From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Roland Winkler Newsgroups: gmane.emacs.help Subject: Re: Non-commutative symbolic multiplication in Calc Date: Tue, 06 Sep 2005 20:36:49 +0200 Organization: FAU Erlangen-Nuernberg Message-ID: References: NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1126032151 4876 80.91.229.2 (6 Sep 2005 18:42:31 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 6 Sep 2005 18:42:31 +0000 (UTC) Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Tue Sep 06 20:42:22 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1ECiN5-000171-A0 for geh-help-gnu-emacs@m.gmane.org; Tue, 06 Sep 2005 20:40:39 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ECiRa-0001sU-Gq for geh-help-gnu-emacs@m.gmane.org; Tue, 06 Sep 2005 14:45:18 -0400 Original-Path: shelby.stanford.edu!newsfeed.stanford.edu!news.tele.dk!news.tele.dk!small.news.tele.dk!fu-berlin.de!uni-berlin.de!news.dfncis.de!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 24 Original-X-Trace: news.dfncis.de tUio/js2lbx/zWQMpRbbgwcfLT90b2rZ73+GUb7psTmt4T User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux) Cancel-Lock: sha1:L86gRQOxxMi8WMtP9wBjlMQ9ksk= Original-Xref: shelby.stanford.edu gnu.emacs.help:133720 Original-To: help-gnu-emacs@gnu.org X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:29262 Archived-At: Neon Absentius writes: >> I doubt that you will get what you want when you just remove the >> assumption that multiplication is commutative. > > Depends on what do you mean by "just" by "remove" and by > "assumption". When I say "suspend the assumption" I mean > (obviously) to also suspend its consequences, for example there > should be a "left" and a "right" division. It depends also on what I > want, which (at the moment of writing at least) is rather modest, I > will be happy if I am able to work on a free group (or a tensor > algebra) and define relations as rewrite rules. > > Ideally the multiplication should not be assumed commutative (or the > variables invertible) unless explicitly declared so. Emacs calc (the way I look at it) is designed to be a powerful, advanced calculator. But it is not a computer algebra system which I would use to address the kind of problem you are talking about.. For example. take a look at Maxima, http://www.ma.utexas.edu/maxima.html. It's now under GPL, and it even has a nice emacs interface. Roland