context: It is highly likely that Mary picked up the milk. It is likely that John took the apple. It is highly unlikely that Lily is green.
hypothesis: It is likely that either 'John took the apple' or 'Mary picked up the milk' but not both.
valid_hypothesis: It is probably not the case that either 'John took the apple' or 'Mary picked up the milk' but not both.
invalid_hypothesis: It is likely that either 'John took the apple' 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
    0.9::factA.
    0.7::factB.
    0.05::factC.
    
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John took the apple' or 'Mary picked up the milk' but not both.