context: It is probable that Bill left the football. It is probable that John discarded the apple. It is highly unlikely that Bernhard is a swan. There is little chance that if 'John discarded the apple' or 'Bernhard is a swan' or both then Lily is gray. There is little chance that if 'Bernhard is a swan and John discarded the apple' then Mary took the milk. It is almost certain that if either 'John discarded the apple' or 'Bernhard is a swan' but not both then Greg is a rhino.
hypothesis: Chances are slight that 'Bill left the football' or 'Bernhard is a swan' or both.
valid_hypothesis: It is likely that 'Bill left the football' or 'Bernhard is a swan' or both.
invalid_hypothesis: Chances are slight that 'Bill left the football' or 'Bernhard is a swan' 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
    0.7::factA.
    0.7::factB.
    0.05::factC.
    %hop1
    0.1::factX:-or(factB,factC).
    0.1::factY:-and(factC,factB).
    0.95::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-or(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bill left the football' or 'Bernhard is a swan' or both.