p(F) p(ELSF ) p(E | LSF )p(LSF ) p(E | LSF )p(LS | F)p(F) ==
p(F) p(F) p(F) = p(E | LS )p(L | F)p(S | F) = 0 p(EL .SF) p(E |
L.S)p(L |
F)p(.S | F)p(F)
== 0
p(F) p(F) p(E.LSF ) = p(E |.LS )p(.L | F)p(S | F) =
0.8×1× 0.9 = 0.72
p(F)
p(E.L.SF) = p(E
|.L.S)p(.L |
F)p(.S | F) =
0.1×1× 0.1= 0.01
p(F) p(E
| F) = 0.72+ 0.01= 0.73
2)同理可求: p(E |.F)
p(E |.F) = p(ELS |.F)+ p(EL.S |.F)+ p(E.LS |.F)+ p(E.L.S |.F) p(ELS.F) p(EL.S.F) p(E.LS.F) p(E.L.S.F) =+ + +
p(.F) p(.F) p(.F) p(.F) p(ELS.F) p(E |
LS.F)p(LS.F) p(E |
LS.F)p(LS |.F)p(.F) = =
p(.F) p(.F) p(.F) = p(E