Undecidable problems concerning densities of languages

In this paper we prove that the question whether a language presented by a context free grammar has density, is undecidable. Moreover we show that there is no algorithm which, given two unambiguous context free grammars on input, decides whether the language defined by the first grammar has a relati...

Celý popis

Uloženo v:
Podrobná bibliografie
Vydáno v:Discrete mathematics and theoretical computer science Ročník DMTCS Proceedings vol. AF,...; číslo Proceedings; s. 69 - 76
Hlavní autor: Kozik, Jakub
Médium: Journal Article Konferenční příspěvek
Jazyk:angličtina
Vydáno: DMTCS 01.01.2005
Discrete Mathematics and Theoretical Computer Science
Discrete Mathematics & Theoretical Computer Science
Edice:DMTCS Proceedings
Témata:
[info.info-lo] computer science [cs]/logic in computer science [cs.lo]
[info.info-sc] computer science [cs]/symbolic computation [cs.sc]
asymptotic density
Computer Science
context-free languages
decidability
Logic in Computer Science
Symbolic Computation
decidability
context-free languages
asymptotic density
ISSN:1365-8050, 1462-7264, 1365-8050
On-line přístup:Získat plný text
Tagy: Přidat tag
Žádné tagy, Buďte první, kdo vytvoří štítek k tomuto záznamu!
Popis
Shrnutí:In this paper we prove that the question whether a language presented by a context free grammar has density, is undecidable. Moreover we show that there is no algorithm which, given two unambiguous context free grammars on input, decides whether the language defined by the first grammar has a relative density in the language defined by the second one. Our techniques can be extended to show that this problem is undecidable even for languages given by grammars from $LL(k)$ (for sufficiently large fixed $k ∈ \mathbb{N} )$.
ISSN:1365-8050
1462-7264
1365-8050
DOI:10.46298/dmtcs.3471