context: It is probably the case that Bernhard is a lion. There is a better than even chance that Greg is a rhino. It is highly likely that Fred went to the garden.
hypothesis: It is highly unlikely that 'Greg is a rhino and Bernhard is a lion'.
valid_hypothesis: Chances are about even that 'Greg is a rhino and Bernhard is a lion'.
invalid_hypothesis: It is highly unlikely that 'Greg is a rhino and Bernhard is a lion'.
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
    0.7::factA.
    0.6::factB.
    0.9::factC.
    
  
    %hop2
    conclusion:-and(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a rhino and Bernhard is a lion'.