Chances are slight that Jeff left the football. It is certain that Fred put down the apple. Chances are about even that Greg is white. Chances are slight that if 'Jeff left the football' or 'Greg is white' or both then Bernhard is yellow. It is likely that if 'Greg is white and Jeff left the football' then Bill got the milk there. It is certain that if either 'Greg is white' or 'Fred put down the apple' but not both then Jessica is a wolf.
It is highly unlikely that 'Bill got the milk there and Greg is white'.
It is highly unlikely that 'Bill got the milk there and Greg is white'.
It is likely that 'Bill got the milk there and Greg is white'.

  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.
  1.0::factB.
  0.5::factC.
  %hop1
  0.1::factX:-or(factA,factC).
  0.7::factY:-and(factC,factA).
  1.0::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Bill got the milk there and Greg is white'.