It is improbable that Bernhard is a frog. It is highly likely that Brian is a rhino. It is probably the case that Yann is bored. It is probably the case that if 'Bernhard is a frog' or 'Brian is a rhino' or both then Greg is green. There is little chance that if either 'Brian is a rhino' or 'Bernhard is a frog' but not both then John grabbed the apple. We doubt that if either 'Brian is a rhino' or 'Yann is bored' but not both then Jeff went to the hallway.
It is improbable that 'Bernhard is a frog' or 'Brian is a rhino' or both.
It is highly likely that 'Bernhard is a frog' or 'Brian is a rhino' or both.
It is improbable that 'Bernhard is a frog' 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
  0.1::factA.
  0.9::factB.
  0.7::factC.
  %hop1
  0.7::factX:-or(factA,factB).
  0.1::factY:-xor(factB,factA).
  0.2::factZ:-xor(factB,factC).

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

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