ��£q¤¥� � ¬v�k��¶£�� � �&¬x­k£ ¨ ¬�¬��&¬ � ¤ ��&»2±6© Ág¨ £ª� � ­&� � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬£�©ª¬�¬��&¬ã© ¢�¢��� � ±6­   ©ªÂ6£��&¬ � � ²J³�´¶µq·�¸.� � � © Á � ¨ ±Ý© � Ç �� ¢ ©ª�k± ¢ �i± ��&§ ¨ £ ®¨ W ¬v± ¢£q¤¥� � ¬v�k��¶£�� � �&¬x­k£ ¨ ¬�¬��&¬ � ¤ ��k»2±6© Ág¨ £ª� � ­&� � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬x£�©ª¬�¬��&¬:© ¢v¢��� � ±6­   ©�Â6£ª�k¬� � ²t³�´¶µq³¹¸È� � � © Á � ¨ ±Ú© � Ç �� ¢ ©��&± ¢ ��± ��&§ ¨ £ ®¨ W � Â6© �v�k­   ©�� � »�±Ä¤[� ��Ág¨.  �i± ¿�v�i± ¢ ¬ � �   � ¢ �� �� � �   ¯½�i± ¢�  ��±   � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �4?×� � � © Á � ¨ ±w© � Ç �� ¢ ©��k± ¢ �i±��k§ ¨ £ ®¨ W � � ²t³�´6µq·�¸èÅ ¯½�i± ¢É  �i±  01 3 � µY²J³�´¶µq·�¸ � � �� ¸èÅ � �רLNM �� �� µ;?8¸èµ �� �� µG1x¸�¸(# LNM ?HµG1x¸ tû �&� ¨g¢ »2±6� � ¬*»2±6� Å ¬�© �m3 ! Å ©�£ à>¨ ¯ ¨�¢ ­k� � ¬  �¢ ±6­   ©�� � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�� � � ¿ �k¬�¯ ¨ ­k�&¬ Á �k­   � ¢ ©ª�k£ª¬ü� �¡ �¢ � * ' ��J �   * ' ��

�Å ¯¶±6©�¬v»�±¶�$£Y¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o��� �� ê6� µY²J³�´¶µq·�¸ � � �� ¸ � µY²J³�´¶µq³¹¸ �-� � ¸ �&¬   ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� � �4� ¿¨ £�§ ®�k ¢ �k¬k¼

� �Ư6£�±¶¬ Å £Y¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o��� �� êS� µq²t³�´6µY·C¸ � � �� ¸ � µq²t³�´6µY³É¸ � � � ¸© �6� ±6©   ¯ ¨�¢:¢ �&¬  �¢ ©�­   ©ª� � ± � ©�¬v�i��� ¢ ¯ ¦ ©�¬����(� µq²t³�´¶µq·�¸ �-� � �� ¸ � µY²J³�´«µq³¹¸ � � � � ¸»2±6© � ¤[�&¬  C¨ ±  �¢ �w»2±6�.£Y¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� �� � �� ­k� � ¬  �¢ ±6©  ü®¨ ¯ ¨�¢v  © ¢Æ� ±  �¢ ©�¯¶£��  µ �� � �� � ? � � ? ¸ � ®± �� � �� ê �� �7� � �� � � � � � �k¬   £Y¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�º© �«¿� ±6©   ¯ ¨�¢� � �� � � ê �� � � �� � � � � µ ¯ ¨g¢ ­k�ü»2±6�×£ª�k¬ ����k­&�i��¯°�i¬v©   ©�� � ¬µ � � ¸ �  $µ � � ��¸o� � ²t³�´6µq·�¸ ¬�� �¡  ­k�i��¯ ¨g  ©�Â6£ª�k¬ ¸ ¼ î �&£ ¨ ©���¯6£�©ª»2±6��»2±6��� �� µ;?L¸�¨ £ª�ë����&�o� � © Á � ¨ ±ü»�±¶� ? ¼� 9<?_ØH?½�kÐdÌÎÐ0?@5 � ����� � �eb7W � ð ! �� �� g d\ Z[T b:��\[��_ \ki,b 3,\ X�`;b7V8_l\,_a`;g \ TW\$�X�T Z�;��\$� 9&% d\V����b54oZ[TW\,_ X \ 9S\$�Ag \8)ag d\$��\,_a`7Z[`;b7V8_'� f�d\,_�d\,g b����e\$� bcg g(d\V9I��X�`;b7i�TW\$� 9S\²J³�´¶µq·�¸�9S\0_eb548\-ZI�4bc_��(d\,g b7\*� g0V� d\ f[Z[T@>Z7W � ô \�`$TW\$�@X�T Z�;��\$��9&%-d\V����b54oZ[TW\,_ X \9S\$� g \8)ag d\$��\,_a`7Z[`�b7V8_'�f�d\,_ d\,g b�����\$��bcg g(d\V9I��X�`;b7i�TW\$�19S\�²J³�´¶µq³¹¸�9S\ _eb548\-ZI��bc_��(d\,g b7\*� gV� d\ f[Z[T >Z W � ô #D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �����¨ ��Ê«¯6£�©ª»2± ��'¯6£ª±6¬ ¦_¨ ±   »2±6��£ ¨ Â6© �v�k­   ©�� � �� �� �k¬  £ ¨Ú¢ �k¬  �¢ ©�­   ©�� �⨠±«Ê ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬ � � ²t³�´6µY·C¸�� � � © Á � ¨ ±>© � Ç �� ¢ ©ª�k± ¢ �i±��k§ ¨ £ ®¨ W � �w£ ¨ Â6© �v�k­   ©�� � � © �¡ �¢ � � ±6©   � ¨ ±ÿ­ ¦_¨ ¯¶©  �¢ � ô � � ÷ À � ô øY¼ ���õ¨ ¯ ¿¯6£�©ª»2±6� � � � ­È£���­&� ¢ ��£�£ ¨ © ¢ � � ¼ � ¼ �Æ� � ÷ À � ô ø   � �_¨��¡  ­k�i��¯   � � ±Ç ¨ ©   »�±¶�º¬v©½± � �¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ? ¨ ± �üÁ �&­   �&± ¢� æ«Ê¶�J¬��i±¶¬@� � �� � �&¬  ë¨ ±6¬�¬v©O± �ãÁ �&­   �k± ¢

Page 14: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �æ¶Ê«� � � ? ¬v�i±6¬ � � �� ¼���ÓÁg¨ � ¨ © �¡  � �_¨��¡ ¢�¨ ¯6¯°�&£�� ¢ ± �Ó¨ ±  �¢ � ¢���k¬v±6£  �¨g � � À �k� ¨ © ¢ �.»2±6©�­k� ��¿­k� ¢�� �º£���­k�i��¯½� ¢v  �k��� �¡ (� �k¬�© �¡ «��&§ ¢�¨ £ª�k¬H� ¢ Â6©  �¨ £��&¬��k£�£ª©�¯   ©�»2±6�&¬ � �k¬(Ç0� � ­   ©�� � ¬¬��Æ­k� ¢�¢ �&¬�¯½� �6�_¨g�2  ¬�± ¢È� �k¬�­k� ¢ ¯6¬�¯ ¢ ��­ ¦ �&¬k¼ï �i©  2� ± �>��k£ ��k��� �¡  �k£ª£�©ª¯   ©ª»�±¶� ¢���&§i±6£ª©�� ¢�� � ²t³�´6µY·C¸ ¼ ï �i©ª� �¡  ê¿�· E�# ·o÷ � ø4£ª�ë¬��i±¶¬ ¿ ­&� ¢ ¯¶¬º� ¨ Ê«©�� ¨ £ � ��� ´6µY·C¸ � � §i� �¶�6¢���t¯ ¨�¢��½Å¿ Q £Y¤[© �6� ©�­&� � � ¢�¨ ��©ªæ_­ ¨g  ©ª� � � �ü£q¤¥��Ê   � � ¬�©ª� �ݵb� � � �&§ ¢��� # ¸'� �ã­k� ¢ ¯6¬

£���­ ¨ ±�Ê � � �ü¨�¢ ­ ¦ ©�� �� � ©�� � ¬ · E ��·Å¿�� £Y¤[± � ©�»2±6� �� ¿ � ¢v�6¢ � ¦��� ¢��� � ©  è¨ © ¢ � � ��� ´_µY·C¸(� � ¢ � ¨ £�©ª¬ ���¯ ¨�¢È· �E Å¿ ��� £�� ¢�¨g� ©�­ ¨ £ � �t¾ ¨ ­&�iÂ6¬v� �×� � �ÉÅ¿��� £ ¨�Á�¨ £�± ¨g  ©�� � ¬�± ¢ � ´6µY·C¸�����&æ � ©ª��¯ ¨�¢��@µ��ĸ2# � ¨ Ê D "03 3 ê �=3� �� F2Å¿ ¯½�i± ¢�  �i±   O 3�3�Å� ���# D � 3�� ê ��� �=��� 3�� �� F2Å¿ O �# � ¨ Ê D O 3�3 ê �� .\ �� � � ���'F2Å¿ O � # O �����@µ;�_¸¿ �O � # O � � Q Å¿,*n# � � �� �� �� J ¼� ©�ʶ� � ¬Æ± � ­ ¨�¢�¨ ­  �®� ¢ � ¨��6� ©   ©ªÇ�� � � � · � ��­k� �¶� ±6­   �k± ¢�� � µb �¢ © Á © ¨ £�¬v± ¢

� �ß�  �� � �ü �¢ © Á © ¨ £Ä¬v± ¢ �� ¸ ¼ ï �i©  � # D � 3 � ´6µY·C¸ ê LNM µ����_¸ 3 ORQ M µ � � ¸ Z `��/3�*0FSt

ï �i©  �W ± � � �2  ©�� ¢ ¬  �¢ ©�­   �k��� �¡  ¯°��¬�©   ©ªÇp¼ ï �i©�� �¡  ê¿�W � # W � µ�� � W׸ £��C¯6£ª±6¬Æ¯°�   ©   � �¡  ©ª� ¢ ¬�±6¯ �� ¢ ©ª�k± ¢ �i± ��k§ ¨ £ ®¨ � ¨ Ê D ô���O � Z W � �O �2F2Å¿/W � � #�W � � µ�� � W׸ £ª��¯6£ª±6¬¹¯½�   ©   � �¡  ©ª� ¢ ¬v±6¯ �� ¢ ©��&± ¢ ��± ��k§ ¨ £ ®¨ W � µ;� � W׸ ��O � �Bô ¼ý Í �/2?@9«þ/2�ÿ/ � � � � � � V8b�`0� ��_ d\�T d\,]^\,_a` \�TcT b )6`�b�����\ g d\ f�uT b7\,g 9S\+²J³�´¶µq·�¸\�` W � _>\,_a`�b7\,g � `�g b7X�`B\,]^\,_a`G)uV � b�`�b �*# �@TWV8g;� TW\ 48V8b:� bc_6ZFf�\ * µ;� � W׸ 9S\ �90d\�� _eb ) Z g * µ;� � W׸ #l�°µ ô � ? � � � E � � �� � ¸�\$� `2X V8_a`G\,_ � 9�Z _'��T % \,_'��\,]^i�TW\ 9S\$�d\�T d\,]^\,_a` ��\�TcT b )6`;b�����\$��g d\ f�uT b7\,g;��9S\�²t³�´6µY·C¸�\�` 4*d\,g b�� \Z�� * µ;� � W׸5\$� `Ui,b �Bbc_ 4oZ g b;Z _a`0) Z g � � � �

� \�`0)uV� gA`BV� `G\ �,V8_ X�`�b7V8_n1 3� µq²t³�´«µq·�¸ � � �� ¸�T % bc_a`ed\ f8g Z[TW\�V8g�i,b�`GZ[TW\ 9S\�1 \$� `*X V8_'� `GZ _a`G\ d\ f[Z[TW\ >Z � µB1 � �_¸�2� g * µ;� � W׸��i"�G)uV��g�`GV� `*X V8gS) �ɳ W � � � )ag-VYX�� \�9S\�· ! �� � � �� µ * µ;� � W׸v¸0\$� `(bc_ X�T ����\�9�Z _'�T % \,_'��\,]^i�TW\ 9S\$�>d\�T d\,]^\,_a` �4\�TcT b )6`;b�����\$�4g d\ f�uT b7\,g;� 9S\�²t³�´6µY³É¸ \�`�)uV��g `GV� `B\

�,V8_ X�`;b7V8_5193 � µY²J³�´¶µq·�¸ � � �� ¸"!�T % bc_a`ed\ f8g Z[TW\ V8g i,b�`7Z[TW\ 9S\ �� � � �� µB1x¸4\$� `�X V8_ �� `GZ _a`G\ d\ f[Z[TW\ >Z � µG1 � �_¸��2� g �� � � �

� µ * µ�� � W׸�¸$#

Page 15: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �¹¨�¸L����¨ ��� � �

� \ � � � � �� �   � �¨ ¯6¯6£ª©�»2±6�É£ª�  �¦¹��k� ¢k®�k���� �Æ£ ¨ ¯ ¨ §i� ô ñ�ù2ð � � ÷ À � � øY¼

 ¸É���ü¨ 153 � µq²t³�´6µY·C¸ � � �� ¸ # 1 3 � µY²J³�´¶µq·�¸ ��� �� ¸-t���㨠¯6¯6£�©ª»2±6� ®¨C� �i± Á � ¨ ±ã£��  �¦���k� ¢k®�k��� � �t£ ¨ ¯ ¨ §i� ô ñgù2ð � � ÷¥À � � øq¼

ù6¼ ËC9QÌÎÍO?@Ͻ?@5O36-0ÐdÌ �/�7x/«��Õi3¶9<3_Õ�Ì2þ/¡9</��o�&;O9.²J³�´_µY·C¸�/�5Õi3¶9<3_Õ�Ì �/¡9<ÐY��ÌÎÐ��Ä;L/×5L?@5Ö54;O-0-0/

��� ¨ ½�k¬���© � � ¤¥± � � Á�¨g¢ © ¨g�2  � � ±  �¦���k� ¢k®�k��� ��� »2±6©É­&� � ­&� ¢�� �.£��&¬'Ç0� � ­ ¿  ©ª� � ¬ � �U� µY²J³�´¶µq·�¸ � .�¸ � ®± . �&¬   ± � ­ ¨�¢�¨ ­  �®� ¢ �.± � ©  �¨ © ¢ ��æ¶Ê �� � ±õ­k� �¡ �¢ �� � � � ²J³�´¶µq·�¸ ¼��O�i±  Æ� ¤ ¨ ½� ¢v� ± �ß  �k£�­ ¨�¢�¨ ­  �®� ¢ ��k¬   ± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �£�©ª¬�¬���   © ¢�¢��� � ±6­   ©�¶£�� � � ²J³ ��µq·�¸ �   ¯ ¨�¢ ­k� � ¬ ��k»2±6� �¡ �Å ¬k¤¥©�£H�&¬  J� �w­&� �6� ±6­ ¿  �&± ¢ ô � � �� ¨ £�� ¢ ¬C¯°�i± ¢�  �i±   ­k� ¢ ¯6¬ ³ Ww¿ ¯ ¢ �«­ ¦ � � � · � � ¬ ¨ ©  ����&æ � © ¢�� �� µ�.�¸ »2±6©8�&¬   ± � ­ ¨�¢�¨ ­  �®� ¢ � � � ²J³ ��µY³É¸ »�±Ä¤[� � © � � �¡  ©ªæ_� ¢�¨.¨ ±�­&� �¡ �¢ � � � � ²J³�´¶µq³¹¸ ¼ ï © ? �k¬   ± � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � £�©ª¬�¬v��© ¢�¢��� � ±6­   ©ªÂ6£�� � � ²J³�´¶µq·�¸� � � © Á � ¨ ± W �  �� �o­ ¨�¢�¨ ­  �®� ¢ �w­k� �¡ �¢�¨ £ . ¨ £�� ¢ ¬ . �k¬  ' �¢ © Á © ¨ £�¬�± ¢ ô � � ���   ¯½�i± ¢�  ��±   ­k� ¢ ¯6¬ ³ Ww¿ ¯ ¢ ��­ ¦ � � � · £��ë­ ¨�¢�¨ ­  �®� ¢ �Æ­k� �2 �¢�¨ £ � � �� �� µ;?8¸ �k¬  �� �� µ�.�¸ ¼ ï © . �&¬   ± �o  �k£½­ ¨g¢�¨ ­  �®� ¢ � � � · � � � � © Á � ¨ ±.© � Ç �� ¢ ©ª�k± ¢ �i± ��&§ ¨ £ ®¨ W�   ¬v© 1 3 � µq²t³�´¶µq·�¸ �-���� ¸�Å@¨ £�� ¢ ¬É� �㨶Å_¨�Á �k­'£ª�k¬ � �  è¨g  ©�� � ¬ � �t£ ¨ ¯ ¢ ��¯4¼ ���ê

ý Í �/2?@9«þ/2�ÿ/ � ��� ���eb(� \$� `�� _ d\�T d\,]^\,_a`�\�TcT b )6`�b����e\ g(d\ f� T b7\,g 9S\�²J³�´¶µq·�¸\�` * µ�� � W׸ \�` W � � µ;� � W׸ ��V8_a`UX V8]�]^\ )6T � � ��ZI� ` ! Z[TWV8g;�AT % bc_a`ed\ f8ghZ[TW\kV8g��i,b�`GZ[TW\ 9S\ , sĵB1:¸ \$� `�X V8_'� `GZ _a`G\ d\ f[Z[TW\ >Z � µ^, sĵB1x¸ � �_¸ �2� g * µ;� � W׸ \�`_)uV� g`BV� `2X V8gS) ��TWVYX-Z[T@³ ����b \$� `�W � � µ;� � W׸5� )ag VYX�� \ 9S\�· ! T % bc_a`ed\ f8g Z[TW\�V8g i,b�`7Z[TW\ 9S\,��� � � ���� � s � µ �� � � �� µG1x¸�¸�\$� `�X V8_'� `7Z _a`G\�\�` d\ f[Z[TW\ >Z � µ�, s°µG1x¸ � �_¸��2� g �� � � �

� µ * µ�� � W׸�¸2#D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �º���ü¨üµ ¯ ¢ ��¯4¼ ��� ¼ �°¸ £ ¨C¢ �&£ ¨g  ©�� �� µ�, sĵB1:¸ � �_¸�# O q .ºµG��¸ � µB1 � �8�_¸H��uté � �¡ �¢ � � ¬C»2±6�+¯½�i± ¢�  ��±   � 3 � � �i±¶¬ ¨�Á � � ¬ * µG�o� � W׸�# � * µ;� � W׸ �  W � � µ7�8� � W׸!# W � � µ;� � W׸ ¼ �ë�$¢ �&¯ ¢ � �6� ± � ¯ ¨g¢ ± � £��k¬t�i �v�   ¬ ¨ ¬�¬���­k© ��k¬ ¨ ±����k¶±  *� �ã­k�  v  ��¬v�k­   ©�� � ®¨A� �   W �   »2±6©�¬v� ¢VÁ � �¡  ®¨ÿ����&æ � © ¢ * µ�� � W׸ �  W � � µ�� � W׸èÅ �   � � ­k�i��¯ ¨�¢ �t� � ¬v±6© Ág¨��¡  £ª�k¬ ����&æ � ©   ©�� � ¬�¯ ¨ ¬ ®¨ ¯ ¨ ¬ �_� �ü¨ ê¿�· !SE�#ë· E<Å

Page 16: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �¿ Q µG�o�@¸(# Q µ��_¸èÅ¿���µG�o�@¸(# ��µ��_¸èÅ¿ ���@µ7�8�_¸ #&���@µ;�_¸�Å¿ £ ¨�Ág¨ £ª± ¨g  ©ª� � ��� �k¬   £ ¨ ����k��� Å¿ ��iµG�o�@¸$#� � �� � � ! � µ;�_¸�Å¿ O εG�o�@¸(# O ε��_¸ � ���@µG��¸�Å¿ O �kµG�o�@¸(# O �kµ��_¸ ­ ¨�¢����@µG�8�_¸(# ���@µ;�_¸ � ���@µG��¸�Å¿ �O �kµG�o�@¸(# �O �kµ��_¸èÅ¿ *�µG�o�@¸/# *'µ;�_¸ ­ ¨�¢ � J � !KE � µG�o�@¸/# � J � E � µ;�_¸.µ ����k���ã¬v© O ε7�8�_¸ .#O ε;�_¸�¸�Å¿ � µ7�8�_¸(# � µ��_¸èÅ¿ W � µ7�8� � W׸(#<W � µ�� � W׸èÅ¿ W � � µ7�8� � W׸(#<W � � µ;� � W׸ ¼Àx¨ Ç0� � ­   ©�� � ®¨ ¬�±¶¯6¯°� ¢v  ­k�i��¯ ¨ ­  �� ê � � #�· � . � �����æ � ©ª�t¯ ¨�¢

�OµG��¸(#9.ºµ7��¸ � µG1 � �8�_¸�k¬  C¨ £ª� ¢ ¬ � ¤ ¨ ¯ ¢k®�&¬�£��  �¦���k� ¢k®�k��� � � ¼ ¨ © �¡Ág¨�¢ © ¨��¡  ��¯ ¨�¢ £��w¬v�i±6¬ ¿ § ¢ �i±6¯½� µ ô �? � � � E � � � � ¸6M�� � � � � ��¼ ï �i©  �³ ± � ­k� ¢ ¯6¬ W � � µ�� � W׸q¿ ¯ ¢ ��­ ¦ � � � ·Å �   ¬��i©  (� �± �â��k£ ��k��� �¡  »2±6�&£�­&� � »2±6� �_¨g� ¬ �� � � �

� µ * µ�� � W׸�¸ ¼ � �+¨ ¯6¯6£�©ª»2± ¨��¡  £ª�  �¦¹��k� ¢k®�k���� � ¼[ Š� �ü �¢ �i± Á �Æ»2±6�J£ ¨ Ç0� � ­   ©�� ��� � ê � #�³ �_. � �¹��&æ � ©��Ư ¨�¢� � µ7� � ¸(# �� � � �

� µ�.�¸èµG� � ¸ � µ �� � � �� µB1:¸ � � � � � ¸¨ £ ¨ ����k����© �¡ «��k§ ¢�¨ £��J¬�± ¢!� »2±6� � ¬�± ¢!� �õ­ ¨�¢ £��&¬ � �k±«Ê�© �¡ «��&§ ¢�¨ £ª�k¬�¬v� �¡ � �k¬�¬v�i�o���k¬Éæ � ©��&¬ � �   � ¢ �o�&¬ ��&§ ¨ ±«Ê � �k±«Ê ®¨C� �&±«Ê°¼ î ���o���

O q � �� � � �� µ�.�¸èµG� � ¸ � µ �� � � �

� µB1:¸ � � � � � ¸H�� � # � µ�,��� � � ���� � s � µ �� � � �� µB1:¸�¸ � � � ¸

� �* �¢ �i± Á �tÂ6©ª� � � µ�, sĵB1x¸ � �_¸�# � µ�,��� � � �� � � s � µ �� � � �� µB1x¸v¸ � � � ¸ t

ï �i©  $? ± � � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� �C� �É­ ¨�¢�¢���É© �¡ «��k§ ¢�¨ Â6£�� � � ²t³�´_µY·C¸4� �É­ ¨g¢�¨ ­  �®� ¢ �­k� �2 �¢�¨ £ µ ± � ©  è¨ © ¢ � ¸$. �  º� � � © Á � ¨ ± W ¼F(/2�$�ÿ/ � � � �^Z�� �eb�³ \$� `���_kX V8gS) �GW�� )ag VYX�� \ 9S\ë· !2Z[TWV8g;� �� �� µ;?8¸!\$� `� _ \�g-\8)ag(d\$��\,_a`7Z[`;b7V8_C9S\�X-Z g g(d\!bc_a`ed\ f8g ZSi�TW\09S\�²t³�´¶µq³¹¸2#i"��� V8b�`�1 J ��_ ) ��\*�'9SVYX VY\�� X,b7\,_a`G9S\�? #�� V8b�`$� 3 � µq²t³�´6µY·C¸v¸�`G\�T ���e\, s°µ"�ĸ�#m1 J # � V8b�`�W � 3 � `G\�T ��� % V8_ Z b�` � 3 � µq²t³�´¶µq·�¸ �-� � �

� ¸2# �@TWV8g;�W � � W \�`5!(� b:³l\$� `(��_5X V8gS) � W � �Óô � )ag VYX�� \09S\È· !(Z[TWV8g;��, �� ���� � s � µ �� �� µ"�ĸv¸\$� ` ��_ ) ��\*�R9SVYX VY\�� X,b7\,_a`�9S\ �� �� µ;?8¸2#

Page 17: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �

D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 � ¨�¸ ï �i©   � ± � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� �Bµ © ¢v¢��� � ±6­   ©�Â6£ª�w�  �� �� © Á � ¨ ± W׸ ¬v�  �¢ �i± Ág¨��¡ ��6¨�� ¬�£Y¤[©ª� ¨ §i�ë¯ ¨�¢ �� �� � �J£ ¨ ­k£ ¨ ¬�¬�� � ¤ ��k»2±6© Ág¨ £ª� � ­&�� � ? ¼ ®� £ ¨ ¬��&­   ©ª� � ¯ ¢���&­ �� � � �¡  �õ� ��¨ÓÁ ±�­k�i���o� �¡  � � ­&� � ¬  �¢ ±6©  �� ®¨¯ ¨�¢V  © ¢È� � ? ¼ ��� �&�o¯6£ª�i©��t£��&¬�����k���k¬ � �  è¨<  ©�� � ¬k¼ ����¨ ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o�� ¤¥�k¬�¯ ¨ ­k�&¬ Á �k­   � ¢ ©ª�k£ª¬ 1 ê * ' ��J * ' ��

�t

À ¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� 1 © �6� ±6©   ± � ©�¬����o� ¢ ¯ ¦ ©ª¬������ �¡ �¢ �t£��k¬ � ± ¨ ±«Êßê1 � ê * � ' ��J * � ' ���

tï �i©ª� �¡  �^3 * ' ��J B D ñ F �   � � 3 * � ' ��J B D ñ F ¼ î � � ¬�© �¹�� ¢ � � ¬É£ª��­k���&ú�­&©�� �¡ �� � ?� Jê ²t³�´6µY·C¸/. �����&æ � ©:¯ ¨�¢ � 4. � � � ?Hµ��@¸èµ �6¸ � tî ¤[�&¬   ± � ­k���&ú�­k©ª� �¡ º� � �+� ±6£q¼< ��± ¢�  �i±  �� 3�²J³�´¶µq·�¸èÅ ¯½�i± ¢�  �i±  2� � 3 � �� � � �� Å � �ü¨?Hµ;� � ¸ # � 6 � µ � �� � � �� ¸ � ?Hµ8�S' �� Eh' �� ¸-tÀx¨×¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� �=? ��  �¨��¡ C� �.­ ¨�¢�¢���.© �¡ «��&§ ¢�¨ Â6£�� Å � � � � à �k¬  � �¢ © Á © ¨ £H¬v± ¢4��   © �¡ «��&§ ¢�¨ Â6£��Ƭ�± ¢�²t³�´_µq·�¸:��� ¼���Ê«¯ ¢ ©ª�o� � ¬º­&�  v  �'¯ ¢ �i¯ ¢ © ��  «�� ®¨ ¯ ¨g¢v  © ¢�� �'£ ¨����k­&�i��¯°�i¬v©   ©�� �

²t³�´6µY·C¸(# �� ) � � �� ���� ��� ) � � � � � �

� �� �� *

�! � � ��

� � ��   ± � © ¨��¡  £Y¤ ¨ ­   ©ª� � ¯ ¨�¢ ��±6£   ©�¯¶£�©�­ ¨g  ©ª� �×� � � £ ®¨Q¿á� �&¬�¬�±¶¬k¼ �È�   � � ¬ � � £ª�¬��i±¶¬ ¿ � � ¬��&��Â6£ª� � � � �*Ç0� ¢ � �� � ��� ¨g �¢ ©�­k�&¬ *n#n " � �°µ;? ���� � ? ���� � t tWt ? ���� ¸O  �k£ª£��&¬»2±6� � �@# ñ«¼ < �i± ¢�  �i±   ��� ¨g �¢ ©�­&� * 3 � � � �   � � ¬ � � µ�*Ƹ £Y¤[� � ¬��&��Â6£�� � �� ¨< �¢ ©ª­k�&¬É�i   � � ±6�k¬ ®¨ ¯ ¨�¢v  © ¢�� � * ¯ ¨g¢ �'±6£   ©�¯6£ª©�­ ¨<  ©�� �w¨�Á �&­J± � �Ư6±6©�¬v¬ ¨�� ­k�� � ? ��¼ î ¤¥�k¬   ± � ¬��i±¶¬ ¿ � � ¬��&��Â6£ª� � � � �8¼ �ë�ã¨� � # �� ) � J� � � µ#*t¸-t

é � �¡ �¢ � � ¬:»2±6� Å ¯½�i± ¢4  �i±  !* 3 � � Å £Y¤[� � ¬��&��Â6£ª��� � ) ��� � � � � � �� � ��� ) � � � � � � ���� �� *

�! � ����

�k¬   ¬  �¨ Â6£��¹¬��i±6¬�£Y¤ ¨ ­   ©ª� ��� � � ¯ ¨�¢ ��±¶£   ©ª¯6£�©ª­ ¨g  ©�� � �  ���   ± � ©�� � ¬�­k�  �  � ¨ ­   ©�� � ¼� � � �¡  ©ªæ_� � ¬ �â¨�Á �&­ · � ¼ ��£ª� ¢ ¬ Å ¬v© � �k¬   ± �ÿ��&£ ��k��� �¡ L� � �JÅ[� ¬k¤ ��k­ ¢ ©  �� ��Ç ¨��­&� �± � ©ª»�±¶� ��#9?

� � � ®± � �&¬   ± �>��&£ ��&�o� �2 ¹� � � �� ¼ � ¤ ¨ ±  �¢ ��¯ ¨�¢v kÅ � �+¨ ± � ©ª¬�� ¿�o� ¢ ¯ ¦ ©ª¬����� �� �¶µ ô � � � �� ¸ µ �� �7� �� ¸ � t

��� ¯°�&±  O¨ © � ¬�© ����k­k���o¯½�i¬�� ¢ £q¤ ¨ ­   ©�� ��� � � ¬�± ¢ � � )���� � � � � � ���� ��� ) � � � �� � � �� �� *

�! � � ��

¯6±6©ª¬�»2±6�ê

Page 18: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �

¿ ¬v© � # ? � Å4¨ £ª� ¢ ¬ � ���� �

� *�! � ���� # ���� �

� * � �! � ���� � ®± * � # �7* 3� � µ#*t¸èÅ �   ± � �º¬v©���¯6£�� Á��� ¢ ©ªæ6­ ¨g  ©�� � ��� �¡ �¢ ��»2±4¤¥� �.¨Æ�_¨�� ¬�­&�º­ ¨ ¬

�ý � � � � � #�

ý � � � � � �¿ ¬�© � 3 � �� Å@¨ £�� ¢ ¬�ê¿ ¬�© � 3 ô � � � �� Å � �+¨ � � �� �

� *�! � � �� # � �� �

� *�! � � �� Å« �¨��6� ©ª¬

»2±6� ¿ ¬�© � �3 ô � � � �� Å�� � �� �� *

�! � � �� # � �� �

� � * �! � � � �� Å � ®± µ �� � � �!�� ¸

�k¬   ± � ��k£ ��k��� �¡ �� ��ý � � � � � � ©21 �� ¢ � �¡ ë� � µ ���� �! ¸ �   »2±6© � � ����k¯½� �¶� »�±¶� � �

£ ¨ ­&£ ¨ ¬v¬�� � � � ��� � ±6£�� ô � � � �� ¼� © �_¨ £��&�o� �¡ �Ź� © ¢ �ü»2±6� � � J � à �k¬   © �¡ «��k§ ¢�¨ Â6£��+¬v± ¢.²t³�´6µY·C¸N� ��¢ � Á ©�� �2 Ú®¨� © ¢ �ë»2±6�Æ£ ¨ ¬��i�����%� )�� J� � %� ���� ��� ) � � � � � �

� � � M ½µ�µ �� �7� �� ¸ � ¸ � �� 6�� µ � �� �

� *�! � � �� � ��_¸ � � 6 � µ ô � � � �� � ���¸ � � � � J µ �� * �

! � ¸�� Ã���k¬   ­k� �¡Á � ¢ §i� �¡  � Å ­�¼ ¿k®¨<¿X� ¼ Å � �ë  � �6¨��¡  ­&�i��¯   � � � � 6 � µ ô � � � �� � ���¸ � � M ½µvµ �� � � �� ¸ � ¸(#� 6�� µ � �� � ���¸$# ô Å »�±¶�J£ ¨ ¬��i���o�%� )�� J� � %

� ���� �� � ) � � � �� �� 6 � µ � �� �

� *�! � � �� � ��@¸�� � J µ �� * �

! � ¸�� à �µ ô ¸

�k¬   ­k� �¡Á � ¢ §�� �¡  �g¼ é ¨ © �¡  � �_¨��¡ kÅ�18µ �6¸ �k¬   ± � ��k£ ��k��� �¡ �� � * ' ��� B D ñ F �   1 � µ � � ¸

�k¬   ± �B��&£ ��k��� �¡ �� �+* � ' ��� B D ñ F2Å6� � � ­t£Y¤ ¨ ¯6¯6£�©ª­ ¨g  ©�� ��

� ê ²t³�´6µY³¹¸1. �����&æ � ©��Ư ¨�¢ � 4. 18µ � � ¸ � ��µ��_¸ÒµB1Lµ �6¸�¸ ��k¬   ± � ­&�«��úo­&©�� �2 È� � � ¼< ��± ¢�  �i±  �� 3�²J³�´¶µq³¹¸èÅ ¯½�i± ¢É  �i±  �� � 3 � � � � � ��k§ ¨ £ ®¨

��µ;� � ¸ # � 6 � µ � � � � � ¸ � ��µ8�S' �� Eh' �� ¸-t� � � ­ �

� �&¬  ü� ��­ ¨�¢�¢����© �¡ «��&§ ¢�¨ ¶£������ � ±6£�� £ª��­k� �¡ �¢ �߬v± ¢+²J³�´6µq³¹¸ ¬�©��  ¬��&±6£��&�o� �2  ¬v©:£ ¨ ¬����o���%� )�� J� � %������ �� � ) � � � �� �

� 6 � µ � � �� � � µ�*Ƹ

�! � � � � ��@¸�� � � µ

�� � � µ�*Ƹ

�! � ¸�� à �

�k¬   ­k� �¡Á � ¢ §�� �¡  � Å � ®±w� �+¨J  � � ±*­k���o¯   � � ±.Ç ¨ ©   »�±¶� � �� ¢��� ¨ £�©ª¬��ȱ � ��Â6© �v�k­ ¿  ©ª� �*� � � � ¬�± ¢ � ¼ é ¨ ©ª¬É­k�  �  �t¬v�i���o��­&� ¢�¢ �k¬v¯°� �¶�ü  � ¢ ���믽�i± ¢É  � ¢ ��� ®¨£ ¨ ¬v�i�o��� µ ���«¸ ¯6±¶©�¬�»2±6�¿ £��k¬ Á ��£�±6���k¬ � �k¬�¬��i±6¬ ¿ � � ¬��&��Â6£��&¬ � � ²J³�´¶µq·�¸ �  �²t³�´¶µq³¹¸ »�±¶©°¬v��­k� ¢v¢ � ¿¬�¯½� �6� � �¡  ¬v� �¡ ü��&§ ¨ ±«Ê*¯°�i± ¢ £��k¬����k¬v± ¢ �&¬�æ«Ê ��&�k¬È¬�± ¢º²t³�´¶µq·�¸ �  º²t³�´6µY³É¸�Å

Page 19: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �¿ ¯ ¨�¢ ­&� � ¬  �¢ ±6­   ©ª� �+� �Æ£q¤¥©�¬����o� ¢ ¯ ¦ ©ª¬���� 1LÅ ¯½�i± ¢É  �i±   �/3 * ' ��J � �ü¨1Lµ;?Hµ8��' �� Eh' �� ¸èµ �6¸�¸$# ��µ"�S' �� Eh' �� ¸ÒµG18µ �6¸�¸-t��� Á ©ª� �¡ ü� �ß�o� �¡ �¢ � ¢ »2±4¤¥± � ­&�«��ú�­k©�� �¡ ã� � ��� ±6£ � � � �k¬  ×� �Ú­ ¨�¢�¢���© �¡ «��&§ ¢�¨ Â6£���¬v± ¢È²J³�´6µq³¹¸:� � ¼ � � � ­ � �k¬  �� �Æ­ ¨�¢�¢���t© �¡ «��k§ ¢�¨ Â6£ª��¼Â ¸ �� Á © � �&�o��� �¡ �W � � W�Å ¯6±6©�¬v»2±6� LNM ?Hµ"�°¸�# LNM ?�µB1 J ¸ .# ñ¶¼ é � �¡ �¢ � � ¬»2±6� , �� �� � � s � µ �� �� µ��°¸�¸°ÁH�� ¢ ©ìæ_�H£ ¨������æ � ©   ©�� �t� ¤¥± � ¯¶¬��k± � �«­&�«��ú�­k©�� �¡ �� � �� �� µ;?L¸ê � ¤¥± � �t¯ ¨�¢v LNM �� �� µ;?8¸èµ^, �� ���� � s � µ �� �� µ"�ĸv¸�¸$# LNM �� �� µ�?8¸Òµ �� �� µ��°¸�¸(# LNM ?Hµ"�°¸ # LNM ?�µB1 J ¸(# ô �� ¤ ¨ ±  �¢ �.¯ ¨�¢V �Å ¬�© � ���k¬   ± � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � © ¢v¢��� � ±6­   ©�Â6£ª�w�&¬�¬�� �¡  ©��&£�£ª�k��� �¡   �&�o¯ �� ¢���&� � � ²J³�´6µq³¹¸(� �ë­ ¨g¢�¨ ­  �®� ¢ �ë­k� �2 �¢�¨ £ �� �� µ�.�¸ � ¨ ©�¬ � � �Ö��k»2±6© Ág¨ £�� �2  �®¨ �� �� µ;?L¸èÅ¡¨ £ª� ¢ ¬L�i±CÂ6©ª� � � �2�&¬  �� � � © Á � ¨ ±¬�±6¯ �� ¢ ©ª�k± ¢ ¬  �¢ ©�­   �k��� �¡ �®¨@W � ¨ £�� ¢ ¬»2±6� �� �� µ��°¸ �k¬   © �¡Á�¨g¢ © ¨g�2  �ë¯ ¨�¢ ��� �

�   � �ü¨C� �Æ­k�ÆÇ ¨ ©  LNM � � µ �� �� µ��°¸�¸(# ñ Z�i±CÂ6©ª� � £�� � © Á � ¨ ± � � � � �&¬   © � Ç �� ¢ ©ª�k± ¢ �i± ��k§ ¨ £ ®¨7W � ¼ �º£�� ¢ ¬ � � »2±6©_�&¬   �&¬�¬�� �«¿  ©ª�k£�£ª�k��� �¡ ½  �k��¯ �� ¢���k�H© ¢�¢��� � ±6­   ©�¶£��8�&¬   � � ¯ ¨g¢v  ©ª­k±6£ª©�� ¢ § �� ���� ¢ ©�»2±6�H© ¢v¢��� � ±6­   ©�Â6£ª�µ�÷ �Ä�&ø ÅΠ�¦ ¼��¶¼� ¸èÅÎ� � � ­H©�� ¨ §i�8¯ ¨�¢ �� �� � ¤¥± � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � § �� ���� ¢ ©ª»�±¶�(© ¢�¢��� � ±6­   ©ªÂ6£��� � � ²J³�´_µY·C¸èµ ¯ ¢ �i¯4¼ � �«¸èÅÄ� �'­ ¨g¢�¨ ­  �®� ¢ ��­k� �¡ �¢�¨ £ .ÈÅ � ¨ ©ª¬ � � ����k»2±6© Ág¨ £�� �2  �®¨ ?�Å �   � �㨠LNM � � µ �� �� µ"�°¸�¸(# LNM ��µ��°¸$# LNM ��µB1 J ¸-té ¨ ©ª¬ �8Å���  è¨��¡  § �� �¹�� ¢ ©�»2±6� Å �k¬   ��±oÂ6©ª� � ± � � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � �&¬�¬�� �¡  ©��&£�£ª�k��� �¡ � �.­ ¨�¢�¢���*© �¡ «��&§ ¢�¨ ¶£�� Å �i±õÂ6©�� � ± � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � © �¶� ±6©   � ®¨ ¯ ¨�¢V  © ¢'� ¤¥± �¬��i±¶¬ ¿ § ¢ �i±6¯½�*¯ ¨�¢�¨ ½�i£�©ª»�±¶�.¯ ¢ ��¯ ¢ � µ�÷ �Ä��ø ÅH �¦ ¼��¶¼� ¸ ¼ ��� ¨��_¨g� ¬£��.¯ ¢ �k��©�� ¢­ ¨ ¬ LNM ��µB1 J ¸ # ñ¯ ¨�¢ £ ¨�����&æ � ©   ©ª� �+� ¤[± � ¯6¬v�k± � ��­k���&ú�­&©�� �¡ �� � ? �   � � ­k� ¢ �LNM ��µB1 J ¸$# ñ �_¨�� ¬È£ª� � �k±�ʶ© ®�k���Æ­ ¨ ¬�¯ ¨�¢ £ª�  �¦���&� ¢k®�&�o� ��� ¼¥Â4¼é � �¡ �¢ � � ¬È� ¨ © �¡  � �_¨��¡  »2±6� ²J³�´¶µq·�¸�¨ £ ¨ ¯ ¢ ��¯ ¢ © ��  «�� � êý Í �/2?@9«þ/2�ÿ/ ��� � ���% bc_a`ed\ f8ghZ[TW\�V8g�i,b�`7Z[TW\ 9S\�1 J 4�d\,g b�� \ A� b � � µB1 J � �@¸$# ñ � bK�A\$� `1��\,]�b:� bc]@)6TW\�g d\ f�uT b7\,g�_ V8_A\�TcT b )6`�b�����\$!� bcb � � µB1 J � �@¸$# IKJ µ��@¸�� bK�A\$� `*\�TcT b )6`;b�����\�g d\ f� T b7\,g�#D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �tµ © ¸ î ¤¥�k¬   £��믽�i© �2  ­ ¸(� ±  �¦���&� ¢k®�&�o� � � ¼µ ©ª© ¸ î � � ¬v© ���� ¢ � � ¬8± � �ÉÇ0� � ­   ©ª� ��� 3 � µq²t³�´6µY·C¸v¸4  �&£�£ª�¹»2±4¤¥� �¨ ©  /, sĵ"�ĸ(#1 J«¼ ï ±6¯6¯½�i¬�� � ¬w»2±6� � 3 � µq²t³�´¶µq·�¸ �-� � �

� ¸ ¼ ï �i©  ^� ± �å��k£ ��k��� �¡  �&£�£ª©�¯ ¿  ©ª»�±¶� ¢���k§i±6£ª©�� ¢ ¼ ï �i©  � ± �ãÁ �i©ª¬�© �6¨ §i� � � � ¬v± ¢ £ª�k»2±6�k£IKJw�&¬   ­&� � ¬  è¨��¡  �  

Page 20: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �¬��i©  �W ± � � �¡  ©ª� ¢ ¬�±«úo¬ ¨ ���o� �2  § ¢�¨��6� ¯°�i± ¢ »2±4¤¥� �ÿ¨ ©   * µ;� � W׸ \ �  »2±6�*£��*£ª�k���o�o¯ ¢���&­ �� � � �¡  ¬v�i©  'ÁH�� ¢ ©ìæ �� µ ©Y¼[�g¼ÿ¬�© ³ �k¬   ± � ­&� ¢ ¯¶¬�£ª�«­ ¨ £ � � �¨�¢ ­ ¦ ©�� �� � ©ª� �ß� �w­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � ±¶£�£�� Ww¿ ¯ ¢ ��­ ¦ � � � ·ÅL¨ £�� ¢ ¬ �� �� µ;?8¸ �k¬  ± � � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � �k¬v¬�� �¡  ©��k£ª£��&�o� �2 w� �×­ ¨�¢�¢���ש �2 «��k§ ¢�¨ Â6£ª� � � ²J³�´¶µq³¹¸ �  , �� ���� � s � µ �� �� µ��°¸v¸ �&¬   ± � ¯6¬v�k± � ��­k���&ú�­&©�� �¡ �� � �� �� µ�?8¸�¸ ¼ ï �i©  �³ ± � ­k� ¢ ¯6¬ � �­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±¶£�£�� Å W � � µ;� � W׸Y¿ ¯ ¢ �«­ ¦ � � � · ¼ ���*¨'�6¨�� ¬É­&�  �  ��¬�©   ± ¨<  ©�� �ê ô ¸ IKJ�k¬   ­k� � ¬  è¨��¡  ¬�± ¢ * µ�� � W׸��k§ ¨ £ ®¨ IjJ µ;�_¸�Å ­ ¨�¢ * µ;� � W׸ \ "Åð ¸ � µ^, sĵ"�ĸ ��� ¸ �&¬   ­&� � ¬  �¨��¡  �Ƭ�± ¢ * µ;� � W׸���&§ ¨ £ª� ®¨ � µ^, s4µ"�°¸ � �_¸�µ0 �¦ ¼ � �«¸

�  ��¸ � µ^, �� � � �� � � s � µ �� � � �

� µ��°¸�¸ ��� ¸ �&¬   ­&� � ¬  �¨��¡  �õ¬v± ¢ �� � � �� µ * µ�� � W׸�¸Ö��&§ ¨ £�� ®¨� µ^, s°µ��°¸ � �_¸ºµ0 �¦ ¼ � �«¸ ¼��¢kÅ�, s°µ"�°¸0# 1 J¶¼ À �C­&� ¢ ¯6¬ ³���  è¨��¡ t� �­ ¨g¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±6£ª£�� Åx²J³�´¶µq³¹¸¨ £ ¨ ¯ ¢ �i¯ ¢ © ��  «�� � ¼ � ±�£��k����� ��� ¼¥Â�� � � �ß���� � ±6©  ë¨ £�� ¢ ¬�»2±6�*ê�I �� � � ���� � J � �k¬  

­k� � ¬  è¨g�2  ¬�± ¢ �� � � �� µ * µ;� � W׸�¸���k§ ¨ £ ®¨ � µ�,��� � � ���� � s � µ �� � � �

� µ��°¸v¸ � �_¸ ¼ � © �_¨ £��&�o� �¡ �Å � �¨ ¯6¯6£ª©�»2± ¨��¡  £ª�믰��© �¡  ��¸ ­k© ¿á� �&¬�¬v±6¬ Å � �+ �¢ �i± Á �ù ¸ I �� � � �� � � J � �k¬   ­k� � ¬  è¨��¡  ¬�± ¢ �� � � �

� µ * µ;� � W׸�¸C��&§ ¨ £ ®¨ � µB1 J � �@¸ ¼� �ã� �  è¨��¡ G, £ ¨ Ç0� � ­   ©�� � ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � �+* µ;� � W׸�Ŷ� � ô ¸ � �ü¨LNM ?�µ^,¶¸$# � 6 � µ * µ;� � W׸v¸ IKJ µ;�_¸ t

� ¤ ¨ ±  �¢ ��¯ ¨�¢v  �� � � �� µ�,¶¸ �&¬   Â6©�� �$����&æ � ©ª�o�   �&¬   £ ¨ Ç0� � ­   ©�� � ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6�� � �� � � �

� µ * µ�� � W׸�¸Èµ ¯ ¨�¢É����&æ � ©   ©ª� � ����&�o� � �ë­k�  �  � � � ¢�� © ®� ¢ � ¸ �  È¨ £�� ¢ ¬ � �ëù ¸� � � �ü���� � ±6©   »2±6�LNM µ �� � � �� µ;?L¸�¸Òµ �� � � �

� µ^,¶¸�¸(# � 6 � µ �� � � �� µ * µ�� � W׸�¸�¸ � µB1 J � �_¸ht

î �i���o��� �ר� 6 � µ �� � � �

� µ * µ;� � W׸v¸�¸$# � 6 � µ * µ�� � W׸�¸�   »2±4¤¥� � ¬ ¨ ©   »�±¶�

LNM µ �� � � �� µ�?8¸�¸èµ �� � � �

� µ^,¶¸�¸(# LNM ?Hµ�,6¸ Z� �* �¢ �i± Á �tÂ6©ª� � IKJ µ��@¸$# � µB1 J � �_¸ t� � � ­ ²t³�´6µY·C¸@¨ £ ¨ ¯ ¢ �i¯ ¢ © ��  «�� � ¼ î �i�o����¬v± ¢x²J³�´¶µq·�¸ ©�£ àë¨ © �¡ «��k§ ¢�¨ Â6©�£ª©  «��£���­ ¨ £ª� � ±o­ ¨�¢�¨ ­  �®� ¢ � � �   ��±   � ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � £ª©�¬�¬v��© ¢v¢��� � ±6­   ©�Â6£ª� µ�÷ À ��ð<ø ¸èÅ � �� �ü���� � ±6©   ¯ ¨g¢ £ ¨ ¯ ¢ ��¯°�i¬v©   ©�� � ��� £��

Page 21: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �ý Í �/2?@9«þ/2�ÿ/ �� � ���èËC9QÌÎÍL?@Ï@?@5L3¶-bÐdÌ �/t7x/��ÉÕi3¶9<3_Õ�Ì2þ/¡9</���ØH?@;O9�²J³�´�� ��% \,_'��\,]^i�TW\9S\$� �,V8_ X�`�b7V8_'� X-Z ghZSX�`+>\,g \$� Z�;��VYX,bud\Y\$� ZI� �X�T Z�;��\$� 9&%-d\V����b54oZ[TW\,_ X \ 9S\$� g \8)ag d\$��\,_a`GZ[`�b7V8_'�9S\5X-Z g g(d\ bc_a`ed\ f8ghZSi�TW\[9S\*²J³�´6µq·�¸ 9S\AX-Z ghZSX�`+>\,g-\ X \,_a`�ghZ[T . � �d\ �,V8g ]^\ � _� � � `+>\,]^\�V8g,`�� V8_ V8g ] Z[T )uV� g�T % \$�S) ZSX \_)ag d\���b�TWi \,g `;b7\,_�³ à µq²t³�´6µY·C¸G� � . � � � � �¸$#

ó«¼�������� ������ �����ï �i©ª� �¡ ü· ± � ­k� ¢ ¯6¬*£ª�«­ ¨ £ � � � ¨�¢ ­ ¦ ©�� �� � ©�� �>� �Ú­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6��»2±6�k£ ¿­k� � »�±¶���   � ± � � ¨ £ª§ ®�k ¢ � ®¨o� © Á ©�¬v©�� � ­k� �¡ �¢�¨ £�� � � � ©���� � ¬v©�� � æ � ©ª�'¬�± ¢ë· ¼ï �i©   � � £���§ ¢ �i±6¯½� � �k¬ ��k£ ��k��� �¡  ¬H© �¡Á � ¢ ¬v©�Â6£ª�k¬ � � � ¼ ÀO¨ë� ©ª�o� � ¬�©ª� �� � � � � è¨��¡  »2±4¤¥�k¬�¯ ¨ ­k� Á �k­   � ¢ ©��k£x¬v± ¢�· �&¬   ± � ­ ¨�¢�¢��� #°Ã ¼ ��� ¯°�i¬v� ² #ݲt³�´_µq·�¸ ¼��� æ¶Ê«� � �k¬8�o�&¬�± ¢ �k¬ � �2 ¨i¨�¢ ¬�± ¢�² �   ��� ¼ ï © � �k¬   ± �ÿ��k£ ��k��� �¡ �� � ² �  (� �± �ÿ��k£ ��k��� �¡ �� � � � � �õ��k­ ¢ ©  ���� � � ¬�© � �  (� � ¬�� �2 H¢���k§i±¶£�©�� ¢ ¬L�   � �¡  £ª�¹����k���¯°��£ à�� ��i���­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©�»2±6��¼ ��� � ©  J¨ £�� ¢ ¬J»2±6� � �  !� � ¬v�.­k� ¢v¢ �&¬�¯½� �6� � �2  ¼î ��¨.¢ � Á ©ª� �¡ .®¨.� © ¢ ��»2±6� � �k¬   �k£�£ª©�¯   ©�»2±6� ¢���&§i±6£�©ª� ¢ �  t¨ £��'����&�o��¯½�i£ à«� ��i�o�­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6��»�±¶� � �ª¼ �ᣫ��Ê«©�¬   � � �&¬�©�¬v�i��� ¢ ¯ ¦ ©�¬����k¬O­ ¨g� � � ©ª»�±¶�k¬ � E · ��  ������ · � �  º� � � ­'± � ©�¬����o� ¢ ¯ ¦ ©ª¬����ë­ ¨�� � � ©�»2±6� � E ����� ¼ ���×� �   �­k�&¬ � �k±«ÊÚ§ ¢ �i±6¯½�k¬t© �6� ©�¬   © � ­   �&�o� �2 �� ¼ �ë� æ¶Ê«��± � ��o�&¬�± ¢ � � � ¨i¨�¢���¬�± ¢2� ¼ ï ± ¢¹  �i±  �  � ¢ ��� ¨ ʶ©ª� ¨ £½�&£�£ª©�¯   ©�»2±6�?� � � ² �i± � � ��� � � ­&� � ¬�© �4®� ¢ �£ ¨ �o�&¬�± ¢ � � �� ¨i¨g¢0 L   �&£�£ª�t»2±6� � � � ¨ ©  �Á ��£�±6��� ô ¯°��± ¢ £ ¨ ���k¬v± ¢ �J»�±¶� ¿  ©ª� �¡  �L #n L �8�� ¼ ï ± ¢ £ª�k¬   � ¢ �k¬ � � � �&£�£�©ª¯   ©ª»2±6�k¬ � � ² � � æ¶Ê«� � �k¬��o�&¬�± ¢ �k¬� �! ¨i¨g¢ »�±¶�k£�­&� � »2±6�&¬k¼ï �i©  *. ± � ­ ¨�¢�¨ ­  �®� ¢ �ë± � ©  �¨ © ¢ � � � � ¼��ᣠà*¨ ± � ©�¬v�i��� ¢ ¯ ¦ ©�¬���� � ¤[�&¬�¯ ¨ ­&�k¬Á �&­   � ¢ ©��&£�¬ëê

" ê ³ µY²�� � .�¸ ³ µ � �� � .�¸����&æ � ©:¯ ¨�¢

"�µG1x¸Òµ�� � ¸(#&1Lµ;�_¸ ¬v© ��� � �¯°��± ¢¹  ��±  0153�³ µY²�� � .�¸ ¼ é ¨ © �2  � �_¨g�2 kÅ ¬�© ��� � � Å_¨ £�� ¢ ¬É©ª£ à+¨ ± � ± � ©ª»2±6�©�¬v�i�o� ¢ ¯ ¦ ©ª¬���� � � ·ë¿á¨ £�§ ®�k ¢ �k¬ µ »2±6© �_¨g� ¬.­k��­ ¨ ¬.¯ ¢���k­&©�¬.¬v� �¡ +� �k¬*­&� ¢ ¯6¬ ¸·w÷ � ø ·w÷ � �[ø Å »2±6©�� �¡Á �i©ª� � ¬v± ¢/� � ¼ ����¨ � � � ­�± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� � �§ ¢ ��±6¯°�&¬'��±¶£   ©ª¯6£�©ª­ ¨g  ©ªÇ0¬ ·o÷ � ø � ·w÷ � �lø � ¼ é ¨ ©�¬ ·w÷ � ø � � ¤[�&¬  ¨ ±  �¢ �w»2±6�.£ª�§ ¢ ��±6¯°� � �k¬¯½�i© �¡  ¬ � ±   � ¢ �*� ¨ Ê«©�� ¨ £(�k£ª£�©�¯   ©�»2±6� �'µ;�_¸ »2±6©�­&� �¡  ©ª� �¡ �� �  ·w÷ � �[ø � � ¤[�&¬  �¨ ±  �¢ ��»2±6�È£��ɧ ¢ �i±6¯½� � �&¬�¯½�i© �¡  ¬ � ¤¥± ��  � ¢ ��� ¨ Ê«©�� ¨ £��k£ª£�©�¯   ©�»2±6��'µ;� � ¸ »2±6©�­&� �¡  ©�� �¡ �� � ¼ �O�i±   �&¬ë­k�&¬ë­k� � ¬v© ���� ¢�¨g  ©�� � ¬�©���¯6£�©ª»2±6� �¡  »�±¶� Å ¬�©L� �­ ¦ �i©ª¬�©   ± � � � ¬v�k��¶£�� � � ¢ �k¯ ¢���k¬�� �¡ è¨��¡  ¬ � �ë� �k¬ë­k£ ¨ ¬�¬v�k¬ � �C­&� � �v±6§ ¨ ©�¬�� ��� �  � ¢ �k¬�� ¨ Ê«©�� ¨ ±«Êü�&£�£ª©�¯   ©�»2±6�k¬ � � ² �   ± � � � ¬v�k��Â6£ª� � � ¢ �k¯ ¢���k¬�� �¡ è¨��¡  ¬ � � �� �k¬È­k£ ¨ ¬�¬v�k¬ � �t­k� � �v±¶§ ¨ ©�¬v� �+� �   � ¢ �k¬È� ¨ Ê«©ª� ¨ ±�Ê*�k£ª£�©ª¯   ©ª»�±¶�k¬ � � ��� Å ©ª£ àü¨± � �ÆÂ6© �v�k­   ©�� � ��ê � �_. � � �»2±6©:�k¬   ­ ¨�¢�¨ ­  «�� ¢ ©ª¬ ��k�Ư ¨g¢ � � µ � ¸ t

Page 22: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �ï �i©   � 3 � � ¼ �º�   � � ¬ � � ± � ©�¬v�i��� ¢ ¯ ¦ ©�¬���� � � � ¬v± ¢ � µ � ¸ ¼ ��  �¨��¡  ± ��o� ¢ ¯ ¦ ©ª¬���� � ��§ ¢ �i±¶¯°�&¬ Å � �  �¢�¨�� ¬vÇ0� ¢ ����£ ¨ �o�&¬�± ¢ � � � �"� � ± � ���o�&¬�± ¢ �� � ¨�¨�¢C� ��� µ � ¸èÅH� � � ­ü� � ± � �'±6£   ©�¯6£ª�w­k���o¯6£ª��Ê«� � �+£ ¨ ���k¬v± ¢ �+»2±4¤¥� �¨�Á�¨ ©   ­ ¦ �i©�¬v©¹¬�± ¢ � µ � ¸ ¼ é ¨ ©ª¬'£ ¨ã¢ �k¬  �¢ ©�­   ©�� �õ� �.£q¤ ¨ ¯6¯6£ª©�­ ¨g  ©ª� � � � ®¨5� �k¬  £q¤¥© � � �¡  ©  «�� Åx� � � ­ ÅLÁ ± £ª�­ ¦ �i©ìÊ � �&¬'���k¬v± ¢ �&¬'¬�± ¢ � �   � µ � ¸èÅ � � � �ÿ���� � ±6©  »2±6��� � ¯ ¢���&¬�� ¢VÁ �.£ ¨ �o�&¬�± ¢ ��¼��º£�� ¢ ¬t£ ¨*¢ �k¬  �¢ ©�­   ©�� �ß� ��£q¤¥©�¬v�i��� ¢ ¯ ¦ ©�¬���� "C®¨³ à µq²�� � .�¸ © �6� ±6©   ± � ©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� � ¤[�&¬�¯ ¨ ­&�k¬�¯ ¢��� ¦ ©�£�½� ¢V  ©ª� � ¬ � � ³ à µq²�� � .�¸¬�± ¢È³ à µ ���� � .�¸ ¼ � ¤[± � �ÆÇ ¨ �­k� � ¯6£ª±6¬���Ê«¯6£�©ª­k©   � Å � �㨠ê

� "�µG1x¸ � "�µ��°¸ � �-# � 1 � � � � `�1 Z � 3�³ à µY²�� � .�¸ tï © 1 3 � µq²�¸ �  /1 � 3 � µ ��� ¸ � �â� ©   »�±¶� 1 �  /1 � ��\ X V8g g \$�S)uV8_ 9S\,_a`¬�©º£��k± ¢ ¬.© �2 «��k§ ¢�¨ £��&¬w� ¢ Â6©  �¨ £��&¬o� �2  £ ¨ ����k��� Ág¨ £ª�k± ¢ ¬�± ¢.� �k¬ ��k£ ��k��� �¡  ¬ � �² �  C� � ��� »2±6©É¬v�*­k� ¢v¢ �&¬�¯½� �6� � �2  �   »2±6�+£��k¬'© �¡ «��&§ ¢�¨ £ª�k¬J� ¢ Â6©  è¨ £ª�k¬ � � 1¬�� �¡ �� ±6£ª£��k¬¹¬�± ¢ £ª�k¬ ��k£ ��k��� �¡  ¬�¬v�k��©�¬v©���¯6£��&¬ ¢���&§i±6£ª©�� ¢ ¬ � � � �&£�£ª©�¯   ©�»2±6�k¬ � � ² ¼��� ��k­ ¢ ©  '¨ £ª� ¢ ¬ 1 � 1 ��¼ ���ÿ� ©  '¨ ±6¬�¬v©¹»2±6� 1 ��\U`�ghZ _'� ��>\,g-\ �i± »2±6� 1 � ��\`;ghZ _'� � >\,g \ ¼ ï © . �&¬   ± � ­ ¨g¢�¨ ­  �®� ¢ � � � � £ ¨������æ � ©   ©�� � ¯6£�±¶¬ ¦_¨ ±  �Ág¨ ±  �¨ ±6¬�¬v©¯°��± ¢�1 3 � µq² � .�¸ �  @1 � 3 � µ ��� � .�¸ ¼���õ¢�¨ ¯¶¯°�&£�£��o»2±6� � à µY²C¸ �k¬   £Y¤[� � ¬��&��Â6£ª� � �k¬C­&£ ¨ ¬v¬��&¬ � ¤ ��&»2±6© Ág¨ £ª� � ­&� � �¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬È�k¬�¬v� �¡  ©ª�k£ª£��k��� �¡ º� �Æ­ ¨�¢v¢���t© �¡ «��&§ ¢�¨ Â6£�� � � ² �   »2±6� �wµ � � ¸�k¬   £q¤¥� � ¬v�k��Â6£ª� � �k¬H­&£ ¨ ¬v¬��k¬ � ¤ ��&»�±¶© Ág¨ £�� � ­k� � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬(© ¢�¢��� � ±6­   ©ªÂ6£��&¬� � ��� µ »2±6©_¬v� �¡ H  �i±   �k¬��&¬�¬�� �¡  ©��&£�£ª�k��� �¡ H� ��­ ¨�¢v¢����© �2 «��k§ ¢�¨ Â6£ª�É�   ����k���É­k±6¬ ¿¯6© �6¨ £��&¬ Å ¯¶±6©�¬v»�±¶� ��� �k¬   ­k�i��¯ ¨ ­   �o� � ±6£ª�C£��ë­k� �¡ �¢ � ¸ ¼

ý Í �/2?@9«þ/2�ÿ/ � � ��� � � Tj\8b:� `G\ ��_ \ � _eb�����\ i,b 3,\ X�`�b7V8_�AK ê � à µY²C¸(. �wµ � � ¸`B\�TcTW\ ���e\�)uV��g!`BV� `�? 3�� à µq²�¸!V8_5Z b�`

IjJ µ;�_¸$# µ � ô ¸ ´� � I�� � J � µ�� � ¸ )uV� g!`GV�u`��� � � t��\$��g \8)ag d\$��\,_a`7Z[`;b7V8_'�*? \�`�K.µ�?8¸!V8_a` TW\!]��\,]^\�X-Z ghZSX�`+>\,g-\�X \,_a`;ghZ[T #��% Z*)+)6T b7X-Z[`;b7V8_ãK X V8]�] � `G\ >Z/T Z `G\,_'��V8g b:�,Z[`�b7V8_5ZI48\ X�TW\$��X-Z ghZSX�`+>\,g-\$��#%*_ Z/ZI� �;� b LNM ?�µB1x¸$# µ� ô ¸ ´� � LNM Kwµ;?L¸ÒµB1 � ¸_)uV� g!`GV�u`(1 � 1 � #D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 ��û ��§ ¨�ä ¬ 42© ¨É� � �6�����± � � ����k��� � ¬  �¢�¨g  ©ª� ��� �H­k� ¢���k¬v±6£  �¨g �_¨�� ¬:£ª��­ ¨ ¬:� ®± · �k¬  O� ��­ ¨�¢�¨ ­  «�� ¢ ©�¬   ©�»2±6� � ±6£ª£�� �_¨g� ¬ ÷¥û ��øY¼ Àx¨É����&�o� � ¬  �¢�¨g  ©�� �� � û �i§ ¨�ä ¬ 4�© ¨ü��  «�� ¢ �k¯ ¢ ©�¬v�¹�   ¬�©ª�o¯6£ª©ªæ ��&� �_¨�� ¬ ÷������ ø¶�   æ �_¨ £��k��� �¡  � £�©ª­54�� ¢¨'� � �¶�¹���± � ��¯ ¢ �&± Á �Æ� � ­k� ¢ ��¯6£�±¶¬¹¬�©ª�o¯¶£�� �_¨�� ¬ ÷�� £ªøY¼ Àx¨'����k��� � ¬  �¢�¨g  ©�� �w� �

� £�©ª­54�� ¢ ¬k¤ ¨ ¯6¯6£ª©�»2±6�ß� ¨ © �¡  � �_¨��¡  �o�   ¯°�i± ¢ �o�   � � ­ ¨�¢�¨ ­  «�� ¢ ©ª¬   ©ª»2±6� � � �� ±6£�£ª� Å ¯6±6©ª¬�»2±6�È£���¬��&±6£ ¢���&¬�±6£  è¨g  »2±6©@£�±6©¶� ¨�� »�± ¨ ©  ���  è¨ ©   £q¤¥� ¢v �¦ �i§i� �6¨ £�©  «�� � �k¬­ ¨�¢�¨ ­  �®� ¢ �k¬È¬�± ¢È² µb �¦ ¼ � �_Å ¯6£�±6¬ ¦_¨ ±  &¸ ¼ Àx¨¢ �&£ ¨g  ©�� � � �¡ �¢ �t£��&¬ � ©�¬  �¢ ©ªÂ6±   ©�� � ¬ �¢�¨ ­k�&¬(�&¬   ©���¯6£ª©�»2± ��k�¹¯ ¨�¢ £q¤¥© �¡ «��k§ ¢�¨ Â6©�£ª©  «���£ª�«­ ¨ £�� � �k¬(­ ¨�¢�¨ ­  �®� ¢ �&¬ ®¨ £ ¨ Ç0�i©�¬�¬v± ¢

Page 23: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

�:�²J³�´¶µq·�¸ºµ�÷ À �Îð<ø ¸ �   ¬�± ¢ ��� µ ¯ ¨�¢ ­&�Æ»�±Ä¤[©ª£:�k¬   ­&�i�o¯ ¨ ­   ��� � ±6£��C£ª�ë­k� �¡ �¢ � ¸ ¼

KJ?@9<?@-0-036Ðd9g/ � � � � � � V8b�`. ��_rX-Z ghZSX�`+>\,g-\ ��_eb�`7Z bcg-\ 9S\�� # ��% \,_'��\,]^i�TW\ 9S\$�g \$� `;g b7X�`�b7V8_'� >Zw²�� 9S\$� X-Z ghZSX�`+>\,g-\$� 9S\ `GV� `B\$�4TW\$��g \8)ag d\$��\,_a`7Z[`;b7V8_'� 9S\ X-Z g g d\bc_a`ed\ f8ghZSi�TW\?9S\�² 9S\0X-Z g ZSX�`+>\,g \�X \,_a`�ghZ[To.9\$� `�� _ � � � `+>\,]^\0V8g `�� V8_ V8g ] Z[TuX V8] �)6TW\�` 9S\�T % \$�S) ZSX \�³ à µq²�� � .�¸ � V� 9S\���V8_AX V8]@)6T d\�`ed\���b�TWi \,g `;b7\,_+�#D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 � î ¤¥�k¬  .Á�¢�¨ ©�¯½�i± ¢ ��� �  *³ à µ ��� � .�¸ ¯ ¨�¢ ­k�×»2±6� ����k¬   ­&�i��¯ ¨ ­   ��� � ±6£�� � ¼ < ¨�¢ £ ¨ ­&� ¢�¢ �k¬�¯½� �6�6¨�� ­k�t�  �Á © ¨ £Y¤[©ª¬��i��� ¢ ¯ ¦ ©�¬v�o� "����&æ � ©:¯6£�±¶¬ ¦6¨ ±  �Å ­k� ¢���k¬v±6£  �¨g  �k¬  �Á«¢�¨ © ¨ ±6¬v¬�©:¯½�i± ¢È² ¼

ý Í �/2?@9«þ/2�ÿ/ � ��� � ��� V8b�`j. � _AX-Z ghZSX�`+>\,g \09S\�� #� Z�� �2V��g�`GV� `6153 � µq²�¸_9SV8_a`�T % bc_a`ed\ f8ghZ[TW\�V8g�i,b�`GZ[TW\�\$� `�_ � TcTW\ �2��g�² �;� B ²��b�T \8b:� `B\ ��_ \ �,V8_ X�`;b7V8_A1 � 3 � µ � ��¸�`G\�TcTW\ ���e\41 � 1 � \�` )uV��g^`BV� `�1 3� µq² � .�¸G9SV8_a` T % bc_a`ed\ f8ghZ[TW\!V8g�i,b�`GZ[TW\ \$� ` _ � TcTW\��2��gȲ���� B ²���b�Tj\8b:� `B\�� _ 1 � 3� µ ��� � .�¸@`B\�T ����\�1 � 1 � #� i"� ��V��g4`BV� ` 1 3 � µ ��� ¸!b�T \8b:� `G\ ��_51 � 3 � µY²C¸�`G\�T(����\�1 � 1 � \�`)uV� g!`GV�u`$1 � 3 � µ � � � .�¸�b�T\8b:� `G\ � _ 1 3 � µq² � .�¸0`B\�T ����\�1 � 1 � #D �/2�ÿ?@58��Ì�9<3¶ÌÎÐ0?@5 �Æ���ר ��� �¡ �¢��� µ0 �¦ ¼ � �«¸ »2±6� ² ¨�Ág¨ ©   £ ¨ ¯ ¢ �i¯ ¢ © ��  «�� � ¼À �o§ ¢ �i±6¯½� ��� ¨×¨ ±6¬�¬v©�£ ¨ ¯ ¢ �i¯ ¢ © ��  «�� � ¯ ¨g¢ ­k�o»2±4¤[©ª£H�k¬   ­k�i��¯ ¨ ­   �o� � ±6£ª�£��ã­k� �¡ �¢ ��¼ À �  �¦���&� ¢k®�&�o� � ��­k� ¢v¢ �&¬�¯½� �6�_¨�� ­k��¯6£ª±6¬ ¦_¨ ±   ©���¯6£�©ª»2±6� ¨ £�� ¢ ¬»2±4¤[± � ¯6¬v�k± � �«­&�«��úo­&©�� �2 (� ¤¥± � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� �4? �k¬�¬v� �¡  ©ª�k£ª£��k��� �¡ H� ��­ ¨�¢�¢���© �¡ «��&§ ¢�¨ Â6£�� � � ² ­&� ¢�¢ �k¬v¯°� �¶� ®¨ ± �$µ ¯6¬v�k± � � ¸ ­&�«��úo­&© ¿� �¡ t� � K.µ�?8¸ ��±6£   ©�¯¶£�© ��t¯ ¨�¢�µ � ô ¸ ´� � µ £ª��¯ ¨ ¬�¬ ¨ §i� � �k¬ ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬ � �­ ¨�¢v¢����© �¡ «��k§ ¢�¨ Â6£�� ¨ ±«Ê ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ¬(�k¬v¬�� �¡  ©��k£ª£��&�o� �2 �� ��­ ¨g¢�¢����© �2 «��k§ ¢�¨ Â6£ª�¬���Ç ¨ ©   � �ÿ  � ¢v�_¨��¡  ¯ ¨�¢t� �k¬J­ ¨�¢�¨ ­  �®� ¢ �&¬ ¸ ¼ � � � ­o£ª�k¬t¯6¬��&± � ��­k���&ú�­k©ª� �¡  ¬C¬v� �¢�¨�� ¬vÇ ®� ¢ � �2  ¼ï �i©ª� �¡ �. ± � ­ ¨�¢�¨ ­  �®� ¢ � � � � �  �1 ± � �tÇ0� � ­   ©�� �ü�_¨�� ¬�� µ ��� � .�¸ ¼ ï ©x� �¯°��¬�� �/#&1�� % J LNM ?HµB1x¸N1 J Z� ®±ß£ ¨ ¬��i���o�C¯½� ¢V  ��¬�± ¢ £�� � �i�' ¢ �æ � © � ��­k£ ¨ ¬�¬v�k¬ � � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � ¬ ?� � ��� � �.­ ¨�¢�¨ ­  �®� ¢ �*­k� �¡ �¢�¨ £ . � � �¡  £ ¨+ �¢�¨ ­k� � �*¬&¤ ¨g�6� ±6£��.¯ ¨ ¬�¬�± ¢ 1 �  ků°��± ¢ ­ ¦6¨ »2±6�   �&£ ?�Å�1 J ����k¬�©ª§ � �º± � ¯6¬v�k± � ��­k���&ú�­&©�� �¡ kÅ � �w �¢ �i± Á ��»2±6��¯°�i± ¢  �i±   � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� ��?+� � ��� � ��­ ¨�¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £ .ÈÅ LNM ?Hµ��°¸$# ñ �2­&��»�±¶©©���¯6£�©ª»2±6��»2±6��£Y¤[© �2 «��k§ ¢�¨ £��(� ¢ Â6©  �¨ £�� � � � ¬&¤ ¨��¶� ±¶£���¬�± ¢ £ª�k¬ ��&£ ��&�o� �2  ¬ ¢���&§i±6£�©ª� ¢ ¬� � ��� µ�÷������ ø Å° �¦ ¼��'¼l𫼠¨«ÅÄÁg¨�¢ © ¨��¡  �ð ¸ ¼ ��� � �Ú���� � ±6©   »2±6�C£ ¨ Ç ¨ �o©ª£�£�� � �k¬© �¡ «��&§ ¢�¨ £��k¬º� ¢ ¶©  è¨ £��k¬ � �k¬ µ ¯6¬��&± � � ¸ ­k���&ú�­k©ª� �¡  ¬ � �&¬ ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬ � � � �� ��­ ¨�¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £ . �&¬   ± � �� ¨ ¬v� µq¨ £ª§ ��k ¢ ©�»2±6� ¸ ¯½�i± ¢ £���¬v�i±6¬ ¿ �k¬v¯ ¨ ­&� � �³ µ � � � .�¸ Ç0� ¢ � ��º¯ ¨�¢ £ª�k¬É© �¡ «��k§ ¢�¨ £ª�k¬¹� ¢ Â6©  è¨ £ª�k¬ � �k¬ÉÇ0� � ­   ©ª� � ¬ � ��� µ � � � .�¸ ¼

Page 24: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� � < ¢ � � � � ¬É­&�  v  �ºÇ0��©�¬H± � �ÈÇ0� � ­   ©�� � 1 3 � µY² � .�¸L� � �2  £q¤¥© �¡ «��k§ ¢�¨ £���� ¢ Â6©  �¨ £��¬k¤ ¨��6� ±6£ª�C¬�± ¢ £ª�k¬ ��k£ ��k��� �¡  ¬ë¬v�k��©�¬v©���¯6£��&¬ ¢���&§i±6£ª©�� ¢ ¬ � � � �&£�£�©ª¯   ©ª»2±6�k¬º�   ­k� ��¿¬�© �¹�� ¢ � � ¬�£ ¨ Ç0� � ­   ©ª� � �/#&1�� % J LNM ?HµB1x¸N1 J Z� ®±ë£ ¨ ¬����o����¯°� ¢v  ��¬v± ¢ £�� � ���� ¢ ��æ � © � �H­k£ ¨ ¬�¬��&¬ � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬L�&¬�¬�� �«¿  ©ª�k£�£ª�k��� �¡ H� �È­ ¨�¢v¢���º© �¡ «��&§ ¢�¨ ¶£�� � � ² � �È­ ¨g¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £ .õ� � �¡  £ ¨Æ �¢�¨ ­&�� ��¬k¤ ¨��6� ±6£ª�º¯ ¨ ¬�¬�± ¢ 1 ¼ � ¤ ¨ ¯ ¢k®�k¬�£ ¨ ­k£ ¨ ¬�¬�©ìæ_­ ¨<  ©�� ��� � �Ä�k£ª� Á © � ¬ 42© Å £��&¬�­k£ ¨ ¬�¬v�k¬� ¤ ��k»2±6© Ág¨ £ª� � ­&� � �&¬ ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ¬�»2±6©«¬�� �¡ 8� �k¬�© �6� ±6©   �&¬ µ ¬  �¢ ©�­   �k¬8� �'� � �°¸� � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ¬(�k¬v¬�� �¡  ©��k£ª£��&�o� �2 H� �È­ ¨�¢�¢����© �¡ «��&§ ¢�¨ Â6£��¹Ç0� ¢ ��� �¡  ± � �� ¨ ¬v�� � ² M76FL µY²C¸ ¼ �ã��k­&�i��¯°�i¬v� � ¬�± � � ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � £�©�¬v¬���© ¢v¢��� � ±6­   ©�Â6£ª� ?�� � ²¬�± ¢ ­&�  v  � ¨ ¬v��¼ ï ©�£ª��­ ¨g¢�¨ ­  �®� ¢ �­k� �¡ �¢�¨ £ � � ? �&¬  �.ÈÅ £��C­ ¨�¢�¨ ­  �®� ¢ �C­&� �¡ �¢�¨ £� �w­&�k¬ ¢ �k¯ ¢���k¬v� �¡ è¨g  ©�� � ¬��k¬v¬�� �¡  ©��k£ª£��&�o� �2 '� �.­ ¨�¢�¢���w© �¡ «��k§ ¢�¨ Â6£����i± © �6� ±6©   �&¬� � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � ¬ë�&¬�¬v� �¡  ©ª�k£�£ª�k��� �¡ Æ� ��­ ¨�¢�¢����© �¡ «��k§ ¢�¨ Â6£��J�k¬  t¨ ±6¬�¬v© .ÈÅ ¯ ¨�¢© �6����k¯½� �6�_¨g� ­k�£�© ���� ¨ © ¢ � � �&¬t­ ¨�¢�¨ ­  �®� ¢ �&¬t¬v± ¢�� # · � ¼ é ¨ ©ª¬ë£��&¬  �¢�¨ ­k�k¬ � �k¬¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬O�k¬�¬v� �¡  ©ª�k£ª£��k��� �¡ x� �(­ ¨g¢�¢���H© �2 «��k§ ¢�¨ Â6£ª��¬k¤ ¨��6� ±6£�� �¡  ¬v± ¢ �wµ ¯ ¨g¢¬�©ª�o¯6£ª�ë­ ¨ £ª­k±6£ ¸ �   £��&¬  �¢�¨ ­&�k¬ � �k¬ ¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬�¬  �¢ ©�­   �k��� �¡  © �6� ±¶©   �&¬ � �­ ¨�¢�¨ ­  �®� ¢ ��­&� �¡ �¢�¨ £ . ¬k¤ ¨��6� ±6£�� �¡  ¬v± ¢ � ¯ ¨�¢ ­k�»2±6�£��k¬Æ© �2 «��k§ ¢�¨ £��&¬ë� ¢ ¶©  è¨ £��k¬� � � ¬�� �¡ �� ±6£ª£��&¬8¬�± ¢ £��k¬ ��k£ ��&�o� �¡  ¬8¬v�k��©�¬v©���¯6£��&¬ ¢���k§i±6£ª©�� ¢ ¬ � � � �k£ª£�©�¯   ©�»2±6�&¬L�  ¯ ¨�¢ ­k�Æ»2±6�J£ª�k¬�­ ¨g¢�¨ ­  �®� ¢ �k¬È¬�� �¡  £���­ ¨ £ª�k��� �¡  © �2 «��k§ ¢�¨ Â6£ª�k¬�¬�± ¢È² µ�÷¥À �ÎðQø ¸ ¼ ���� �$�¹�� � ±¶©   »2±6�o£ ¨+ �¢�¨ ­&� � �   �i±   � ¢ �k¯ ¢���k¬�� �¡ è¨g  ©�� � £�©�¬v¬��© ¢v¢��� � ±6­   ©�Â6£ª� � � ²� ��­ ¨�¢�¨ ­  �®� ¢ �º­&� �¡ �¢�¨ £ . �&¬  (� ±6£�£ª��¬�± ¢$� ¼ � � � ­�£Y¤[© �2 «��k§ ¢�¨ £��¹� ¢ Â6©  è¨ £ª� � � � �k¬  � ±6£�£ª��¬�± ¢H  �i±  ���&£ ��k��� �¡  ¬��&�o©ª¬�©ª�o¯6£ª� ¢���&§i±6£ª©�� ¢H� � ² µ�÷������ ø Åi �¦ ¼��'¼l𫼠¨¶Å2Á�¨g¢ © ¿¨��¡  ��ð ¸ ¼ ��� �i   ©�� �¡ �µ ­&�  �  �ÉÇ0�i©�¬L¬�± ¢�²C¸ êO£��&¬�© �¡ «��k§ ¢�¨ £��&¬8� ¢ Â6©  �¨ £��&¬ � �&¬�¯6¬��&± ¿� ��­k���&ú�­k©ª� �¡  ¬ � �k¬ ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ¬��&¬�¬�� �¡  ©��&£�£ª�k��� �¡ �� ��­ ¨�¢�¢���É© �¡ «��&§ ¢�¨ Â6£�� � �­ ¨�¢�¨ ­  �®� ¢ �º­&� �¡ �¢�¨ £ . Ç0� ¢ �o� �2  ± � �ºÂ ¨ ¬�� � ±w¬���±6¬ ¿ �k¬�¯ ¨ ­k� � � ³ µY² � .�¸ Ç0� ¢ � ��¯ ¨�¢ £��&¬¹© �¡ «��k§ ¢�¨ £��&¬¹� ¢ Â6©  �¨ £��&¬ � �k¬¹Ç0� � ­   ©ª� � ¬ � ��� µY² � .�¸�� � �2  £��&¬¹© �¡ «��k§ ¢�¨ £��&¬� ¢ ¶©  è¨ £��k¬¬&¤ ¨��¶� ±¶£�� �¡  ¬v± ¢ £ª�k¬ ��k£ ��&�o� �¡  ¬w¬v�k��©�¬v©���¯6£��&¬ ¢���k§i±¶£�©�� ¢ ¬ � � � �&£�£ª©�¯ ¿  ©ª»�±¶�k¬k¼� ¤ ¨ ¯ ¢k®�&¬H­k��»2±4¤¥� ��Á ©ª� �¡ (� � Á �i© ¢ �   £ª�ÉÇ ¨ ©   »�±¶�È£ª�k¬�¯6¬v�k± � �«­&�«��úo­&©�� �2  ¬ � �k¬¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬��&¬�¬�� �¡  ©��&£�£ª�k��� �¡ �� ��­ ¨�¢v¢���J© �¡ «��&§ ¢�¨ ¶£��Ƭ��  �¢�¨�� ¬vÇ ®� ¢ � �¡ ë�_¨g� ¬£��&¬ � �k±«Êã¬�� � ¬�� � �i   ©�� �2  £ª�k¬È�o�i©   © ��k¬ � �&¬º¯½�i© �¡  ¬ ¨�¸ �    ¸ »2±6©x­k� � ­k� ¢v� � �¡ £��&¬ÉÇ0� � ­   ©�� � ¬ �_¨�� ¬�� µY² � .�¸ �  È�_¨�� ¬�� µ ��� � .�¸ ¼

< ��± ¢ �i   � � © ¢ £ ¨×Ág¨�¢ © ¨��¡  � � ±  �¢�¨�� ¬VÇ0� ¢v  ¯½�i± ¢ £ª�k¬�Ç0� � ­   ©ª� � ¬ ®¨ ¬�±6¯¶¯°� ¢V ­k�i��¯ ¨ ­  �Å ©q¼¥��¼ ¨�¸ �    ¸ ¯½�i± ¢ � µq²�¸ �   � µ � ��¸�Å � � ±   ©ª£�©�¬v�Æ£��  �¦���&� ¢k®�&�o� � �< ¨ £ª� à¡¿XÞ ©ª� � � ¢ ê�¬��i©  �1 ��± � �wÇ0� � ­   ©�� � �6¨�� ¬�� µ ��� ¸ ¼ �᣹�Òʶ©ª¬   � ¨ £�� ¢ ¬'± � �Ç0� � ­   ©�� � 1*�_¨�� ¬*� µY²C¸O  �k£�£ª��»2±6��¯½�i± ¢�  ��±   � ¢ �&¯ ¢���&¬�� �2 �¨g  ©ª� � ? �k¬v¬�� �¡  ©��k£ª£�� ¿�o� �¡ �� �Æ­ ¨�¢v¢���Æ© �¡ «��&§ ¢�¨ Â6£�� � � ² � �ר ©  ô ¸ LNM ?HµB1:¸ # LNM ÷lKwµ;?8¸ ø µG1 � ¸ �  ð ¸ LNM ?HµG1x¸$# ñ�¯½�i± ¢8  �i±   � ¢ �k¯ ¢���k¬v� �¡ è¨<  ©�� � © �6� ±6©   ��¬�± ¢H² µ £��&¬�­k� �6� ©   ©�� � ¬� � < ¨ £ª� à¡¿XÞ ©ª� � � ¢Æµ�÷�� ��� ø ô ¼lð ¸ ¬�� �2 È �¢k®�k¬�Ç ¨ ­&©�£��&¬ ®¨CÁH�� ¢ ©ìæ_� ¢ ¬v± ¢�²t³�´�¸ ¼

Page 25: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �Àx¨ ­&� �6� ©   ©�� � ð ¸ ©ª�o¯6£ª©�»2±6��»2±6�o£q¤¥© �¡ «��&§ ¢�¨ £��C� ¢ Â6©  �¨ £�� � � 1 �&¬  '� ±¶£�£��¬v± ¢£��&¬ ��k£ ��&�o� �¡  ¬�¬��&�o©ª¬�©���¯6£ª�k¬ ¢���k§i±6£ª©�� ¢ ¬ � � � �&£�£�©ª¯   ©ª»2±6�k¬ � � ² ¼Àx¨ ­k� �6� ©   ©�� � ô ¸ ©ª�o¯¶£�©�»2±6�»2±6�.¯½�i± ¢t  �i±   ­ ¨g¢�¨ ­  �®� ¢ � . � � � �  J  �i±   �¢ �&¯ ¢���&¬�� �¡ �¨g  ©ª� � �&¬�¬�� �¡  ©��&£�£ª�k��� �¡ �� �'­ ¨g¢�¢���t© �¡ «��k§ ¢�¨ Â6£�� ?ÿ� � ²"� �'­ ¨g¢�¨ ­  �®� ¢ �­k� �2 �¢�¨ £ . � �Ó¨ LNM ?Hµ^, s4µG1x¸�¸ # LNM Kwµ;?8¸èµ^, s°µG1 � ¸v¸ ¼ Àx¨�����&�o� � ¬  �¢�¨g  ©ª� � ¯6£ª±6¬¦_¨ ±   ©���¯6£�©ª»2±6� ¨ £�� ¢ ¬'»2±6�.£ª�k¬�© �¡ «��k§ ¢�¨ £ª�k¬'� ¢ Â6©  è¨ £ª�k¬ � � , s°µG1x¸ �  C� � , sĵB1 � ¸¬�� �¡ ���&§ ¨ £��&¬�¬�± ¢ £��k¬ ��&£ ��&�o� �2  ¬��k£ª£�©ª¯   ©ª»�±¶�k¬ ¢���k§i±¶£�©�� ¢ ¬�»2±6©8¬��­k� ¢v¢ �&¬�¯½� �6� � �2  ¼� � ¬�� ¢�¨ ¯6¯½�k£ ¨��¡  £ª�J£ª©�� � � �¡ �¢ ��£Y¤[© �2 «��k§ ¢�¨ £��Æ� ¢ Â6©  �¨ £�� � � 1 �   ­k�&£�£ª� � � , sĵB1:¸� �> �¢ �i± Á �Ú»2±6�Ú£��k¬*© �¡ «��k§ ¢�¨ £ª�k¬*� ¢ Â6©  �¨ £��&¬-� µB1 � ¸ �   � µG1 � � ¸o� � 1 �   1 �¢ �&¬�¯½�k­   © Á �k��� �¡  � �¡  £ ¨ ¯ ¢ �i¯ ¢ © ��  «���¬�±¶© Ág¨��¡  �Jê�¯°��± ¢�  �i±  w��&£ ��k��� �¡  �k£ª£�©�¯   ©�»2±6�¢���&§i±6£�©ª� ¢*�w� � ²�Å ¯°�i± ¢�  �i±   ­ ¨�¢�¨ ­  �®� ¢ � .Ö� � �tÅ

O q µ � µG1 � �8�_¸ � � µB1 � � �8� � ¸�¸G.ºµ7��¸H���# ñ t��� � �×�¹�� � ±¶©   ¯ ¨�¢ £ª�  �¦ ¼¥ù6¼[ù Å ­ ¦_¨ ¯Ä¼Sð Å8÷�� �i±¶ø Å »2±6� � µB1 � �_¸ # � µB1 � � � ¸ ¯°�i± ¢  �i±   ��� � �«�  É� � � ­ 1 � 1 �¶�  �1 �¶¬��  �¢�¨g� ¬vÇ ®� ¢ ��¼ À �  �¢�¨g� ¬vÇ0� ¢v É�6¨�� ¬¹£Y¤ ¨ ±  �¢ �¬�� � ¬º¬v�ëÇ ¨ ©  �� �t£ ¨ ����&�o��Ç ¨ �­k� � ¼

A�ÐdÜL-0Ðb?@Ï_9<3¶ØLÍLÐ0/

÷��ɨ ø �J¼ �è¼ �ɨ�� ±6£��&¬�­k± Å6 �¦4®�&¬�� Å ç � © Á ¼ < ¨�¢ ©�¬ ï ± �4Å ô � � �¶¼÷�� �i±¶ø � �i± ¢  ¨ 42© Å�� �@d\YV8g b7\$� �S)u\ X�`�ghZ[TW\$�;!�� ��Z*) #�� ���2Å È� ¢ � ¨��6�ÄÅ < ¨�¢ ©�¬÷ î £ªø À ¼ î £��iö&�k£ Å � �¡Ág¨�¢ © ¨��¡ ×¦_¨g¢ ��� � ©�­ ¨g�_¨ £ à ¬v©�¬+� �B �¦ � ï ­ ¦¡äɨg¢ ö ¬v¯ ¨ ­k�$��Ǩߢ � � ±6­   © Á �oí ¿á¨�� ©ª­ü§ ¢ �i±6¯ Å � g-VYX6#��V� 9SV8bc_�� V8_��*#��� ��� !�� g V f8g \$�;� bc_

� Z[`�� #��eV T #�������Å � © ¢ 4 ¦ "¨ ±6¬v� ¢&Å � �i¬   � �4Å ô � � ô Å ô ñ ô ¿ ô ñið÷������ ø < ¼ � �&£�©ª§ � � Å � ¼ �ƨ ö ¦6�_¨��4Å é ¼ ¿ � ¼ � ©�§ ���� ¢�¨ ¬ Å<û �&¯ ¢���&¬�� �¡ �¨g  ©ª� � ¬ � �&¬ ¨ £�§ ®�& ¢ �&¬

­&� �¡ �¢�¨ £��&¬H¬�©���¯6£ª�k¬4í ¿á¨�� ©�»2±6�&¬ Å���\8)ag d\$��\,_a`7Z[`�b7V8_'��9S\$�*f8g V� )u\$��g d\V9I�eX�`�b � ��2��g�� _AX V8gS) ��TWVYX-Z[T`Å º� ¢ � ¨g�6�4Å < ¨�¢ ©ª¬ ô ����ù6¼÷�� £ªø���¼ � £�©�­54g� ¢&Å � ¢�¨�� ¬VÇ0� ¢ ��Ç ��¢ ¶©  è¨ £ � �¡  �k§ ¢�¨ £ª¬ ¨g�6� � © Á ©ª¬�©ª� � ��£ª§i�k ¢�¨ ¬ Å

� #�*Z ] Z _ �$3 Z _ � Z[`�� # � VYX6# ó µ ô � �iñ ¸�Å ô ñ ¿ ô ð�ð«¼÷ ¿ î ô ø� ¨�¢ ©ª¬ ¦«¿ î ¦_¨��6�¶¢�¨¶Å � � �o©ª¬�¬�©ªÂ6£��'© �¡Ág¨�¢ © ¨��¡ Æ� ©�¬  �¢ ©ªÂ6±   ©�� � ¬ë� �$¢ � � ±6­   © Á �

í ¿p¨�� ©ª­J§ ¢ �i±6¯¶¬ Å?����\ \,_ % ���*Z*)u\,g;� bc_�� � g \ Z _ 9 ��)+)6T b7\ 9 � Z[` � \,] Z[`�b7X$�ù�� µ ô � �� ¸èÅ ð�� ô ¿ � ù «¼

Page 26: Université de Poitiersbadulesc/pub/articol.pdf · "!$# % & ' ( )* + ,.-0/21436587:9=&?@365BAC,*D+E+FHGJILK'E MONQPSR TVUXWYP[ZQ\ TO]_^ UYP`Wbadc egfihkjOUYPlZYm

� �÷ ¿ î ð<ø� ¨�¢ ©ª¬ ¦«¿ î ¦_¨��6�¶¢�¨¶Å �õ¬v±6Â6��� ¢ ¬v©�� � ¯ ¢ © � ­&©�¯6£ª� ¨��¶� ©   ¬ ¨ ¯6¯6£�©ª­ ¨g  ©�� � ¬ Å7� g VYX6# � _ 9 b;Z _

��X-Z+9 # � X6# �iñ µ ô ��� ô ¸èÅ �ió ¿ ô ñið«¼÷ º�&øºòC¼ º� �¶� © ¨�¢V �ÅÄ���� �¦ � Àx¨�� §i£ ¨��¶� ¬�­&� � �v�k­   ± ¢ ��Ç0� ¢�²t³�µ # ¸ ê  �¦ ��­ à ­&£�©ª­­ ¨ ¬�� Å �0_e_6Z[T ��V � � Z[` � # ô ð �+µ ô ��� � ¸èÅ ô ù2ó ¿ ð�ñ � ¼

÷¥Àx¨ øÈòC¼ ÀO¨ ±6�o� �4Å�� V � V8]^V TWV f � b�` � X V8]@) ZSX�`��2� )+)uV8g `�V � � g bc_��,\�T 9 ]^VV9I� �T Z g74oZ g b7\�`�b7\$��Å î ¨ �� ¢ © � §i�Æç � © Á ¼ < ¢ �&¬�¬ Å ô � � «¼÷ À � ô ø � ¼ À �k� ¨ © ¢ � Å� �¦4®�&¬�� Å ç � © Á ¼ < ¨�¢ ©�¬ ï ± �ÄÅ ô � ��ù6¼÷ À �Îð<ø � ¼ À �k� ¨ © ¢ � Å � �2 «��k§ ¢�¨ Â6©ª£�©  «��8£ª�«­ ¨ £�� � �k¬x­ ¨g¢�¨ ­  �®� ¢ �k¬ ¿á� ©ª¬  �¢ ©�Â6±   ©�� � ¬ � � ²t³���µq·�¸� ®± · �k¬   ± � ­k� ¢ ¯6¬�£ª�«­ ¨ £ � � �«¿á¨�¢ ­ ¦ ©�� �� � ©ª� �ü� ��­ ¨g¢�¨ ­  «�� ¢ ©�¬   ©�»2±6�J»2±6�k£ ¿­&� � »2±6� Å�� V8]@)uV ��# � Z[`�� # ô ñ�ñ µ ô � � � ¸èÅ ù ô ¿ ió�¼

÷ À � � ø � ¼ À �k� ¨ © ¢ � Å � �2 «��k§ ¢�¨ £��&¬x� ¢ Â6©  è¨ £ª�k¬°¬�± ¢x²t³�µ��߸ �   ­k� ¢ ¯6¬:£���­ ¨ ±�Ê�¯ ¢ �«­ ¦ �k¬ Å�0_e_ # � _'� ` #��jV��g b7\,g ù � µ ô � � � ¸�Å ô ñ¡ð ¿ ô ñió �¶¼

÷¥û ��ø�¾6¼ û �i§ ¨�ä ¬ 42© Å6û �&¯ ¢ �&¬�� �¡ �¨g  ©ª� � ¬���Ç ²J³�µ # ¸�¨��6�+� © Á ©�¬�©ª� �*¨ £ª§i�k ¢�¨ ¬É� Á � ¢¨ í ¿á¨�� ©ª­�æ_�k£ �4Å � ��8\ � Z[` � # � # ógñ µ ô ��� �2¸èÅ ô � ô ¿ ðgñ ô ¼÷ �Ä�&ø �J¼ �Ä�&£�� Á © � ¬ 42© Å � �¶� ±6­k� �õ¢ �&¯ ¢ �&¬�� �¡ �¨g  ©ª� � ¬'�gÇ ¢ � � ±6­   © Á �Jí ¿á¨�� ©ª­C§ ¢ �i±¶¯6¬� � Å �0_e_ # � X,b�# '� � ô �+µ ô ���iñ ¸�Å ô �¡ó ¿ ð ô ñ«¼