I ask any readers of the book "NonMonotonic Reasoning" by Grigoris   
   Antoniou for help in figuring out the example on   
   page 32 of the text:   
      
   He gives a default theory T= (W,D) with W = {a} and D containing the   
   following defaults:   
      
   delta1 = a: ~b / ~b,  delta2 = b : c / c.   
      
   For process II = (delta1) .....   
      
   For II = (delta2,delta1) we have In(II) = Th(a,c,~b) and Out(II) =   
   {~c,b}   
      
   My quesion is how can II(delta2,delta1) be a Process of T when the   
   Prerequisite of delta 2 ie "b" NEVER occurs   
   in W even after the application of delta 1? I think the only way the   
   text is consistent is if delta2's prerequisite is "~b"   
   and not "b" as printed in the text. That way, application of delta1   
   puts the "~b" consequent into the database. However, the author goes   
   on to say II` = (delta1,delta2) is NOT a process of T thereby   
   contradicting my conjecture.   
      
   Thanks in advance.   
      
   [ comp.ai is moderated ... your article may take a while to appear. ]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)