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From: sreeniva@fas.ri.cmu.edu (R S Sreenivas)
Newsgroups: sci.math,comp.theory
Subject: Formal Languages Question
Keywords: Decidability, Inclusion
Message-ID: <12991@pt.cs.cmu.edu>
Date: 10 May 91 14:58:46 GMT
Organization: Carnegie-Mellon University, CS/RI
Lines: 10


I am looking for a family of languages F such that:

	(i)  F strictly includes the family of regular languages, and 
 	(ii) "Inclusion" must be decidable in F... that is, if L, M are
	languages in F, L \subseteq M should be decidable in F.

Any help will be appreciated.  Thanks in advance!

-R.S.