It is almost certain that Jessica is a mouse. Chances are slight that Greg is yellow. Chances are about even that Mary picked up the milk. It is highly likely that if 'Greg is yellow and Jessica is a mouse' then Julius is gray. There is almost no chance that if 'Mary picked up the milk and Jessica is a mouse' then Jason is tired. We doubt that if 'Jessica is a mouse' or 'Greg is yellow' or both then Bernhard is a swan.
It is impossible that 'Julius is gray and Jason is tired'.
It is impossible that 'Julius is gray and Jason is tired'.
There is a better than even chance that 'Julius is gray and Jason is tired'.

  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
  0.95::factA.
  0.1::factB.
  0.5::factC.
  %hop1
  0.9::factX:-and(factB,factA).
  0.02::factY:-and(factC,factA).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Julius is gray and Jason is tired'.