context: It is highly likely that Mary grabbed the milk. It is certain that Lily is a frog. We doubt that Bill went to the garden. Chances are slight that if either 'Bill went to the garden' or 'Mary grabbed the milk' but not both then Jessica is a mouse. We believe that if 'Mary grabbed the milk' or 'Bill went to the garden' or both then Brian is a rhino. It is probable that if 'Mary grabbed the milk' or 'Lily is a frog' or both then Greg is a lion.
hypothesis: Chances are about even that 'Mary grabbed the milk' or 'Greg is a lion' or both.
valid_hypothesis: It is almost certain that 'Mary grabbed the milk' or 'Greg is a lion' or both.
invalid_hypothesis: Chances are about even that 'Mary grabbed the milk' or 'Greg is a lion' 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
    0.9::factA.
    1.0::factB.
    0.2::factC.
    %hop1
    0.1::factX:-xor(factC,factA).
    0.75::factY:-or(factA,factC).
    0.7::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-or(factA,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary grabbed the milk' or 'Greg is a lion' or both.