context: Chances are about even that Greg is white. It is improbable that Jessica is a mouse. There is a very good chance that Julius is yellow. It is certain that if either 'Jessica is a mouse' or 'Greg is white' but not both then Bernhard is green. It is unlikely that if 'Jessica is a mouse and Julius is yellow' then Daniel grabbed the milk. There is a better than even chance that if 'Greg is white' or 'Jessica is a mouse' or both then Mary dropped the apple.
hypothesis: There is little chance that 'Julius is yellow' or 'Jessica is a mouse' or both.
valid_hypothesis: There is a very good chance that 'Julius is yellow' or 'Jessica is a mouse' or both.
invalid_hypothesis: There is little chance that 'Julius is yellow' or 'Jessica is a mouse' 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
    0.5::factA.
    0.1::factB.
    0.8::factC.
    %hop1
    1.0::factX:-xor(factB,factA).
    0.2::factY:-and(factB,factC).
    0.6::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-or(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is yellow' or 'Jessica is a mouse' or both.