Chances are about even that Sandra dropped the milk. There is a better than even chance that Yann is hungry. It is highly unlikely that Mary grabbed the apple. It is probably not the case that if 'Yann is hungry' or 'Sandra dropped the milk' or both then Brian is yellow. It is almost certain that if 'Sandra dropped the milk and Yann is hungry' then Lily is a lion. We doubt that if 'Sandra dropped the milk' or 'Mary grabbed the apple' or both then Greg is a rhino.
There is almost no chance that 'Mary grabbed the apple and Lily is a lion'.
There is almost no chance that 'Mary grabbed the apple and Lily is a lion'.
There is a very good chance that 'Mary grabbed the apple and Lily is a lion'.

  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
  0.5::factA.
  0.6::factB.
  0.05::factC.
  %hop1
  0.25::factX:-or(factB,factA).
  0.95::factY:-and(factA,factB).
  0.2::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Mary grabbed the apple and Lily is a lion'.