context: There is a better than even chance that Julius is white. It is highly likely that Gertrude is a mouse. There is a very good chance that Lily is green. There is little chance that if 'Lily is green and Julius is white' then Mary left the football. There is almost no chance that if 'Lily is green and Gertrude is a mouse' then Greg is gray. We believe that if 'Gertrude is a mouse and Lily is green' then Brian is white.
hypothesis: It is probable that 'Brian is white and Mary left the football'.
valid_hypothesis: There is almost no chance that 'Brian is white and Mary left the football'.
invalid_hypothesis: It is probable that 'Brian is white and Mary left the football'.
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
    0.6::factA.
    0.9::factB.
    0.8::factC.
    %hop1
    0.1::factX:-and(factC,factA).
    0.02::factY:-and(factC,factB).
    0.75::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-and(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is white and Mary left the football'.