It is highly unlikely that Bill went to the garden. There is a very good chance that Bernhard is yellow. There is a better than even chance that John left the football. It is highly unlikely that if 'Bernhard is yellow' or 'Bill went to the garden' or both then Brian is green. It is unlikely that if either 'John left the football' or 'Bernhard is yellow' but not both then Gertrude is a wolf. It is highly unlikely that if 'Bernhard is yellow' or 'Bill went to the garden' or both then Mary took the milk.
Chances are about even that 'Mary took the milk and Brian is green'.
It is impossible that 'Mary took the milk and Brian is green'.
Chances are about even that 'Mary took the milk and Brian is green'.

  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.
  0.8::factB.
  0.6::factC.
  %hop1
  0.05::factX:-or(factB,factA).
  0.2::factY:-xor(factC,factB).
  0.05::factZ:-or(factB,factA).

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

  query(conclusion).
  
'Mary took the milk and Brian is green'.