context: There is a very good chance that Lily is a lion. We believe that Sandra dropped the milk. It is unlikely that Brian is gray. There is a better than even chance that if either 'Lily is a lion' or 'Brian is gray' but not both then Gertrude is a mouse. It is almost certain that if 'Lily is a lion' or 'Brian is gray' or both then Bill left the football. It is impossible that if either 'Lily is a lion' or 'Brian is gray' but not both then Antoine is hungry.
hypothesis: There is a very good chance that 'Brian is gray and Sandra dropped the milk'.
valid_hypothesis: Chances are slight that 'Brian is gray and Sandra dropped the milk'.
invalid_hypothesis: There is a very good chance that 'Brian is gray and Sandra dropped the milk'.
problog: 
    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
    0.8::factA.
    0.75::factB.
    0.2::factC.
    %hop1
    0.6::factX:-xor(factA,factC).
    0.95::factY:-or(factA,factC).
    0.0::factZ:-xor(factA,factC).
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is gray and Sandra dropped the milk'.