There is a better than even chance that John went to the hallway. It is highly likely that Gertrude is a cat. It is highly unlikely that Mary took the milk. It is probably not the case that if 'Mary took the milk' or 'Gertrude is a cat' or both then Greg is a rhino. It is certain that if either 'John went to the hallway' or 'Mary took the milk' but not both then Daniel dropped the apple. It is certain that if either 'John went to the hallway' or 'Gertrude is a cat' but not both then Lily is a swan.
There is a better than even chance that 'Daniel dropped the apple' or 'Mary took the milk' or both.
There is a better than even chance that 'Daniel dropped the apple' or 'Mary took the milk' or both.
It is improbable that 'Daniel dropped the apple' or 'Mary took the milk' 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.
  0.05::factC.
  %hop1
  0.25::factX:-or(factC,factB).
  1.0::factY:-xor(factA,factC).
  1.0::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Daniel dropped the apple' or 'Mary took the milk' or both.