context: It is probable that Mary went to the garden. We believe that Lily is a rhino. It is impossible that Sandra took the football.
hypothesis: We believe that either 'Sandra took the football' or 'Lily is a rhino' but not both.
valid_hypothesis: We believe that either 'Sandra took the football' or 'Lily is a rhino' but not both.
invalid_hypothesis: There is little chance that either 'Sandra took the football' or 'Lily is a rhino' 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.
    0.75::factB.
    0.0::factC.
    
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Sandra took the football' or 'Lily is a rhino' but not both.