From ... Path: archiver1.google.com!news2.google.com!newsfeed2.dallas1.level3.net!news.level3.com!zeus.visi.com!news-out.visi.com!petbe.visi.com!news2.telebyte.nl!newsfeed.stueberl.de!newsfeed.vmunix.org!uio.no!nntp.uio.no!not-for-mail From: Erik Naggum Newsgroups: comp.lang.lisp Subject: Re: intersection Date: 28 Jan 2004 23:11:33 +0000 Organization: Naggum Software, Oslo, Norway Lines: 16 Message-ID: <3284320293452997KL2065E@naggum.no> References: <3284290946418800KL2065E@naggum.no> <3284312267277380KL2065E@naggum.no> <401829D4.E0803DDB@motorola.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: readme.uio.no 1075331494 2964 129.240.65.201 (28 Jan 2004 23:11:34 GMT) X-Complaints-To: abuse@uio.no NNTP-Posting-Date: Wed, 28 Jan 2004 23:11:34 +0000 (UTC) Mail-Copies-To: never User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 Xref: archiver1.google.com comp.lang.lisp:11230 * 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.