There is a better than even chance that Gertrude is a sheep. It is impossible that Fred left the football. There is a better than even chance that Julius is a swan. It is probable that if 'Gertrude is a sheep' or 'Julius is a swan' or both then Lily is white. It is likely that if 'Fred left the football' or 'Julius is a swan' or both then Bill went to the office. There is little chance that if 'Julius is a swan' or 'Fred left the football' or both then Mary dropped the apple.
It is impossible that 'Julius is a swan' or 'Bill went to the office' or both.
There is a better than even chance that 'Julius is a swan' or 'Bill went to the office' or both.
It is impossible that 'Julius is a swan' or 'Bill went to the office' 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
  0.6::factA.
  0.0::factB.
  0.6::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  0.7::factY:-or(factB,factC).
  0.1::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Julius is a swan' or 'Bill went to the office' or both.