Chances are about even that Bernhard is a rhino. It is probably not the case that Lily is a rhino. There is little chance that Greg is white. There is little chance that if 'Lily is a rhino and Greg is white' then Brian is a frog. We doubt that if 'Lily is a rhino' or 'Bernhard is a rhino' or both then John grabbed the apple. It is probably the case that if either 'Lily is a rhino' or 'Greg is white' but not both then Mary went to the bedroom.
It is probably not the case that 'Lily is a rhino' or 'Brian is a frog' or both.
It is probably not the case that 'Lily is a rhino' or 'Brian is a frog' or both.
There is a very good chance that 'Lily is a rhino' or 'Brian is a frog' 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.
  0.25::factB.
  0.1::factC.
  %hop1
  0.1::factX:-and(factB,factC).
  0.2::factY:-or(factB,factA).
  0.7::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Lily is a rhino' or 'Brian is a frog' or both.