context: We believe that Jeff went to the garden. It is almost certain that Jason is bored. It is almost certain that Julius is a frog. It is certain that if 'Julius is a frog and Jason is bored' then John moved to the office. We believe that if either 'Julius is a frog' or 'Jason is bored' but not both then Gertrude is a cat. It is probable that if 'Julius is a frog' or 'Jeff went to the garden' or both then Bernhard is a swan.
hypothesis: We doubt that 'Jason is bored' or 'Bernhard is a swan' or both.
valid_hypothesis: It is certain that 'Jason is bored' or 'Bernhard is a swan' or both.
invalid_hypothesis: We doubt that 'Jason is bored' or 'Bernhard is a swan' 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
    0.75::factA.
    0.95::factB.
    0.95::factC.
    %hop1
    1.0::factX:-and(factC,factB).
    0.75::factY:-xor(factC,factB).
    0.7::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-or(factB,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Jason is bored' or 'Bernhard is a swan' or both.