Where results make sense

About us   |   Why use us?   |   Reviews   |   PR   |   Contact us

Topic: Context-free languages

    Note: these results are not from the primary (high quality) database.

Journal of the ACM Bibliography Additional Key Words and Phrases: ambiguity, inherent ambiguity, unambiguity, grammars, context-free languages, Chomsky languages, phrase structure languages, production systems, type 2 languages, bounded languages A direct proof of the inherent ambiguity of a simple context-free language. theory.lcs.mit.edu /~jacm/References/maurer1969:256.html   (36 words)

CITIDEL: Viewing 'On deterministic context-free languages, multihead automata, and the power of an auxiliary pushdown store' A deterministic context-free language L0 is described which is log(n)-complete for the family of languages recognized by deterministic log(n)- tape bounded auxiliary pushdown automata in polynomial time. Sudborough, I. and A. Arora, "On Languages Log-Tape Reducible to Context-Free Languages," proceedings of 1976 Conference on Information Sciences and Systems at Johns Hopkins University. It follows that L0 is a and#8220;hardestand#8221; deterministic context-free language (DCFL), since all DCFL's are recognized in polynomial time by deterministic pushdown automata. www.citidel.org /?op=getobj&identifier=oai:ACMDL:articles.803642   (987 words)

Keyword: context free language On the Properties of the Intersection of Petri Net Languages and Context Free Languages. Properties of an Intersection of Classes of Petri Net Languages and CF-Languages. Try our search engine which allows complex field-based queries. www.informatik.uni-hamburg.de /TGI/pnbib/keywords/c/context_free_language.html   (45 words)

Information and Computation Bibliography The algorithm applies to a class of language sampling problems that includes slices of context-free languages as a proper subclass. Preservation of unambiguity and inherent ambiguity in context-free languages. Uniform random generation of strings in a context-free language. theory.lcs.mit.edu /~iandc/References/gorejksm1997:59.html   (272 words)

Context-free grammar - Wikipedia, the free encyclopedia To prove that a given language is not context-free, one may employ the pumping lemma for context-free languages. An alternative and equivalent definition of context-free languages employs non-deterministic push-down automata: a language is context-free if and only if it can be accepted by such an automaton. A formal language is context-free if there is a context-free grammar that generates it. en.wikipedia.org /wiki/Context-free_grammar   (1318 words)

Context-free language - Encyclopedia.WorldSearch The family of context-free languages is closed under concatenation and union but not intersection or difference. There is a pumping lemma for context-free languages, that gives a necessary condition for a language to be context-free. Transductions and context-free languages (Leitfäden der angewandten Mathematik und Mechanik) encyclopedia.worldsearch.com /context-free_language.htm   (248 words)

Context-free grammar - Wikipedia, the free encyclopedia Context-free grammars are powerful enough to describe the syntax of most programming languages; in fact, the syntax of most programming languages are specified using context-free grammars. An alternative and equivalent definition of context-free languages employs non-deterministic push-down automata: a language is context-free if and only if it can be accepted by such an automaton. For instance, given a context-free grammar, one can use the Chomsky Normal Form to construct a polynomial-time algorithm which decides whether a given string is in the language represented by that grammar or not (the CYK algorithm). en.wikipedia.org /wiki/Context-free_grammar   (1310 words)

Recitation 11 Notes Is the complement of an arbitrary context free language context free? Is the complement of a language generated by a deterministic PDA context free? w is in {0,1}*} is not context free. aduni.org /~dimitrik/aduni_stuff/2090/theory/recit11.html   (345 words)

CSC 432 Notes The set of context-free languages is a superset of regular languages. That is, any regular language can be represented as a context-free language, but the reverse is not always true. A context-free language (CFL) can be more expressive than a regular language. web.presby.edu /~wasmith/courses/432/notes/CFLs.htm   (456 words)

formallangfibres For type-2 languages, a theorem of Greibach states the existence of a universal such, i.e., a context-free language L_{gr} such that every other context-free language is a homomorphic pre-image of L_{gr}. ([HK] has a construction of L_{gr} over a 7-element alphabet, but then one can of course find another such universal context-free language over a 2-element alphabet.) References: [G] Sheila A. Greibach: The hardest context-free language. Standard results of formal language theory tell us that for i\in\{0,2,3\} the restriction of U to lang_i still is a bi-fibration, while the restriction of U to lang_1 still is a fibration, but not a cofibration, since homomorphic images of type-1 languages need not be of type 1. www.mta.ca /~cat-dist/catlist/1999/formallangfibres   (335 words)

Context Free Future of EJB, XML Context free languages, and XML is on it's way there. By context-free I mean an absolutely formal language, so that semantic meaning of any expression written in it can not be interpreted depending on context, in other words, it any expression is unequivocal and has one and only one menaing. It's not programming language, but XML's self-descriptivness, schema, validation, etc. can help in development of a context free programming language of the future. www.theserverside.com /discussions/thread.tss?thread_id=6162   (633 words)

CmSc 365 Theory of Computation The meaning of this theorem is that there exist context-free languages whose intersection is not a context-free language Theorem 1: The class of languages, accepted by push-down automata is exactly the class of context-free languages Theorem 3: The intersection of a context-free language with a regular language is a context-free language. www.simpson.edu /~sinapova/cmsc365-02/L08-CFLsTheorems.htm   (221 words)

Read about Category:Formal languages at WorldVillage Encyclopedia. Research Category:Formal languages and learn about Category:Formal languages here! This document is licensed under the GNU Free List of formal language and literal string topics Documentation License (GFDL), which means that you can encyclopedia.worldvillage.com /s/b/Category:Formal_languages   (52 words)

CSC320_K92_Final.txt Prove or give a counter example that (a) The set of regular languages is a subset of the set of languages accepted by an FSM-2M. Question 5 Give a grammar in CNF for the language consisting of all strings of a's and b's where the number of a's is not equal to the number of b's. (g) A CFL is a recursively enumerable language (h) The intersection of a CFL and a recursively enumerable language is recursive (i) The intersection of a CFL and a recursive language is recursive (j) My answers to (f) through (i) are all correct. www.csc.uvic.ca /~csunion/exams/CSC320_K92_Final.txt   (406 words)

ContextFreeSlides5.doc Example: {anbncn} Showing that a Language is Context-Free Techniques for showing that a language L is context-free: Exhibit a context-free grammar for L. Exhibit a PDA for L. Use the closure properties of context-free languages. The Deterministic Context-Free Languages Are Closed Under Complement Proof: Let L be a language such that L$ is accepted by the deterministic PDA M. We construct a deterministic PDA M' to accept (the complement of L)$, just as we did for FSMs: Initially, let M' = M. M' is already deterministic. The context free pumping lemma applies to L. Let M be the number from the pumping lemma. www.cs.utexas.edu /users/cline/ear/Slides/ContextFree/ContextFreeSlides5.doc   (2069 words)

Theoretische Informatica Club Context-free valence languages (over Z^k) are shown to be codings of the intersection of a context-free language and a blind k-counter language. This AFL-style characterization allows one to infer some of the properties of the family of valence languages, in particular the lambda-free normal form proved by Fernau and Stiebe. The proof is based on a bridge theorem which can also be used to prove that the composition of attribute grammars and of macro tree transducers yield proper hierarchies. www.liacs.nl /~mtbeek/tic01.html   (153 words)

Program Files\Netscape\Communicator\Program\UAExp\CFGs Context-free grammars where originally developed by Noam Chomsky as a means for describing the underlying syntax (grammar) of natural languages. Despite this fact, context-free grammars are still very useful and reflect the underlying algebraic structure of both kinds of languages. We will later give an example of a programming language, the language LANG1, that does have a context-free grammar. www.ii.uib.no /~wagner/UASCR/CFGs.htm   (663 words)

February: Context Free Language In math, there exist a language called Context Free Language, which has a even be conveniently used program computers to produce human languages. in the near future, natural human languages and mathematics could merge www.math.yorku.ca /Who/Faculty/Steprans/Courses/3500/m0302/0015.html   (189 words)

Program Files\Netscape\Communicator\Program\UAExp\CFGs Despite this fact, context-free grammars are still very useful and reflect the underlying algebraic structure of both kinds of languages. Context-free grammars where originally developed by Noam Chomsky as a means for describing the underlying syntax (grammar) of natural languages. We will later give an example of a programming language, the language LANG1, that does have a context-free grammar. www.ii.uib.no /~wagner/UASCR/CFGs.htm   (663 words)

Computational Theory and Formal Languages - Languages of type 2 - context-free and Push-down Automata Example: A context-free grammar is specified by the sets: N={S,A,B}, T={a,b},S is the start symbol, the rules R are defined as below: If Lis a non-empty context-free language, it can be generated by a context-free grammar G with the following properties: Relations between LR(k) grammar and Push-down Automata are given in Table 11 In Tables 12 oraz 13 are given examples of LR(k) grammars with k=1 and k=3. wuwuwu.com.pl /jf/teo7-e.htm   (1264 words)

Information and Control -- 1971 Complexity and unambiguity of context-free grammars and languages. A few remarks on the index of context-free grammars and languages. The generative capacity of transformational grammars of Ginsburg and Partee. theory.lcs.mit.edu /~iandc/ic71.html   (330 words)

Information and Control -- 1975 Generalizations of regular sets and their applicatin to a study of context-free languages. The characterization by automata of certain classes of languages in the context sensititve area. On the syntactic structures of unrestricted grammars I. generative grammars and phrase structure grammars. theory.lcs.mit.edu /~iandc/ic75.html   (340 words)

Citations: Decidability of bisimulation equivalence for processes generating context-free languages - Baeten, Bergstra, Klop (ResearchIndex) Context free languages are accepted by both context free grammars, and pushdown automata. Context free rewriting systems have been used for description and analysis for several classes of infinite state systems such as BPA and pushdown processes (e.g. As an example, a ] b is context free as it is a solution for X 1 in X 1 = aX 1 X 2 b; X 2 = a. citeseer.csail.mit.edu /context/33832/0   (340 words)

context-free language A terminal (that is, a symbol in the alphabet Sigma) is often represented as itself, though in the context of computer languages a terminal symbol is often enclosed in single quotes. Permission is granted to copy, distribute and/or modify these documents under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License." www.citidel.org /dlxml/oai_dc-oai:PlanetMath:ContextFreeLanguage.xml   (340 words)

PlanetMath: context-free language ) is often represented as itself, though in the context of computer languages a terminal symbol is often enclosed in single quotes. www.planetmath.org /encyclopedia/ContextFreeLanguage.html   (340 words)

Context Free and Context Sensitive Languages Most agree that language is a static system, where words are part of a lexicon that is assumed to be context free and static — that is, it is a data structure that exists independently of it’s use. Further simulations were carried out to see if the SCNs could generalize on a Context Free Language (CFL). The SRN was a three layer feed forward network with a “context” layer that was used as input into the hidden layer at each time step. www.itee.uq.edu.au /~pennyd/LangSummaries.htm   (340 words)

CMSC 451 Lecture 24, Pumping Lemma for Context Free Languages To prove a language is not context free requires a specific definition of the language and the use of the Pumping Lemma for Context Free Languages. xSx for all x in Sigma Some languages that are NOT Context Free Languages L={ww If a Context Free Grammar can be constructed to exactly generate the strings in a language, then the language is Context Free. www.cs.umbc.edu /~squire/s01-451/cs451_l24.html   (340 words)

PlanetMath: context-free language The syntaxes of most programming languages are context-free grammars (or very close to it). A context-free grammar is a grammar that generates a context-free language. Context-free grammars are also known as Type-2 grammars in the Chomsky hierarchy. planetmath.org /encyclopedia/ContextFreeGrammar.html   (440 words)

Context free schemas for data-XML Not all languages (or structures) are context free, but it is usually worth the trouble making them so (or nearly). A context free grammar (CFG) is often the most compact and easiest way to describe some structure. refers to context free grammars, on which this proposal is based. www.w3.org /People/Bos/Schema/schemas   (440 words)

Try your search on: Qwika (all wikis)

About us   |   Why use us?   |   Reviews   |   Press   |   Contact us   Copyright © 2005-2007 www.factbites.com Usage implies agreement with terms.