context: There is a better than even chance that Bernhard is a frog. Chances are about even that Daniel got the football. We doubt that Brian is a rhino. It is probable that if either 'Brian is a rhino' or 'Daniel got the football' but not both then John picked up the apple. There is a very good chance that if 'Brian is a rhino and Daniel got the football' then Julius is gray. It is probable that if 'Daniel got the football and Bernhard is a frog' then Mary went to the office.
hypothesis: Chances are about even that 'Julius is gray and John picked up the apple'.
valid_hypothesis: It is impossible that 'Julius is gray and John picked up the apple'.
invalid_hypothesis: Chances are about even that 'Julius is gray and John picked up the apple'.
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
    0.6::factA.
    0.5::factB.
    0.2::factC.
    %hop1
    0.7::factX:-xor(factC,factB).
    0.8::factY:-and(factC,factB).
    0.7::factZ:-and(factB,factA).
  
    %hop2
    conclusion:-and(factY,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is gray and John picked up the apple'.