context: It is certain that Greg is a frog. We doubt that Mary went to the garden. There is little chance that Lily is a lion.
hypothesis: We believe that 'Greg is a frog and Mary went to the garden'.
valid_hypothesis: It is unlikely that 'Greg is a frog and Mary went to the garden'.
invalid_hypothesis: We believe that 'Greg is a frog and Mary went to the garden'.
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
    1.0::factA.
    0.2::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-and(factA,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a frog and Mary went to the garden'.