context: We believe that Jason is tired. Chances are about even that Emily is a mouse. It is certain that Mary dropped the milk. We believe that if 'Mary dropped the milk and Jason is tired' then Winona is a sheep. Chances are slight that if 'Mary dropped the milk and Emily is a mouse' then Lily is a rhino. It is probably the case that if 'Emily is a mouse' or 'Mary dropped the milk' or both then John left the football.
hypothesis: There is almost no chance that 'Jason is tired and John left the football'.
valid_hypothesis: Chances are about even that 'Jason is tired and John left the football'.
invalid_hypothesis: There is almost no chance that 'Jason is tired and John left the football'.
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.
    0.5::factB.
    1.0::factC.
    %hop1
    0.75::factX:-and(factC,factA).
    0.1::factY:-and(factC,factB).
    0.7::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-and(factA,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Jason is tired and John left the football'.