There is a better than even chance that Mary went to the kitchen. We doubt that Bernhard is a swan. It is improbable that Lily is yellow. It is likely that if 'Mary went to the kitchen' or 'Lily is yellow' or both then Jessica is a cat. Chances are about even that if either 'Bernhard is a swan' or 'Mary went to the kitchen' but not both then John dropped the apple. It is probable that if either 'Mary went to the kitchen' or 'Lily is yellow' but not both then Julius is a rhino.
There is a better than even chance that 'Mary went to the kitchen' or 'Jessica is a cat' or both.
There is a better than even chance that 'Mary went to the kitchen' or 'Jessica is a cat' or both.
There is little chance that 'Mary went to the kitchen' or 'Jessica is a cat' 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
  0.6::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  0.5::factY:-xor(factB,factA).
  0.7::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Mary went to the kitchen' or 'Jessica is a cat' or both.