It is improbable that Fred left the football. It is highly likely that Gertrude is a sheep. It is probably the case that Mary went to the bedroom. It is impossible that if either 'Mary went to the bedroom' or 'Gertrude is a sheep' but not both then Julius is a rhino. It is impossible that if 'Fred left the football' or 'Gertrude is a sheep' or both then Brian is white. There is little chance that if 'Gertrude is a sheep and Fred left the football' then Lily is green.
It is impossible that 'Brian is white and Mary went to the bedroom'.
It is impossible that 'Brian is white and Mary went to the bedroom'.
It is almost certain that 'Brian is white and Mary 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
  0.1::factA.
  0.9::factB.
  0.7::factC.
  %hop1
  0.0::factX:-xor(factC,factB).
  0.0::factY:-or(factA,factB).
  0.1::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Brian is white and Mary went to the bedroom'.