context: It is highly unlikely that Greg is a frog. It is highly likely that Lily is a swan. It is unlikely that Bernhard is green. Chances are slight that if 'Greg is a frog' or 'Bernhard is green' or both then Mary went to the hallway. There is almost no chance that if 'Greg is a frog' or 'Bernhard is green' or both then John picked up the apple. It is almost certain that if 'Bernhard is green and Greg is a frog' then Daniel left the football.
hypothesis: We believe that either 'Lily is a swan' or 'Bernhard is green' but not both.
valid_hypothesis: We believe that either 'Lily is a swan' or 'Bernhard is green' but not both.
invalid_hypothesis: Chances are slight that either 'Lily is a swan' or 'Bernhard is green' but not 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
    0.05::factA.
    0.9::factB.
    0.2::factC.
    %hop1
    0.1::factX:-or(factA,factC).
    0.02::factY:-or(factA,factC).
    0.95::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a swan' or 'Bernhard is green' but not both.