There is a very good chance that John went to the garden. It is probably the case that Brian is yellow. Chances are slight that Lily is green. We believe that if 'Lily is green and John went to the garden' then Mary left the apple. There is little chance that if either 'Brian is yellow' or 'Lily is green' but not both then Bernhard is gray. It is almost certain that if 'John went to the garden and Brian is yellow' then Greg is gray.
It is highly unlikely that 'Mary left the apple and Greg is gray'.
It is highly unlikely that 'Mary left the apple and Greg is gray'.
It is highly likely that 'Mary left the apple and Greg is gray'.

  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.
  0.7::factB.
  0.1::factC.
  %hop1
  0.75::factX:-and(factC,factA).
  0.1::factY:-xor(factB,factC).
  0.95::factZ:-and(factA,factB).

  %hop2
  conclusion:-and(factX,factZ).

  query(conclusion).
  
'Mary left the apple and Greg is gray'.