context: It is likely that Lily is a rhino. There is little chance that Brian is white. It is highly unlikely that Greg is a frog. It is certain that if either 'Lily is a rhino' or 'Brian is white' but not both then Julius is white. It is impossible that if 'Brian is white and Greg is a frog' then Mary went to the hallway. Chances are slight that if 'Lily is a rhino' or 'Brian is white' or both then Winona is a wolf.
hypothesis: We believe that 'Lily is a rhino' or 'Julius is white' or both.
valid_hypothesis: We believe that 'Lily is a rhino' or 'Julius is white' or both.
invalid_hypothesis: It is improbable that 'Lily is a rhino' or 'Julius is white' 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
    0.7::factA.
    0.1::factB.
    0.05::factC.
    %hop1
    1.0::factX:-xor(factA,factB).
    0.0::factY:-and(factB,factC).
    0.1::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-or(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Lily is a rhino' or 'Julius is white' or both.