context: It is certain that Brian is a frog. It is highly unlikely that Bernhard is green. We doubt that Mary moved to the garden. It is almost certain that if 'Brian is a frog' or 'Mary moved to the garden' or both then Gertrude is a wolf. It is certain that if 'Mary moved to the garden and Brian is a frog' then Daniel left the milk. We doubt that if either 'Bernhard is green' or 'Mary moved to the garden' but not both then Julius is a swan.
hypothesis: It is probable that either 'Brian is a frog' or 'Gertrude is a wolf' but not both.
valid_hypothesis: It is highly unlikely that either 'Brian is a frog' or 'Gertrude is a wolf' but not both.
invalid_hypothesis: It is probable that either 'Brian is a frog' or 'Gertrude is a wolf' 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
    1.0::factA.
    0.05::factB.
    0.2::factC.
    %hop1
    0.95::factX:-or(factA,factC).
    1.0::factY:-and(factC,factA).
    0.2::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-xor(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Brian is a frog' or 'Gertrude is a wolf' but not both.