context: It is probable that John grabbed the apple. It is probably not the case that Mary took the milk. Chances are slight that Bernhard is a rhino. It is improbable that if 'Mary took the milk' or 'Bernhard is a rhino' or both then Lily is a swan. There is a very good chance that if 'John grabbed the apple and Mary took the milk' then Sandra left the milk. We believe that if either 'John grabbed the apple' or 'Mary took the milk' but not both then Julius is a frog.
hypothesis: It is probable that 'John grabbed the apple and Lily is a swan'.
valid_hypothesis: There is almost no chance that 'John grabbed the apple and Lily is a swan'.
invalid_hypothesis: It is probable that 'John grabbed the apple and Lily is a swan'.
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
    0.1::factX:-or(factB,factC).
    0.8::factY:-and(factA,factB).
    0.75::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'John grabbed the apple and Lily is a swan'.