context: It is unlikely that Julius is a swan. It is highly unlikely that Gertrude is a mouse. We doubt that John went to the office. There is little chance that if 'Julius is a swan and John went to the office' then Lily is gray. We believe that if either 'Julius is a swan' or 'Gertrude is a mouse' but not both then Daniel grabbed the apple. There is almost no chance that if either 'Gertrude is a mouse' or 'John went to the office' but not both then Mary got the football.
hypothesis: It is impossible that 'John went to the office and Mary got the football'.
valid_hypothesis: It is impossible that 'John went to the office and Mary got the football'.
invalid_hypothesis: There is a better than even chance that 'John went to the office and Mary 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.
    0.2::factC.
    %hop1
    0.1::factX:-and(factA,factC).
    0.75::factY:-xor(factA,factB).
    0.02::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-and(factC,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'John went to the office and Mary got the football'.