We doubt that Gertrude is a mouse. It is almost certain that Brian is a lion. There is almost no chance that John went to the office. We believe that if 'Gertrude is a mouse and John went to the office' then Lily is a lion. It is highly unlikely that if either 'John went to the office' or 'Gertrude is a mouse' but not both then Julius is gray. It is highly likely that if 'Brian is a lion' or 'Gertrude is a mouse' or both then Sandra grabbed the apple.
It is unlikely that 'Brian is a lion' or 'Julius is gray' or both.
It is almost certain that 'Brian is a lion' or 'Julius is gray' or both.
It is unlikely that 'Brian is a lion' or 'Julius 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
  0.2::factA.
  0.95::factB.
  0.02::factC.
  %hop1
  0.75::factX:-and(factA,factC).
  0.05::factY:-xor(factC,factA).
  0.9::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Brian is a lion' or 'Julius is gray' or both.