context: There is little chance that Greg is a lion. There is a better than even chance that Lily is a swan. It is probably the case that Daniel dropped the apple. It is highly likely that if 'Greg is a lion and Daniel dropped the apple' then Brian is white. It is probably not the case that if 'Lily is a swan and Greg is a lion' then Jessica is a sheep. It is certain that if 'Lily is a swan' or 'Greg is a lion' or both then Gertrude is a mouse.
hypothesis: There is a very good chance that 'Greg is a lion and Lily is a swan'.
valid_hypothesis: It is highly unlikely that 'Greg is a lion and Lily is a swan'.
invalid_hypothesis: There is a very good chance that 'Greg is a lion and Lily is a swan'.
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.
    0.6::factB.
    0.7::factC.
    %hop1
    0.9::factX:-and(factA,factC).
    0.25::factY:-and(factB,factA).
    1.0::factZ:-or(factB,factA).
  
    %hop2
    conclusion:-and(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a lion and Lily is a swan'.