context: There is almost no chance that Greg is a frog. There is almost no chance that Julius is a swan. It is improbable that John dropped the apple. It is certain that if 'Julius is a swan and Greg is a frog' then Emily is a wolf. It is almost certain that if 'John dropped the apple and Julius is a swan' then Brian is a rhino. It is likely that if 'Greg is a frog' or 'Julius is a swan' or both then Jessica is a cat.
hypothesis: It is certain that 'John dropped the apple' or 'Brian is a rhino' or both.
valid_hypothesis: Chances are slight that 'John dropped the apple' or 'Brian is a rhino' or both.
invalid_hypothesis: It is certain that 'John dropped the apple' or 'Brian is a rhino' 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
    0.02::factA.
    0.02::factB.
    0.1::factC.
    %hop1
    1.0::factX:-and(factB,factA).
    0.95::factY:-and(factC,factB).
    0.7::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-or(factC,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'John dropped the apple' or 'Brian is a rhino' or both.