There is a very good chance that John went to the kitchen. Chances are slight that Greg is a frog. We believe that Jessica is a mouse. It is probably not the case that if 'John went to the kitchen and Jessica is a mouse' then Mary took the milk. We believe that if 'Jessica is a mouse' or 'Greg is a frog' or both then Julius is yellow. There is almost no chance that if 'Jessica is a mouse' or 'John went to the kitchen' or both then Bernhard is gray.
Chances are slight that 'John went to the kitchen and Greg is a frog'.
Chances are slight that 'John went to the kitchen and Greg is a frog'.
There is a better than even chance that 'John went to the kitchen and Greg is a frog'.

  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
  0.8::factA.
  0.1::factB.
  0.75::factC.
  %hop1
  0.25::factX:-and(factA,factC).
  0.75::factY:-or(factC,factB).
  0.02::factZ:-or(factC,factA).

  %hop2
  conclusion:-and(factA,factB).

  query(conclusion).
  
'John went to the kitchen and Greg is a frog'.