Subject: Re: intersection
From: Erik Naggum <>
Date: 28 Jan 2004 23:11:33 +0000
Newsgroups: comp.lang.lisp
Message-ID: <>

* Paul Dietz
| If the lists are long enough, it becomes preferable to use a linear
| time algorithm with eql hash tables.

  Yes, this is true, but I somehow expect a programmer who works with
  large sets to use a more efficient representation than lists.  E.g.,
  if the set has a finite number of candidate elements, a bit vector is
  a suitable representation, where UNION is implementable with BIT-IOR,
  INTERSECTION with BIT-AND, etc.  I have no idea how long «long enough»
  is, though.  You wouldn't have any empirical data on the threshold?

Erik Naggum | Oslo, Norway                                      2004-028

Act from reason, and failure makes you rethink and study harder.
Act from faith, and failure makes you blame someone and push harder.