There is a very good chance that Greg is green. It is improbable that Brian is a lion. We believe that Bernhard is a frog. It is unlikely that if 'Greg is green' or 'Brian is a lion' or both then Emily is a sheep. It is almost certain that if either 'Greg is green' or 'Bernhard is a frog' but not both then Julius is a rhino. Chances are slight that if either 'Greg is green' or 'Bernhard is a frog' but not both then Mary went to the office.
It is highly unlikely that 'Bernhard is a frog' or 'Brian is a lion' or both.
We believe that 'Bernhard is a frog' or 'Brian is a lion' or both.
It is highly unlikely that 'Bernhard is a frog' or 'Brian is a lion' 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
  0.8::factA.
  0.1::factB.
  0.75::factC.
  %hop1
  0.2::factX:-or(factA,factB).
  0.95::factY:-xor(factA,factC).
  0.1::factZ:-xor(factA,factC).

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

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