context: It is improbable that Gertrude is a mouse. There is little chance that Bernhard is a swan. It is likely that Julius is a lion. Chances are slight that if 'Julius is a lion' or 'Gertrude is a mouse' or both then Jeff discarded the milk. There is almost no chance that if 'Julius is a lion and Gertrude is a mouse' then Jessica is a sheep. It is probably not the case that if 'Gertrude is a mouse and Julius is a lion' then John got the apple.
hypothesis: It is highly unlikely that 'Julius is a lion and Bernhard is a swan'.
valid_hypothesis: It is highly unlikely that 'Julius is a lion and Bernhard is a swan'.
invalid_hypothesis: It is almost certain that 'Julius is a lion and Bernhard 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.
    0.1::factB.
    0.7::factC.
    %hop1
    0.1::factX:-or(factC,factA).
    0.02::factY:-and(factC,factA).
    0.25::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-and(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a lion and Bernhard is a swan'.