context: It is probably not the case that Brian is green. It is highly likely that Emily is a sheep. Chances are about even that Lily is a frog. There is little chance that if either 'Lily is a frog' or 'Brian is green' but not both then Julius is yellow. It is highly unlikely that if 'Brian is green and Lily is a frog' then Jeff went to the garden. Chances are slight that if 'Lily is a frog and Brian is green' then John discarded the milk.
hypothesis: Chances are about even that either 'Lily is a frog' or 'Brian is green' but not both.
valid_hypothesis: Chances are about even that either 'Lily is a frog' or 'Brian is green' but not both.
invalid_hypothesis: It is highly unlikely that either 'Lily is a frog' or 'Brian is green' 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
    0.25::factA.
    0.9::factB.
    0.5::factC.
    %hop1
    0.1::factX:-xor(factC,factA).
    0.05::factY:-and(factA,factC).
    0.1::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a frog' or 'Brian is green' but not both.