context: Chances are slight that John went to the kitchen. It is impossible that Bernhard is gray. We believe that Brian is a frog. There is a better than even chance that if 'John went to the kitchen' or 'Bernhard is gray' or both then Greg is white. We believe that if 'Brian is a frog' or 'Bernhard is gray' or both then Lily is yellow. There is little chance that if 'John went to the kitchen and Bernhard is gray' then Julius is a swan.
hypothesis: There is a better than even chance that 'Bernhard is gray' or 'Lily is yellow' or both.
valid_hypothesis: There is a better than even chance that 'Bernhard is gray' or 'Lily is yellow' or both.
invalid_hypothesis: It is improbable that 'Bernhard is gray' or 'Lily is yellow' or both.
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
    0.1::factA.
    0.0::factB.
    0.75::factC.
    %hop1
    0.6::factX:-or(factA,factB).
    0.75::factY:-or(factC,factB).
    0.1::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-or(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is gray' or 'Lily is yellow' or both.