context: We believe that Bernhard is a swan. It is highly likely that Jeff went to the garden. We doubt that Brian is a rhino. It is highly likely that if either 'Jeff went to the garden' or 'Brian is a rhino' but not both then John got the apple. There is a very good chance that if 'Bernhard is a swan and Jeff went to the garden' then Sandra grabbed the milk. There is little chance that if 'Jeff went to the garden and Brian is a rhino' then Julius is yellow.
hypothesis: There is almost no chance that 'Brian is a rhino and John got the apple'.
valid_hypothesis: There is almost no chance that 'Brian is a rhino and John got the apple'.
invalid_hypothesis: There is a very good chance that 'Brian is a rhino and John got the apple'.
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
    0.75::factA.
    0.9::factB.
    0.2::factC.
    %hop1
    0.9::factX:-xor(factB,factC).
    0.8::factY:-and(factA,factB).
    0.1::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-and(factC,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a rhino and John got the apple'.