It is impossible that John took the football. Chances are about even that Bernhard is a frog. It is certain that Lily is white. There is little chance that if 'Lily is white' or 'Bernhard is a frog' or both then Antoine is hungry. We believe that if either 'Lily is white' or 'Bernhard is a frog' but not both then Mary dropped the milk. It is probably not the case that if 'Lily is white' or 'John took the football' or both then Greg is a rhino.
It is certain that 'Bernhard is a frog and Lily is white'.
Chances are about even that 'Bernhard is a frog and Lily is white'.
It is certain that 'Bernhard is a frog and Lily 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
  0.0::factA.
  0.5::factB.
  1.0::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.75::factY:-xor(factC,factB).
  0.25::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Bernhard is a frog and Lily is white'.