We doubt that Jessica is a mouse. We doubt that Mary went to the kitchen. There is little chance that Bernhard is yellow. Chances are slight that if 'Mary went to the kitchen' or 'Jessica is a mouse' or both then Lily is a swan. Chances are about even that if either 'Jessica is a mouse' or 'Bernhard is yellow' but not both then Brian is a frog. There is a very good chance that if 'Bernhard is yellow and Mary went to the kitchen' then John left the apple.
It is probably not the case that 'Brian is a frog' or 'Mary went to the kitchen' or both.
It is probably not the case that 'Brian is a frog' or 'Mary went to the kitchen' or both.
It is almost certain that 'Brian is a frog' or 'Mary went to the kitchen' 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
  0.2::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.1::factX:-or(factB,factA).
  0.5::factY:-xor(factA,factC).
  0.8::factZ:-and(factC,factB).

  %hop2
  conclusion:-or(factY,factB).

  query(conclusion).
  
'Brian is a frog' or 'Mary went to the kitchen' or both.