s? t?? ????r??t str??? s????t??? ??s?? ?? ????r?t??s ??r t??s? t?? ????r??t s????r??s? ??? ?????t??? ?? str??? s????t??? ????r?t?? ?s t? s????t ? str??? s?q??? s????r??s? t?? ?????? ????r?t?? ?s ?r???s?? ???r? t?? ???t??? str???s ?? t?? ???str??t?? str??? s?? q?????s ?r? s????t?? ????? t?? ???? str???s? ?? ?t??r ??r?s? t? ????? t?? s?t ?? t??t?t??? str??? s?q?????s? t?? str???s ?r? ???t????? s????t?? ?r?? t?? ?s?rs ?? ???? ????s? ???t?????? ??t? t?? str????st str???s t??t ???r??s? t?? s?? r?t?? ?? ?t ?s ??t ??ss???? t? s????t ? str??? t??t ??s?t????? ???tr???t?s t? t?? s?? r?t?? ? str??? t??t ???r??s?s t?? s?? r?t? t?? ???st ?s s????t??? ??? ?r???ss ?s r????t?? ??t?? ???? ?s?r r??????s ?t ???st ,
K}? ?t ?s ?ss???? t??t t?? r?q??r?? ??? ?s ????????? ?t t?? tr??s??tt?rs??? t?? r??????? s????? ?t ?s?r k? t?? ???? ?? t?? i th str??? ?? t?? k th r??????r ??? t?? t?t?? s?? r?t? ???? ??? ?? ???????t?? ?s??? ?q? ?????? ?q? ?????? ?q? ?????? r?s???t?????? ??? ???? ?????t??? ?? t?? str??? s????t??? ??s?? ?? ????r?t??s ?s ????? ?? ????t?r ? ?? ?q? ??????? ??? t? t?? ??t?r??????t?? s??? ?s ????r??t tr??s??t ?? ,
? t??s? ????r?t??s ?s ??t str????t??r??r?? ??? r?q??r?? ?????r ?? t?? ?t?r?t???s ???r??s?s ?? t?? ???? ??? r?????s ??r t?? ?t?r?t??? ????r?t??s ????? ,
?str??ts ? s????? str??? s?q????? ?? s????t??? t?? str????st str???s? ????? ?????? ???str??ts ???t???? str??? s?q?????s ???t??????? ??t? ???? ??r??t str???s ??? s????ts t?? ??st s?q?????? ?t ??s ???? ??s?r??? t??t t?? ??r??r ,
??? t??r? ?r? ??s? ?? st????s t? ???r??? t?? ?s?r t?r??????t ?? ???t???s?r ???? ????????? ???????r ??t??r?s? ????? t?? str??? s????t??? ??s?? ?? ????r?t??s ???? ???? ????s? t???t?? ??r s????? ?s?r ???? s?st??s s? ??r? t?? ??t??s??? t? ???t???s?r ???? ??t?r???????s ??t??r?s ?s ,
str???s ?s t?? ???t??? str???s? ??? ??t? s??? t??t str??? ??t?s ??????? t? r???t????? ?????r s?? r?t? ?????s ????r???? st?rt ??t? t?? str???s ?? t?? ?s?r ????? ??s t?? ?r??t?st ??? ?????? ?????? ?t ?s ??st???? t??t ??t? ???? ?r???????t?? t??s ?s?r ?s ? ???? ?s?r? ??t ? p = Pr p Pn ??? ? m = Pr m Pn ?? t?? ???r??? ??? ?????s P 1 ?r? t?? tr??s??tt?? ,
2? ?r?? ????r?? ??t? t?? t?t?? ?????t?? s?? r?t?s1 s??? t??t ????r??t str??? s?q?????s ??t? ????r??t ????t?s ??? ?? s????t?? ?? t?? ?????st??? s??r??? ??? tr?? ?? t?? s????t?? str??? s?q?????s st?rt? s?? r?t? ???tr???t???s? ??? ?r???t?r????? s?t ???str??t?? ?? t?? ?r???s?? ???r???? ?r? ????????t?? ?? t?? tr??? ?t ??? ?? s??? t??t t?? ?????t?? s?? r?t? ?? t?? s????t?? str??? s?q?????s ?P × SR? ?r? ?????r t??? t?? ?t??r s????t?? s?q?????s ?? t?? ?????st??? s??r??? ???s ??s?r??t??? ??? ?? ?s?? t? ??????? ?????r s?? r?t? ?????s ????? ???r??s??? t?? s??? ?? t?? s??r?? tr??? ,
?tr?? ??t???? t?? j th tr??s??tt?r ??? t?? k th r??????r ? ¯ ? kj ? ??? ??t???? t?? j th tr??s??tt?r ??? t?? k th r??????r ??¯????¯ ? kj ? ????t???? ??? ??t???? t?? j th tr??s??tt?r ??? t?? k th r??????r ? P k ? ?r??s??t ????r ?? t?? k ,
????t s????? tr??s??tt?? ?? t?? k th tr??s??tt?r ??t? ?????s??? ,
t?? s????t?? str???s ?? t?? k th ?s?r ? d k ? ??t?? ?????r ?? t?? str???s ?? t?? k th ?s?r ? s k ? ?????? ,
?tr? ??s ????s? ??s ????r?t???s ??r??t?ss??t q???? ????s ?? ??? ?? ???q?? ???? é??tt??r s??t sé???t????é? ?? séq????? ??s ??? ?st ????s?? ??r?? ?? ??s????? q?? ???t???t ??s séq?????s ??s ???s s?????t sé???t????é?s ?? ????t???t ??? r????r??? ?????st???? ??s ????r?t???s s??t s???????t??? ,