It is likely that Greg is a rhino. Chances are about even that Winona is a sheep. There is almost no chance that John discarded the milk. Chances are about even that if 'Greg is a rhino' or 'John discarded the milk' or both then Bernhard is a frog. It is likely that if either 'John discarded the milk' or 'Winona is a sheep' but not both then Lily is a swan. We believe that if 'John discarded the milk and Winona is a sheep' then Mary went to the bedroom.
It is probably the case that 'Mary went to the bedroom and John discarded the milk'.
It is impossible that 'Mary went to the bedroom and John discarded the milk'.
It is probably the case that 'Mary went to the bedroom and John discarded the milk'.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.7::factA.
  0.5::factB.
  0.02::factC.
  %hop1
  0.5::factX:-or(factA,factC).
  0.7::factY:-xor(factC,factB).
  0.75::factZ:-and(factC,factB).

  %hop2
  conclusion:-and(factZ,factC).

  query(conclusion).
  
'Mary went to the bedroom and John discarded the milk'.