CONTENTS X(0)=0),(X T t t s t s t N s X t X),(,0()()(20)()(t m t EX),min(),(2 122 1t t t t X(0)=0),(X T t t!)()()()(ks ts tke k s X t X P t s 0,)()()(s t s X t X E)()()(s t s X t X D t X t X E t EX t mss XX00)()0()()()(),min(),(2 1 2 1t t t t B n(n=1,2,)il0l,2,1,0 i l l li i),0(20 N)(n L)(0n L)(n L 0)()(1 10 0 niiniil E nl l E nl n L E n L E nn222i i 0i=1 i=1E L(n)=E l=E l=n 2 0)()(1 10 0 niiniil E nl l E nl n L E n L E)(n L),0(20 n N,2,1),(n n L nn222i i 0i=1 i=1E L(n)=E l=E l=n 2