context: It is unlikely that Winona is a wolf. We doubt that Sandra dropped the apple. There is little chance that Brian is a frog. There is a better than even chance that if either 'Sandra dropped the apple' or 'Brian is a frog' but not both then Daniel got the football. There is a very good chance that if either 'Brian is a frog' or 'Sandra dropped the apple' but not both then John is in the garden. It is certain that if 'Sandra dropped the apple and Brian is a frog' then Bill moved to the office.
hypothesis: It is certain that 'Sandra dropped the apple and John is in the garden'.
valid_hypothesis: Chances are slight that 'Sandra dropped the apple and John is in the garden'.
invalid_hypothesis: It is certain that 'Sandra dropped the apple and John is in 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
    0.2::factA.
    0.2::factB.
    0.1::factC.
    %hop1
    0.6::factX:-xor(factB,factC).
    0.8::factY:-xor(factC,factB).
    1.0::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-and(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Sandra dropped the apple and John is in the garden'.