It is probably the case that Gertrude is a sheep. It is impossible that Winona is a sheep. Chances are about even that John put down the apple. It is likely that if 'John put down the apple and Gertrude is a sheep' then Brian is a rhino. We doubt that if 'Winona is a sheep' or 'Gertrude is a sheep' or both then Bernhard is gray. It is unlikely that if 'Gertrude is a sheep' or 'Winona is a sheep' or both then Julius is white.
It is highly likely that 'Julius is white and Gertrude is a sheep'.
There is little chance that 'Julius is white and Gertrude is a sheep'.
It is highly likely that 'Julius is white 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
  0.7::factA.
  0.0::factB.
  0.5::factC.
  %hop1
  0.7::factX:-and(factC,factA).
  0.2::factY:-or(factB,factA).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Julius is white and Gertrude is a sheep'.