It is highly unlikely that Brian is white. It is almost certain that Lily is white. It is probably the case that Bernhard is yellow. It is unlikely that if 'Brian is white and Bernhard is yellow' then Fred is in the cinema. We doubt that if 'Brian is white and Bernhard is yellow' then Greg is a rhino. It is highly unlikely that if 'Lily is white and Brian is white' then John left the milk.
There is little chance that 'John left the milk' or 'Lily is white' or both.
It is almost certain that 'John left the milk' or 'Lily is white' or both.
There is little chance that 'John left the milk' or 'Lily is white' or both.

  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.
  0.95::factB.
  0.7::factC.
  %hop1
  0.2::factX:-and(factA,factC).
  0.2::factY:-and(factA,factC).
  0.05::factZ:-and(factB,factA).

  %hop2
  conclusion:-or(factZ,factB).

  query(conclusion).
  
'John left the milk' or 'Lily is white' or both.