From: ted.kosan@gmail.com   
      
   I am working with a Prolog program that was written in the 1970s and 1980s   
   named PRESS (PRolog Equation Solving System) (http://dream.inf.e   
   .ac.uk/software/press/). In the file pressdir/methods/attrac it states:   
      
   % The "closeness" of all the occurrences of a kernel X in an expression   
   %  Exp is the number of arcs in the smallest subtree of Exp which holds   
   %  all the occurrences of X.   
      
   Does anyone know what the definition of an expression kernel is?   
      
   Thanks in advance,   
      
   Ted Kosan   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)