context: It is certain that Lily is a swan. There is a better than even chance that Jeff left the apple. It is probably the case that Brian is a frog. It is probable that if 'Brian is a frog and Lily is a swan' then Bernhard is gray. There is little chance that if 'Lily is a swan and Jeff left the apple' then Antoine is thirsty. There is a better than even chance that if 'Lily is a swan and Jeff left the apple' then Mary went to the office.
hypothesis: It is highly likely that 'Brian is a frog' or 'Jeff left the apple' or both.
valid_hypothesis: It is highly likely that 'Brian is a frog' or 'Jeff left the apple' or both.
invalid_hypothesis: Chances are slight that 'Brian is a frog' or 'Jeff left the apple' 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
    1.0::factA.
    0.6::factB.
    0.7::factC.
    %hop1
    0.7::factX:-and(factC,factA).
    0.1::factY:-and(factA,factB).
    0.6::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-or(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a frog' or 'Jeff left the apple' or both.