There is little chance that Mary went to the garden. There is little chance that Lily is gray. It is likely that Brian is yellow. It is probably not the case that if 'Brian is yellow and Lily is gray' then John took the football. We doubt that if 'Lily is gray' or 'Brian is yellow' or both then Daniel grabbed the milk. We doubt that if 'Mary went to the garden and Brian is yellow' then Julius is a swan.
We believe that 'Brian is yellow' or 'Lily is gray' or both.
We believe that 'Brian is yellow' or 'Lily is gray' or both.
It is improbable that 'Brian is yellow' or 'Lily is gray' 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.
  0.1::factB.
  0.7::factC.
  %hop1
  0.25::factX:-and(factC,factB).
  0.2::factY:-or(factB,factC).
  0.2::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Brian is yellow' or 'Lily is gray' or both.