Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!feeder.news-service.com!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <python-python-list@m.gmane.org>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.000
X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'infinite': 0.07; 'mode,': 0.07; 'terry': 0.07; 'python': 0.07; 'correct.': 0.09; 'default)': 0.09; 'generators': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:80.91.229.12': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'received:lo.gmane.org': 0.09; 'am,': 0.14; 'extension': 0.14; 'wrote:': 0.14; 'iterators,': 0.16; 'lambda': 0.16; 'reedy': 0.16; 'subject:versus': 0.16; 'summary,': 0.16; 'obviously': 0.20; 'jan': 0.22; 'header:In-Reply-To:1': 0.22; '(and': 0.22; 'reference.': 0.23; 'says': 0.25; 'function': 0.27; 'url:edu': 0.28; '(as': 0.29; 'mode': 0.29; 'universal': 0.29; 'operating': 0.30; 'implement': 0.30; 'finite': 0.31; 'to:addr:python-list': 0.32; 'thank': 0.32; 'etc)': 0.33; 'header:X-Complaints-To:1': 0.34; 'describe': 0.35; 'header:User-Agent:1': 0.35; 'subject:software': 0.35; 'machine': 0.37; 'pretty': 0.38; 'received:org': 0.38; 'authors': 0.39; 'machines': 0.39; 'to:addr:python.org': 0.39; 'header:Mime-Version:1': 0.39; 'except': 0.39; 'header:Received:5': 0.40; 'interest': 0.65; 'subject:Free': 0.72; 'papers': 0.74; 'calculus': 0.91
X-Injected-Via-Gmane: http://gmane.org/
To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Free software versus software idea patents
Date: Tue, 12 Apr 2011 13:32:07 -0400
References: <mailman.65.1302065189.9059.python-list@python.org>	<t7Vmp.7632$zn.3197@newsfe19.iad>	<mailman.72.1302078388.9059.python-list@python.org>	<4d9c5ca5$0$29991$c3e8da3$5496439d@news.astraweb.com>	<87tyebf3r3.fsf_-_@benfinney.id.au>	<_Abnp.8356$zn.729@newsfe19.iad>	<4d9d6587$0$29992$c3e8da3$5496439d@news.astraweb.com>	<OHlnp.10535$g56.5872@newsfe04.iad>	<mailman.121.1302206148.9059.python-list@python.org>	<__top.14604$zn.8052@newsfe19.iad>	<mailman.209.1302508440.9059.python-list@python.org> <8d9a097d-1160-4131-8bde-65e8e2ff3240@k5g2000yqj.googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-Gmane-NNTP-Posting-Host: rain.gmane.org
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Lightning/1.0b2 Thunderbird/3.1.9
In-Reply-To: <8d9a097d-1160-4131-8bde-65e8e2ff3240@k5g2000yqj.googlegroups.com>
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.266.1302629543.9059.python-list@python.org>
Lines: 21
NNTP-Posting-Host: 82.94.164.166
X-Trace: 1302629544 news.xs4all.nl 81476 [::ffff:82.94.164.166]:45578
X-Complaints-To: abuse@xs4all.nl
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:3065

On 4/11/2011 4:36 AM, rusi wrote:

> http://www.cse.uconn.edu/~dqg/papers/cie05.pdf
>
> may be of interest (and also other papers of Peter Wegner questioning
> the universality of Turing machines lambda calculus etc)

Thank you for that reference. In summary, it says that while Turing 
machine are universal for finite function calculations, infinite 
interactive processes are not (finite) function calculations, and 
therefore need an extension to TMs. This is pretty obviously correct.

Python iterators, and especially generators, implement the extension 
that the authors call 'persistent Turing machines' (PTMs, section 6.2), 
except that iterators (and generators by default) operate in 'pull' 
mode, while they describe PTMs as operating in 'push' mode (as with 
generator.send()).

-- 
Terry Jan Reedy