It is highly unlikely that Daniel took the football. There is little chance that Gertrude is a wolf. There is little chance that Greg is a swan. It is probably not the case that if 'Daniel took the football' or 'Greg is a swan' or both then Mary went to the kitchen. There is a very good chance that if 'Greg is a swan and Daniel took the football' then Brian is green. There is almost no chance that if 'Daniel took the football' or 'Gertrude is a wolf' or both then John moved to the garden.
It is impossible that 'Brian is green and Gertrude is a wolf'.
It is impossible that 'Brian is green and Gertrude is a wolf'.
We believe that 'Brian is green and Gertrude is a wolf'.

  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.
  0.1::factB.
  0.1::factC.
  %hop1
  0.25::factX:-or(factA,factC).
  0.8::factY:-and(factC,factA).
  0.02::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Brian is green and Gertrude is a wolf'.