context: It is impossible that Brian is white. Chances are slight that Antoine is hungry. Chances are slight that Greg is a lion. It is probable that if 'Antoine is hungry and Greg is a lion' then Julius is a swan. It is impossible that if 'Greg is a lion' or 'Antoine is hungry' or both then Lily is a frog. It is probably the case that if 'Greg is a lion and Brian is white' then John went to the bedroom.
hypothesis: There is a very good chance that either 'Brian is white' or 'Lily is a frog' but not both.
valid_hypothesis: It is impossible that either 'Brian is white' or 'Lily is a frog' but not both.
invalid_hypothesis: There is a very good chance that either 'Brian is white' or 'Lily is a frog' but not 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
    0.0::factA.
    0.1::factB.
    0.1::factC.
    %hop1
    0.7::factX:-and(factB,factC).
    0.0::factY:-or(factC,factB).
    0.7::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Brian is white' or 'Lily is a frog' but not both.