There is almost no chance that Gertrude is a cat. It is likely that Brian is white. It is probably not the case that Daniel dropped the milk. It is improbable that if 'Gertrude is a cat' or 'Brian is white' or both then Mary picked up the apple. There is little chance that if 'Daniel dropped the milk' or 'Gertrude is a cat' or both then Lily is a lion. There is little chance that if 'Daniel dropped the milk' or 'Brian is white' or both then Greg is a swan.
It is unlikely that 'Daniel dropped the milk and Brian is white'.
It is unlikely that 'Daniel dropped the milk and Brian is white'.
It is likely that 'Daniel dropped the milk and Brian is white'.

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

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

  query(conclusion).
  
'Daniel dropped the milk and Brian is white'.