It is probably the case that Julius is a frog. It is improbable that Gertrude is a cat. It is highly likely that Bernhard is green. Chances are about even that if 'Bernhard is green' or 'Julius is a frog' or both then Sumit is hungry. It is probable that if 'Julius is a frog' or 'Gertrude is a cat' or both then Brian is yellow. There is a better than even chance that if 'Gertrude is a cat and Julius is a frog' then Mary grabbed the milk.
There is little chance that 'Brian is yellow' or 'Bernhard is green' or both.
It is almost certain that 'Brian is yellow' or 'Bernhard is green' or both.
There is little chance that 'Brian is yellow' or 'Bernhard is green' 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
  0.7::factA.
  0.1::factB.
  0.9::factC.
  %hop1
  0.5::factX:-or(factC,factA).
  0.7::factY:-or(factA,factB).
  0.6::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Brian is yellow' or 'Bernhard is green' or both.