context: Chances are slight that Jeff discarded the milk. There is almost no chance that Jessica is a sheep. We doubt that Fred put down the apple. We believe that if either 'Jessica is a sheep' or 'Jeff discarded the milk' but not both then Julius is a frog. It is highly likely that if 'Jeff discarded the milk' or 'Jessica is a sheep' or both then John got the milk. It is probably not the case that if either 'Jessica is a sheep' or 'Fred put down the apple' but not both then Brian is yellow.
hypothesis: Chances are slight that 'Jeff discarded the milk' or 'Julius is a frog' or both.
valid_hypothesis: Chances are slight that 'Jeff discarded the milk' or 'Julius is a frog' or both.
invalid_hypothesis: It is highly likely that 'Jeff discarded the milk' or 'Julius is a frog' 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.
    0.02::factB.
    0.2::factC.
    %hop1
    0.75::factX:-xor(factB,factA).
    0.9::factY:-or(factA,factB).
    0.25::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-or(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Jeff discarded the milk' or 'Julius is a frog' or both.