context: It is certain that Lily is a lion. Chances are slight that Jessica is a cat. There is almost no chance that Mary picked up the milk. There is almost no chance that if 'Lily is a lion and Jessica is a cat' then Sandra is in the kitchen. It is likely that if 'Jessica is a cat' or 'Mary picked up the milk' or both then Julius is a rhino. There is almost no chance that if 'Lily is a lion and Jessica is a cat' then Jeff moved to the garden.
hypothesis: It is highly unlikely that either 'Lily is a lion' or 'Mary picked up the milk' but not both.
valid_hypothesis: It is certain that either 'Lily is a lion' or 'Mary picked up the milk' but not both.
invalid_hypothesis: It is highly unlikely that either 'Lily is a lion' or 'Mary picked up 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
    1.0::factA.
    0.1::factB.
    0.02::factC.
    %hop1
    0.02::factX:-and(factA,factB).
    0.7::factY:-or(factB,factC).
    0.02::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-xor(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a lion' or 'Mary picked up the milk' but not both.