context: It is improbable that Sandra left the milk. There is little chance that Julius is a lion. We believe that Brian is a rhino. Chances are slight that if 'Brian is a rhino and Julius is a lion' then Greg is yellow. We doubt that if 'Sandra left the milk and Julius is a lion' then Mary went to the hallway. It is highly likely that if 'Sandra left the milk' or 'Brian is a rhino' or both then Bill moved to the office.
hypothesis: It is impossible that 'Sandra left the milk and Mary went to the hallway'.
valid_hypothesis: It is impossible that 'Sandra left the milk and Mary went to the hallway'.
invalid_hypothesis: It is certain that 'Sandra left the milk and Mary went to the hallway'.
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.
    0.1::factB.
    0.75::factC.
    %hop1
    0.1::factX:-and(factC,factB).
    0.2::factY:-and(factA,factB).
    0.9::factZ:-or(factA,factC).
  
    %hop2
    conclusion:-and(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Sandra left the milk and Mary went to the hallway'.