context: There is a better than even chance that John took the apple. It is probably the case that Sandra got the milk. It is probably the case that Mary went to the hallway.
hypothesis: Chances are about even that either 'Sandra got the milk' or 'John took the apple' but not both.
valid_hypothesis: Chances are about even that either 'Sandra got the milk' or 'John took the apple' but not both.
invalid_hypothesis: It is certain that either 'Sandra got the milk' or 'John took the apple' 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
    0.6::factA.
    0.7::factB.
    0.7::factC.
    
  
    %hop2
    conclusion:-xor(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Sandra got the milk' or 'John took the apple' but not both.