It is highly likely that Julius is green. Chances are slight that Greg is a lion. We doubt that Fred discarded the apple. We doubt that if 'Greg is a lion' or 'Julius is green' or both then Brian is yellow. It is certain that if 'Greg is a lion and Fred discarded the apple' then Lily is gray. It is likely that if either 'Julius is green' or 'Fred discarded the apple' but not both then Winona is a mouse.
There is almost no chance that 'Brian is yellow and Greg is a lion'.
There is almost no chance that 'Brian is yellow and Greg is a lion'.
It is probably the case that 'Brian is yellow and Greg 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
  0.9::factA.
  0.1::factB.
  0.2::factC.
  %hop1
  0.2::factX:-or(factB,factA).
  1.0::factY:-and(factB,factC).
  0.7::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Brian is yellow and Greg is a lion'.