context: It is probably not the case that Mary went to the bedroom. It is impossible that John discarded the apple. We doubt that Bernhard is a swan. Chances are slight that if 'John discarded the apple' or 'Mary went to the bedroom' or both then Sandra dropped the milk. There is little chance that if 'John discarded the apple' or 'Bernhard is a swan' or both then Brian is a rhino. It is highly likely that if 'John discarded the apple' or 'Bernhard is a swan' or both then Lily is a frog.
hypothesis: There is a better than even chance that 'John discarded the apple' or 'Sandra dropped the milk' or both.
valid_hypothesis: There is almost no chance that 'John discarded the apple' or 'Sandra dropped the milk' or both.
invalid_hypothesis: There is a better than even chance that 'John discarded the apple' or 'Sandra dropped the milk' 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
    0.25::factA.
    0.0::factB.
    0.2::factC.
    %hop1
    0.1::factX:-or(factB,factA).
    0.1::factY:-or(factB,factC).
    0.9::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-or(factB,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'John discarded the apple' or 'Sandra dropped the milk' or both.