It is unlikely that Gertrude is a mouse. Chances are slight that Daniel took the football. It is highly likely that Bernhard is a rhino. There is little chance that if 'Bernhard is a rhino and Daniel took the football' then Greg is green. It is probably not the case that if 'Daniel took the football' or 'Bernhard is a rhino' or both then Lily is a lion. It is highly likely that if 'Bernhard is a rhino and Daniel took the football' then John dropped the milk.
It is certain that 'Bernhard is a rhino and John dropped the milk'.
Chances are slight that 'Bernhard is a rhino and John dropped the milk'.
It is certain that 'Bernhard is a rhino and John dropped the milk'.

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

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

  query(conclusion).
  
'Bernhard is a rhino and John dropped the milk'.