There is a better than even chance that Gertrude is a cat. There is almost no chance that Emily is a mouse. It is unlikely that Mary went to the garden. There is little chance that if 'Gertrude is a cat' or 'Mary went to the garden' or both then John dropped the apple. It is almost certain that if 'Gertrude is a cat and Mary went to the garden' then Lily is yellow. It is impossible that if either 'Emily is a mouse' or 'Gertrude is a cat' but not both then Bernhard is a frog.
It is certain that 'Bernhard is a frog and Gertrude is a cat'.
It is impossible that 'Bernhard is a frog and Gertrude is a cat'.
It is certain that 'Bernhard is a frog and Gertrude is a cat'.

  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
  0.6::factA.
  0.02::factB.
  0.2::factC.
  %hop1
  0.1::factX:-or(factA,factC).
  0.95::factY:-and(factA,factC).
  0.0::factZ:-xor(factB,factA).

  %hop2
  conclusion:-and(factZ,factA).

  query(conclusion).
  
'Bernhard is a frog and Gertrude is a cat'.