context: There is almost no chance that Bill went to the office. There is little chance that Jason is tired. Chances are slight that Greg is yellow. We believe that if 'Greg is yellow' or 'Jason is tired' or both then Julius is a frog. It is improbable that if 'Greg is yellow' or 'Jason is tired' or both then Mary took the football. It is unlikely that if 'Greg is yellow' or 'Bill went to the office' or both then John moved to the garden.
hypothesis: We believe that 'Julius is a frog and Greg is yellow'.
valid_hypothesis: It is improbable that 'Julius is a frog and Greg is yellow'.
invalid_hypothesis: We believe that 'Julius is a frog and Greg is yellow'.
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
    0.02::factA.
    0.1::factB.
    0.1::factC.
    %hop1
    0.75::factX:-or(factC,factB).
    0.1::factY:-or(factC,factB).
    0.2::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-and(factX,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a frog and Greg is yellow'.