context: There is little chance that Gertrude is a mouse. It is impossible that Bernhard is gray. There is a better than even chance that Fred moved to the office. There is a very good chance that if 'Fred moved to the office' or 'Gertrude is a mouse' or both then Mary left the milk. Chances are about even that if 'Fred moved to the office and Gertrude is a mouse' then John went to the hallway. It is highly unlikely that if 'Bernhard is gray and Gertrude is a mouse' then Julius is a lion.
hypothesis: It is impossible that 'Bernhard is gray' or 'Fred moved to the office' or both.
valid_hypothesis: There is a better than even chance that 'Bernhard is gray' or 'Fred moved to the office' or both.
invalid_hypothesis: It is impossible that 'Bernhard is gray' or 'Fred moved to the office' 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
    0.1::factA.
    0.0::factB.
    0.6::factC.
    %hop1
    0.8::factX:-or(factC,factA).
    0.5::factY:-and(factC,factA).
    0.05::factZ:-and(factB,factA).
  
    %hop2
    conclusion:-or(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is gray' or 'Fred moved to the office' or both.