It is almost certain that Gertrude is a cat. It is improbable that John moved to the office. There is almost no chance that Daniel left the milk. There is a better than even chance that if 'Gertrude is a cat and John moved to the office' then Sandra got the football. It is probable that if either 'Gertrude is a cat' or 'John moved to the office' but not both then Greg is a rhino. We believe that if 'Daniel left the milk and Gertrude is a cat' then Brian is a swan.
It is impossible that 'Brian is a swan' or 'Gertrude is a cat' or both.
It is almost certain that 'Brian is a swan' or 'Gertrude is a cat' or both.
It is impossible that 'Brian is a swan' 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
  0.95::factA.
  0.1::factB.
  0.02::factC.
  %hop1
  0.6::factX:-and(factA,factB).
  0.7::factY:-xor(factA,factB).
  0.75::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Brian is a swan' or 'Gertrude is a cat' or both.