6S-1so19S‘gT4dw3 (X+x)d(+x+)d(1+xI+)d= (X+x)d(+x+d= (Xx)d(1+xX)d=(X+)d uolsuna spiemypeq e Kq paindwoo agessew puemypeg EI+YqYIJO (X|1+)d(x)do (X+)d(x)do= (T+治wolX)d=(oYX)d :1:1+Ya:Ta oul FTa aouapina pIA! Suryloowsothing Smo 1 X 0 X t E k E 1 E t X k X :t +1: k e, k 1: e into t 1: e evidence Divide )t +1: k e, k 1: e| k X( P =)t 1: e| k X( P )k 1: e, k X|t +1: k e( P)k 1: e| k X( Pα = )k X|t +1: k e( P)k 1: e| k X( Pα = t +1: k bk 1: f α = recursion: rds a backw a yb computed message rd a Backw )k X| +1 k x( P) +1 k x, k X|t +1: k e( P+1 k x Σ =)k X|t +1: k e( P )k X| +1 k x( P) +1 k x|t +1: k e( P +1 k x Σ = )k X| +1 k x( P) +1 k x|t +2: k e( P) +1 k x| +1 k e( P +1 k x Σ = 9 1–5 Sections 15, Chapter