context: There is a very good chance that Fred left the football. There is almost no chance that Julius is gray. It is improbable that Lily is a rhino. It is highly likely that if 'Fred left the football and Julius is gray' then Bernhard is yellow. It is unlikely that if 'Julius is gray' or 'Lily is a rhino' or both then Mary went to the hallway. It is improbable that if either 'Fred left the football' or 'Lily is a rhino' but not both then Greg is a rhino.
hypothesis: There is a very good chance that either 'Julius is gray' or 'Mary went to the hallway' but not both.
valid_hypothesis: It is highly unlikely that either 'Julius is gray' or 'Mary went to the hallway' but not both.
invalid_hypothesis: There is a very good chance that either 'Julius is gray' or 'Mary went to the hallway' 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
    0.8::factA.
    0.02::factB.
    0.1::factC.
    %hop1
    0.9::factX:-and(factA,factB).
    0.2::factY:-or(factB,factC).
    0.1::factZ:-xor(factA,factC).
  
    %hop2
    conclusion:-xor(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Julius is gray' or 'Mary went to the hallway' but not both.