There is little chance that Brian is green. It is impossible that Julius is gray. It is likely that Greg is white. It is likely that if either 'Julius is gray' or 'Greg is white' but not both then Gertrude is a sheep. There is little chance that if either 'Greg is white' or 'Julius is gray' but not both then Mary discarded the milk. Chances are slight that if either 'Julius is gray' or 'Brian is green' but not both then John moved to the office.
There is a better than even chance that 'Brian is green and Gertrude is a sheep'.
It is highly unlikely that 'Brian is green and Gertrude is a sheep'.
There is a better than even chance that 'Brian is green and Gertrude is a sheep'.

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

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

  query(conclusion).
  
'Brian is green and Gertrude is a sheep'.