It is highly unlikely that Lily is yellow. It is highly unlikely that Jessica is a mouse. It is highly unlikely that John went to the hallway. Chances are slight that if either 'John went to the hallway' or 'Jessica is a mouse' but not both then Julius is a lion. It is highly likely that if either 'Jessica is a mouse' or 'John went to the hallway' but not both then Bernhard is white. There is a better than even chance that if either 'John went to the hallway' or 'Jessica is a mouse' but not both then Greg is green.
It is probably the case that 'Greg is green' or 'Julius is a lion' or both.
It is highly unlikely that 'Greg is green' or 'Julius is a lion' or both.
It is probably the case that 'Greg is green' or 'Julius is a lion' or both.

  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
  0.05::factA.
  0.05::factB.
  0.05::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.9::factY:-xor(factB,factC).
  0.6::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Greg is green' or 'Julius is a lion' or both.