There is little chance that Mary discarded the milk. It is likely that Fred moved to the office. It is almost certain that Lily is a swan. It is impossible that if 'Fred moved to the office' or 'Lily is a swan' or both then Brian is a frog. There is a better than even chance that if 'Mary discarded the milk' or 'Lily is a swan' or both then Greg is a rhino. There is almost no chance that if 'Mary discarded the milk' or 'Lily is a swan' or both then Julius is white.
It is highly likely that 'Greg is a rhino' or 'Fred moved to the office' or both.
It is highly likely that 'Greg is a rhino' or 'Fred moved to the office' or both.
We doubt that 'Greg is a rhino' or 'Fred moved 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
  0.1::factA.
  0.7::factB.
  0.95::factC.
  %hop1
  0.0::factX:-or(factB,factC).
  0.6::factY:-or(factA,factC).
  0.02::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Greg is a rhino' or 'Fred moved to the office' or both.