context: We believe that Winona is a cat. It is certain that Brian is a lion. It is unlikely that Gertrude is a sheep. It is probably not the case that if either 'Winona is a cat' or 'Gertrude is a sheep' but not both then Mary moved to the garden. It is unlikely that if 'Winona is a cat' or 'Gertrude is a sheep' or both then Greg is a frog. There is a better than even chance that if 'Winona is a cat and Gertrude is a sheep' then John put down the milk.
hypothesis: It is probably not the case that 'Greg is a frog' or 'John put down the milk' or both.
valid_hypothesis: It is probably not the case that 'Greg is a frog' or 'John put down the milk' or both.
invalid_hypothesis: It is almost certain that 'Greg is a frog' or 'John put down 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
    0.75::factA.
    1.0::factB.
    0.2::factC.
    %hop1
    0.25::factX:-xor(factA,factC).
    0.2::factY:-or(factA,factC).
    0.6::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-or(factY,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a frog' or 'John put down the milk' or both.