context: There is a very good chance that Greg is gray. It is unlikely that Bernhard is a rhino. Chances are about even that Emily is a sheep.
hypothesis: It is highly likely that 'Bernhard is a rhino and Emily is a sheep'.
valid_hypothesis: Chances are slight that 'Bernhard is a rhino and Emily is a sheep'.
invalid_hypothesis: It is highly likely that 'Bernhard is a rhino and Emily is a sheep'.
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.
    0.2::factB.
    0.5::factC.
    
  
    %hop2
    conclusion:-and(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a rhino and Emily is a sheep'.