context: There is a very good chance that Gertrude is a sheep. We believe that Greg is a swan. It is probable that Mary moved to the garden. It is improbable that if either 'Gertrude is a sheep' or 'Mary moved to the garden' but not both then John put down the apple. There is little chance that if 'Mary moved to the garden and Greg is a swan' then Bernhard is yellow. There is almost no chance that if either 'Gertrude is a sheep' or 'Greg is a swan' but not both then Jessica is a cat.
hypothesis: It is highly unlikely that 'Greg is a swan and Bernhard is yellow'.
valid_hypothesis: It is highly unlikely that 'Greg is a swan and Bernhard is yellow'.
invalid_hypothesis: There is a very good chance that 'Greg is a swan and Bernhard is yellow'.
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
    0.8::factA.
    0.75::factB.
    0.7::factC.
    %hop1
    0.1::factX:-xor(factA,factC).
    0.1::factY:-and(factC,factB).
    0.02::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a swan and Bernhard is yellow'.