There is a very good chance that Julius is white. We believe that John put down the milk. It is certain that Lily is a lion. It is probable that if 'Lily is a lion and Julius is white' then Greg is a frog. We doubt that if either 'John put down the milk' or 'Julius is white' but not both then Mary took the football. It is unlikely that if 'Julius is white and Lily is a lion' then Brian is yellow.
It is unlikely that 'Mary took the football' or 'Brian is yellow' or both.
It is unlikely that 'Mary took the football' or 'Brian is yellow' or both.
It is probable that 'Mary took the football' or 'Brian is yellow' 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
  0.8::factA.
  0.75::factB.
  1.0::factC.
  %hop1
  0.7::factX:-and(factC,factA).
  0.2::factY:-xor(factB,factA).
  0.2::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Mary took the football' or 'Brian is yellow' or both.