context: It is certain that Bernhard is a frog. It is highly likely that Brian is yellow. There is almost no chance that Julius is a rhino. Chances are slight that if 'Bernhard is a frog and Brian is yellow' then Fred put down the apple. There is a very good chance that if either 'Julius is a rhino' or 'Bernhard is a frog' but not both then Mary moved to the garden. There is almost no chance that if either 'Brian is yellow' or 'Bernhard is a frog' but not both then Gertrude is a mouse.
hypothesis: It is unlikely that either 'Bernhard is a frog' or 'Mary moved to the garden' but not both.
valid_hypothesis: It is unlikely that either 'Bernhard is a frog' or 'Mary moved to the garden' but not both.
invalid_hypothesis: It is likely that either 'Bernhard is a frog' or 'Mary moved to the garden' 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.
    0.9::factB.
    0.02::factC.
    %hop1
    0.1::factX:-and(factA,factB).
    0.8::factY:-xor(factC,factA).
    0.02::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-xor(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Bernhard is a frog' or 'Mary moved to the garden' but not both.