context: It is likely that Gertrude is a sheep. It is probable that Greg is a lion. It is highly likely that John got the apple. It is highly unlikely that if 'Greg is a lion and Gertrude is a sheep' then Julius is green. There is almost no chance that if either 'John got the apple' or 'Greg is a lion' but not both then Yann is hungry. It is probably the case that if 'Greg is a lion and John got the apple' then Winona is a wolf.
hypothesis: It is impossible that 'Gertrude is a sheep and Yann is hungry'.
valid_hypothesis: It is impossible that 'Gertrude is a sheep and Yann is hungry'.
invalid_hypothesis: We believe that 'Gertrude is a sheep and Yann is hungry'.
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
    0.7::factA.
    0.7::factB.
    0.9::factC.
    %hop1
    0.05::factX:-and(factB,factA).
    0.02::factY:-xor(factC,factB).
    0.7::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-and(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Gertrude is a sheep and Yann is hungry'.