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From: schwartz@groucho.cs.psu.edu (Scott Schwartz)
Newsgroups: comp.lang.perl
Subject: Re: regular expressions
Message-ID: <hm2Hs2rr@cs.psu.edu>
Date: 10 Jun 91 02:13:03 GMT
References: <1991Jun4.175023.6509@serval.net.wsu.edu>
	<1991Jun5.183443.11524@intellistor.com>
	<1991Jun06.000718.19691@convex.com>
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In-Reply-To: connolly@convex.convex.COM's message of Thu, 06 Jun 1991 00: 07:18 GMT
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connolly@convex.convex.COM (Dan Connolly) writes:
| What definition of "regular language" are you [Karl Hakimian] working from?
| The definition of regular language I've seen is:

It is a theorem that regular languages are closed under intersection
and negation, which is what he was after.  Unix regexps don't
generally provide a syntax for those things, but that's just
happenstance, especially considering that Thompson's 1968 paper talks
providing those features.