context: It is likely that Bernhard is green. It is certain that Emily is a sheep. It is almost certain that Sandra dropped the milk. It is almost certain that if 'Emily is a sheep' or 'Sandra dropped the milk' or both then Winona is a cat. There is a better than even chance that if either 'Sandra dropped the milk' or 'Bernhard is green' but not both then Lily is a frog. It is almost certain that if either 'Emily is a sheep' or 'Sandra dropped the milk' but not both then Mary got the football.
hypothesis: It is highly unlikely that either 'Lily is a frog' or 'Sandra dropped the milk' but not both.
valid_hypothesis: There is a very good chance that either 'Lily is a frog' or 'Sandra dropped the milk' but not both.
invalid_hypothesis: It is highly unlikely that either 'Lily is a frog' or 'Sandra dropped the milk' 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
    0.7::factA.
    1.0::factB.
    0.95::factC.
    %hop1
    0.95::factX:-or(factB,factC).
    0.6::factY:-xor(factC,factA).
    0.95::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-xor(factY,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a frog' or 'Sandra dropped the milk' but not both.