It is probably not the case that Bernhard is a frog. It is likely that Gertrude is a cat. It is certain that Mary left the football. We doubt that if 'Gertrude is a cat' or 'Mary left the football' or both then John went to the hallway. There is a better than even chance that if either 'Bernhard is a frog' or 'Mary left the football' but not both then Greg is a swan. It is unlikely that if 'Bernhard is a frog' or 'Gertrude is a cat' or both then Brian is gray.
There is almost no chance that 'Mary left the football' or 'Gertrude is a cat' or both.
It is certain that 'Mary left the football' or 'Gertrude is a cat' or both.
There is almost no chance that 'Mary left the football' or 'Gertrude is a cat' 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
  0.25::factA.
  0.7::factB.
  1.0::factC.
  %hop1
  0.2::factX:-or(factB,factC).
  0.6::factY:-xor(factA,factC).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Mary left the football' or 'Gertrude is a cat' or both.