context: Chances are slight that Brian is a rhino. It is almost certain that Julius is green. We believe that Emily is a cat. We doubt that if 'Emily is a cat and Julius is green' then Greg is white. Chances are about even that if 'Brian is a rhino and Emily is a cat' then Jessica is a mouse. There is a better than even chance that if 'Brian is a rhino' or 'Emily is a cat' or both then Bernhard is yellow.
hypothesis: It is probable that 'Julius is green and Brian is a rhino'.
valid_hypothesis: There is little chance that 'Julius is green and Brian is a rhino'.
invalid_hypothesis: It is probable that 'Julius is green and Brian is a rhino'.
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
    0.1::factA.
    0.95::factB.
    0.75::factC.
    %hop1
    0.2::factX:-and(factC,factB).
    0.5::factY:-and(factA,factC).
    0.6::factZ:-or(factA,factC).
  
    %hop2
    conclusion:-and(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is green and Brian is a rhino'.