There is a very good chance that Mary left the football. We believe that Julius is yellow. There is a very good chance that Greg is yellow. We doubt that if either 'Mary left the football' or 'Julius is yellow' but not both then Lily is gray. There is a better than even chance that if 'Mary left the football' or 'Julius is yellow' or both then John put down the apple. Chances are slight that if either 'Julius is yellow' or 'Mary left the football' but not both then Sandra took the milk.
There is a very good chance that 'Sandra took the milk' or 'Mary left the football' or both.
There is a very good chance that 'Sandra took the milk' or 'Mary left the football' or both.
It is unlikely that 'Sandra took the milk' or 'Mary left the football' 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.
  0.8::factC.
  %hop1
  0.2::factX:-xor(factA,factB).
  0.6::factY:-or(factA,factB).
  0.1::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Sandra took the milk' or 'Mary left the football' or both.