context: We doubt that Greg is a rhino. It is probably the case that Mary dropped the milk. We doubt that Brian is a swan. It is probably not the case that if 'Brian is a swan and Mary dropped the milk' then Bernhard is white. There is a better than even chance that if 'Brian is a swan' or 'Greg is a rhino' or both then John went to the hallway. It is probably not the case that if 'Mary dropped the milk and Brian is a swan' then Julius is white.
hypothesis: We believe that 'Greg is a rhino' or 'Bernhard is white' or both.
valid_hypothesis: It is probably not the case that 'Greg is a rhino' or 'Bernhard is white' or both.
invalid_hypothesis: We believe that 'Greg is a rhino' or 'Bernhard is white' or both.
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
    0.2::factA.
    0.7::factB.
    0.2::factC.
    %hop1
    0.25::factX:-and(factC,factB).
    0.6::factY:-or(factC,factA).
    0.25::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-or(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a rhino' or 'Bernhard is white' or both.