There is a better than even chance that John grabbed the apple. Chances are slight that Greg is a lion. There is a better than even chance that Bernhard is gray. There is almost no chance that if either 'John grabbed the apple' or 'Greg is a lion' but not both then Daniel got the milk. There is almost no chance that if 'Greg is a lion' or 'John grabbed the apple' or both then Fred went to the garden. There is little chance that if 'John grabbed the apple and Greg is a lion' then Sandra dropped the milk.
It is probable that 'Greg is a lion' or 'Fred went to the garden' or both.
It is improbable that 'Greg is a lion' or 'Fred went to the garden' or both.
It is probable that 'Greg is a lion' or 'Fred went to the garden' 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.
  0.1::factB.
  0.6::factC.
  %hop1
  0.02::factX:-xor(factA,factB).
  0.02::factY:-or(factB,factA).
  0.1::factZ:-and(factA,factB).

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

  query(conclusion).
  
'Greg is a lion' or 'Fred went to the garden' or both.