context: It is highly likely that Brian is a rhino. It is probably not the case that Bill left the football. There is a very good chance that Lily is a lion. It is impossible that if 'Brian is a rhino and Bill left the football' then Winona is a sheep. It is likely that if 'Bill left the football' or 'Brian is a rhino' or both then John went to the kitchen. It is probably not the case that if either 'Bill left the football' or 'Lily is a lion' but not both then Greg is a frog.
hypothesis: It is impossible that 'Greg is a frog and Winona is a sheep'.
valid_hypothesis: It is impossible that 'Greg is a frog and Winona is a sheep'.
invalid_hypothesis: There is a very good chance that 'Greg is a frog and Winona is a sheep'.
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.
    0.25::factB.
    0.8::factC.
    %hop1
    0.0::factX:-and(factA,factB).
    0.7::factY:-or(factB,factA).
    0.25::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-and(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a frog and Winona is a sheep'.