There is little chance that Lily is green. It is probably not the case that John picked up the apple. It is probably not the case that Julius is a lion. There is a better than even chance that if 'Julius is a lion and John picked up the apple' then Mary dropped the milk. It is highly likely that if 'John picked up the apple and Julius is a lion' then Greg is gray. It is unlikely that if 'John picked up the apple' or 'Lily is green' or both then Brian is a frog.
It is highly unlikely that 'John picked up the apple and Greg is gray'.
It is highly unlikely that 'John picked up the apple and Greg is gray'.
Chances are about even that 'John picked up 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
  0.1::factA.
  0.25::factB.
  0.25::factC.
  %hop1
  0.6::factX:-and(factC,factB).
  0.9::factY:-and(factB,factC).
  0.2::factZ:-or(factB,factA).

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

  query(conclusion).
  
'John picked up the apple and Greg is gray'.