context: It is probable that Lily is a swan. It is probably not the case that Yann is thirsty. There is little chance that Sandra left the milk. It is highly likely that if either 'Yann is thirsty' or 'Lily is a swan' but not both then Julius is a rhino. We believe that if 'Yann is thirsty' or 'Sandra left the milk' or both then Brian is a frog. It is unlikely that if 'Sandra left the milk and Lily is a swan' then Mary went to the garden.
hypothesis: There is a better than even chance that 'Yann is thirsty and Sandra left the milk'.
valid_hypothesis: There is almost no chance that 'Yann is thirsty and Sandra left the milk'.
invalid_hypothesis: There is a better than even chance that 'Yann is thirsty and Sandra left the milk'.
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.
    0.25::factB.
    0.1::factC.
    %hop1
    0.9::factX:-xor(factB,factA).
    0.75::factY:-or(factB,factC).
    0.2::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-and(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Yann is thirsty and Sandra left the milk'.