Chances are slight that Mary went to the bedroom. It is impossible that Greg is a frog. It is highly likely that Emily is a mouse. It is certain that if 'Greg is a frog' or 'Mary went to the bedroom' or both then Jessica is a cat. We doubt that if 'Mary went to the bedroom' or 'Emily is a mouse' or both then Fred left the football. It is probably the case that if 'Greg is a frog and Mary went to the bedroom' then Julius is white.
It is improbable that 'Mary went to the bedroom' or 'Julius is white' or both.
It is improbable that 'Mary went to the bedroom' or 'Julius is white' or both.
We believe that 'Mary went to the bedroom' or 'Julius is white' or both.

  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
  0.1::factA.
  0.0::factB.
  0.9::factC.
  %hop1
  1.0::factX:-or(factB,factA).
  0.2::factY:-or(factA,factC).
  0.7::factZ:-and(factB,factA).

  %hop2
  conclusion:-or(factA,factZ).

  query(conclusion).
  
'Mary went to the bedroom' or 'Julius is white' or both.