There is almost no chance that Jeff went to the bedroom. There is almost no chance that Greg is a lion. There is a very good chance that Lily is a rhino. It is probably not the case that if 'Jeff went to the bedroom and Lily is a rhino' then Gertrude is a cat. It is highly unlikely that if either 'Greg is a lion' or 'Lily is a rhino' but not both then Mary put down the apple. We believe that if 'Greg is a lion and Jeff went to the bedroom' then Julius is a swan.
It is almost certain that 'Julius is a swan and Jeff went to the bedroom'.
It is impossible that 'Julius is a swan and Jeff went to the bedroom'.
It is almost certain that 'Julius is a swan and Jeff went to the bedroom'.

  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
  0.02::factA.
  0.02::factB.
  0.8::factC.
  %hop1
  0.25::factX:-and(factA,factC).
  0.05::factY:-xor(factB,factC).
  0.75::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Julius is a swan and Jeff went to the bedroom'.