Chances are about even that John put down the apple. It is impossible that Daniel grabbed the milk. It is certain that Jessica is a mouse. There is a very good chance that if 'John put down the apple' or 'Daniel grabbed the milk' or both then Greg is a lion. It is highly likely that if 'Daniel grabbed the milk' or 'John put down the apple' or both then Brian is a rhino. It is probably not the case that if 'John put down the apple' or 'Jessica is a mouse' or both then Bernhard is a frog.
It is certain that 'Greg is a lion' or 'Brian is a rhino' or both.
Chances are about even that 'Greg is a lion' or 'Brian is a rhino' or both.
It is certain that 'Greg is a lion' or 'Brian is a rhino' 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
  0.5::factA.
  0.0::factB.
  1.0::factC.
  %hop1
  0.8::factX:-or(factA,factB).
  0.9::factY:-or(factB,factA).
  0.25::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Greg is a lion' or 'Brian is a rhino' or both.