Chances are slight that Bernhard is gray. It is probable that John dropped the apple. There is a better than even chance that Emily is a wolf. It is highly likely that if 'John dropped the apple' or 'Emily is a wolf' or both then Lily is a frog. It is certain that if 'John dropped the apple' or 'Bernhard is gray' or both then Brian is a rhino. It is almost certain that if either 'John dropped the apple' or 'Emily is a wolf' but not both then Bill went to the kitchen.
We doubt that 'John dropped the apple' or 'Emily is a wolf' or both.
It is highly likely that 'John dropped the apple' or 'Emily is a wolf' or both.
We doubt that 'John dropped the apple' or 'Emily is a wolf' 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.
  0.7::factB.
  0.6::factC.
  %hop1
  0.9::factX:-or(factB,factC).
  1.0::factY:-or(factB,factA).
  0.95::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'John dropped the apple' or 'Emily is a wolf' or both.