Path: csiph.com!xmission!usenet.csail.mit.edu!news.iecc.com!.POSTED.news.iecc.com!nerds-end From: Rock Brentwood Newsgroups: comp.compilers Subject: CEX - Context-Free Expression Filter: update. Date: Sun, 4 Apr 2021 16:55:10 -0500 Organization: Compilers Central Lines: 62 Sender: news@iecc.com Approved: comp.compilers@iecc.com Message-ID: <21-04-003@comp.compilers> References: <07-02-067@comp.compilers> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Injection-Info: gal.iecc.com; posting-host="news.iecc.com:2001:470:1f07:1126:0:676f:7373:6970"; logging-data="58492"; mail-complaints-to="abuse@iecc.com" Keywords: tools, theory Posted-Date: 04 Apr 2021 21:14:02 EDT X-submission-address: compilers@iecc.com X-moderator-address: compilers-request@iecc.com X-FAQ-and-archives: http://compilers.iecc.com Xref: csiph.com comp.compilers:2643 The following is an update of the comp.compilers article "CEX - Context-Free Expression Filter" 2007 February 25 https://compilers.iecc.com/comparch/article/07-02-067 Both an updated and UTF-8 converted version of the original have been posted under comp.theory here: https://groups.google.com/g/comp.theory/c/JTnm83_tWcA The following cites from the original have been updated: > In 1993, the regular expression filter REX was introduced. Notable > amongst its features was that processing was carried out entirely > within an algebraic paradigm. The utility and the algorithms > underlying it have eventually found their way into other applications > (e.g. XML-Query). This was originally in the comp.compilers archive. The latest updates may now be found at GitHub under https://github.com/RockBrentwood/RegEx >CEX is the long-planned successor to REX. It will not handle the full >range of REX functionality, but will process language expressions at >the next stage up the Chomsky hierarchy: Context-Free Expressions. >The Untold Story of Formal Languages >http://federation.g3z.com/CompSci/index.htm#Untold >(Numerous other references may be found on this page, both above and >below this link) Currently linked at: https://web.archive.org/web/20080106150352/http://federation.g3z.com/CompSci/ index.htm#Untold Descriptions only are available, not the PDF's; and has been largely subsumed both by the following and publications recent and pending listed in the references (cited in the comp.theory article): The Algebraic Approach II-V https://www.scribd.com/document/235317956/The-Algebraic-Approach-II-V The new framework for context-free expressions, which is part of a new algebraic foundation for formal language and automata theory laid out in recent publications and elsewhere, is a descendant of the algebraic formulation published in 1963 by Chomsky and Schützenberger. A follow-up note to the 2018 papers that I sent both directly to Chomsky and as an open letter on the recent developments is here: https://www.scribd.com/document/392094748/The-evolution-of-recent-development s-in-formal-language-theory-from-the-1960-s An early draft of the presentation for one of the recent publications may be found here: Co Equalizers and Tensor Products for Idempotent Semirings https://www.scribd.com/document/392094657/Co-Equalizers-and-Tensor-Products-f or-Idempotent-Semirings More details may be found in the comp.theory article.