context: It is unlikely that Greg is a rhino. It is certain that Jessica is a sheep. There is almost no chance that Mary went to the office. It is probably not the case that if 'Mary went to the office and Jessica is a sheep' then Brian is a swan. We believe that if 'Mary went to the office' or 'Greg is a rhino' or both then John dropped the apple. It is probable that if 'Greg is a rhino and Jessica is a sheep' then Julius is gray.
hypothesis: It is improbable that 'Jessica is a sheep' or 'Greg is a rhino' or both.
valid_hypothesis: It is certain that 'Jessica is a sheep' or 'Greg is a rhino' or both.
invalid_hypothesis: It is improbable that 'Jessica is a sheep' or 'Greg 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
    0.2::factA.
    1.0::factB.
    0.02::factC.
    %hop1
    0.25::factX:-and(factC,factB).
    0.75::factY:-or(factC,factA).
    0.7::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-or(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Jessica is a sheep' or 'Greg is a rhino' or both.