context: We believe that Greg is a swan. It is certain that Brian is a frog. We believe that John grabbed the apple. We doubt that if either 'Greg is a swan' or 'Brian is a frog' but not both then Daniel put down the milk. It is likely that if 'Greg is a swan and Brian is a frog' then Julius is yellow. There is a better than even chance that if 'John grabbed the apple and Brian is a frog' then Mary moved to the office.
hypothesis: It is highly unlikely that 'Greg is a swan' or 'Daniel put down the milk' or both.
valid_hypothesis: There is a very good chance that 'Greg is a swan' or 'Daniel put down the milk' or both.
invalid_hypothesis: It is highly unlikely that 'Greg is a swan' or 'Daniel put down the milk' or both.
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
    0.75::factA.
    1.0::factB.
    0.75::factC.
    %hop1
    0.2::factX:-xor(factA,factB).
    0.7::factY:-and(factA,factB).
    0.6::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-or(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a swan' or 'Daniel put down the milk' or both.