There is a better than even chance that Lily is yellow. It is highly likely that Brian is a lion. Chances are slight that Fred went to the garden. It is impossible that if 'Lily is yellow and Brian is a lion' then Gertrude is a mouse. We doubt that if 'Fred went to the garden and Lily is yellow' then Julius is a swan. There is little chance that if 'Brian is a lion' or 'Fred went to the garden' or both then John took the football.
It is highly likely that 'Brian is a lion' or 'John took the football' or both.
It is highly likely that 'Brian is a lion' or 'John took the football' or both.
It is highly unlikely that 'Brian is a lion' or 'John took the football' 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.
  0.9::factB.
  0.1::factC.
  %hop1
  0.0::factX:-and(factA,factB).
  0.2::factY:-and(factC,factA).
  0.1::factZ:-or(factB,factC).

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

  query(conclusion).
  
'Brian is a lion' or 'John took the football' or both.