Chances are slight that Sandra left the milk. It is unlikely that Bill went to the garden. It is probably the case that John picked up the milk. Chances are about even that if 'Bill went to the garden and Sandra left the milk' then Greg is a frog. There is a very good chance that if 'Sandra left the milk and Bill went to the garden' then Lily is yellow. Chances are slight that if 'Sandra left the milk and John picked up the milk' then Bernhard is green.
There is a better than even chance that 'Sandra left the milk and Lily is yellow'.
There is almost no chance that 'Sandra left the milk and Lily is yellow'.
There is a better than even chance that 'Sandra left the milk and Lily is yellow'.

  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.
  0.2::factB.
  0.7::factC.
  %hop1
  0.5::factX:-and(factB,factA).
  0.8::factY:-and(factA,factB).
  0.1::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Sandra left the milk and Lily is yellow'.