context: It is unlikely that Greg is yellow. It is highly unlikely that John left the milk. It is probable that Gertrude is a sheep. It is highly unlikely that if 'John left the milk and Greg is yellow' then Sandra got the football. It is certain that if 'Gertrude is a sheep and John left the milk' then Winona is a wolf. It is improbable that if 'Gertrude is a sheep' or 'John left the milk' or both then Brian is green.
hypothesis: It is certain that 'Brian is green and Sandra got the football'.
valid_hypothesis: It is impossible that 'Brian is green and Sandra got the football'.
invalid_hypothesis: It is certain that 'Brian is green and Sandra got the football'.
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
    0.2::factA.
    0.05::factB.
    0.7::factC.
    %hop1
    0.05::factX:-and(factB,factA).
    1.0::factY:-and(factC,factB).
    0.1::factZ:-or(factC,factB).
  
    %hop2
    conclusion:-and(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is green and Sandra got the football'.