context: It is highly likely that Daniel dropped the apple. Chances are about even that Bernhard is a frog. There is a better than even chance that Greg is a lion. We doubt that if either 'Bernhard is a frog' or 'Daniel dropped the apple' but not both then Gertrude is a sheep. It is highly unlikely that if either 'Bernhard is a frog' or 'Greg is a lion' but not both then Julius is white. There is little chance that if 'Greg is a lion and Daniel dropped the apple' then John took the football.
hypothesis: It is highly likely that 'Julius is white' or 'Daniel dropped the apple' or both.
valid_hypothesis: It is highly likely that 'Julius is white' or 'Daniel dropped the apple' or both.
invalid_hypothesis: We doubt that 'Julius is white' or 'Daniel dropped the apple' 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.
    0.5::factB.
    0.6::factC.
    %hop1
    0.2::factX:-xor(factB,factA).
    0.05::factY:-xor(factB,factC).
    0.1::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-or(factY,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is white' or 'Daniel dropped the apple' or both.