Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.icl.net!newsfeed.fjserv.net!colt.net!news-lond.gip.net!news-raspail.gip.net!news.gsl.net!gip.net!grolier!v.t-online.fr!t-online.fr!news.glorb.com!postnews.google.com!o13g2000cwo.googlegroups.com!not-for-mail From: "Mikito Harakiri" Newsgroups: comp.databases,comp.databases.theory Subject: Re: Modeling General Graphs in SQL Date: 28 Dec 2005 10:20:34 -0800 Organization: http://groups.google.com Lines: 14 Message-ID: <1135794034.512651.319730@o13g2000cwo.googlegroups.com> References: <1134680948.716427.27410@f14g2000cwb.googlegroups.com> <1135221474.351644.252410@o13g2000cwo.googlegroups.com> <1135534127.679826.175680@g43g2000cwa.googlegroups.com> <1135784837.139484.287450@g14g2000cwa.googlegroups.com> NNTP-Posting-Host: 148.87.1.172 Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1135794039 4770 127.0.0.1 (28 Dec 2005 18:20:39 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Wed, 28 Dec 2005 18:20:39 +0000 (UTC) In-Reply-To: User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.0; rv:1.7.3) Gecko/20041001 Firefox/0.10.1,gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: o13g2000cwo.googlegroups.com; posting-host=148.87.1.172; posting-account=jduQMA0AAABKdEh0L1SEqrR3hnlHUlAG Xref: dp-news.maxwell.syr.edu comp.databases:46609 comp.databases.theory:35347 paul c wrote: > >>>... which is > >>>widely believed to be inexpresible by standard > >>> SQL. -------------------------------------------------------^^^^^^^^^^ > From "Universality of Data Retrieval Languages" by Alfred V. Aho and > Jeffrey D. Ullman: > > "In this appendix. we prove that the transitive closure of a relation > cannot be couched as an expression of > relational algebra." ----------------------------------------------------^^^^^^^^^^^^^^^^^^^