We believe that Mary went to the bedroom. It is likely that Greg is a swan. It is probably not the case that John left the milk. Chances are slight that if 'Greg is a swan and Mary went to the bedroom' then Gertrude is a mouse. Chances are slight that if either 'Greg is a swan' or 'Mary went to the bedroom' but not both then Julius is a lion. We doubt that if 'John left the milk and Greg is a swan' then Bernhard is yellow.
It is probably the case that 'Gertrude is a mouse and Julius is a lion'.
It is impossible that 'Gertrude is a mouse and Julius is a lion'.
It is probably the case that 'Gertrude is a mouse and Julius is a lion'.

  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
  0.75::factA.
  0.7::factB.
  0.25::factC.
  %hop1
  0.1::factX:-and(factB,factA).
  0.1::factY:-xor(factB,factA).
  0.2::factZ:-and(factC,factB).

  %hop2
  conclusion:-and(factX,factY).

  query(conclusion).
  
'Gertrude is a mouse and Julius is a lion'.