It is certain that Brian is a frog. It is probable that Fred dropped the milk. It is probably the case that Julius is green. It is almost certain that if 'Julius is green and Brian is a frog' then Mary got the apple. It is highly likely that if 'Fred dropped the milk and Julius is green' then Lily is white. Chances are slight that if either 'Brian is a frog' or 'Julius is green' but not both then Winona is a cat.
It is unlikely that 'Brian is a frog' or 'Lily is white' or both.
It is certain that 'Brian is a frog' or 'Lily is white' or both.
It is unlikely that 'Brian is a frog' or 'Lily is white' 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
  1.0::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.95::factX:-and(factC,factA).
  0.9::factY:-and(factB,factC).
  0.1::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Brian is a frog' or 'Lily is white' or both.