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The power of commuting with finite sets of words
We construct a finite language L such that the largest language commuting with L is not recursively enumerable. This gives a negative answer to the question raised by Conway in 1971 and also strongly disproves Conw...
BA - Obecná matematika
- 2007 •
- Jx
Rok uplatnění
Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
The power of commuting with finite sets of words
We show that one can construct a finite language L such that the largest language commuting with L is not recursively enumerable. This gives a negative answer to the question raised by Conway in 1971 and also stron...
BA - Obecná matematika
- 2005 •
- D
Rok uplatnění
D - Stať ve sborníku
On language inequalities XK ⊆ LX
subset RX} are not recursively enumerable.It is known that for a regular language L and an arbitrary language K the largest solution of the inequality XK subset LX is regular. Here we show that there exist finite ...
BA - Obecná matematika
- 2005 •
- D
Rok uplatnění
D - Stať ve sborníku
The Parallel Generation of Recursively Enumerable Languages Using Only Context-free Productions and Six Nonterminals
This paper defines the notion of an E0L grammar on a free group. The transformation of any type-0 grammar to an equivalent E0L grammar on a free group is demonstrated. Next, an algorithm reducing the number of nonterminals is introduced....
JC - Počítačový hardware a software
- 2005 •
- D
Rok uplatnění
D - Stať ve sborníku
Regulated Pushdown Automata Revisited
This article demonstrates alternative proof of well-known theorem of equivalence between regulated pushdown automata and recursive enumerable languages as shown in Meduna, A., Kolář D.: Regulated Pushdown Automata, Acta Cyb...
JC - Počítačový hardware a software
- 2009 •
- D
Rok uplatnění
D - Stať ve sborníku
Separating the Classes of Recursively Enumerable Languages Based on Machine Size
In the late nineteen sixties it was observed that the r.e. languages form an infinite proper hierarchy based on the size of the Turing machines that accept them. We examine the fundamental position of the finite languages and their ...
IN - Informatika
- 2015 •
- Jx •
- Link
Rok uplatnění
Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
Výsledek na webu
Randomness and Recursive Enumerability
Randomness and Recursive Enumerability...
BA - Obecná matematika
- 2001 •
- Jx
Rok uplatnění
Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
Context-Free Grammars over Free Groups
is demonstrated. As the main result, the equivalence of the family of recursively enumerable languages and the family of languages generated by context-free grammars over free......
JC - Počítačový hardware a software
- 2005 •
- D
Rok uplatnění
D - Stať ve sborníku
Combined Leftmost Derivations in Matrix Grammars
derivation of type three generate the family of recursively enumerable languages.It is an open problem, whether matrix grammars with erasing productions using leftmost derivation of type three generate the whole famil...
JC - Počítačový hardware a software
- 2004 •
- D
Rok uplatnění
D - Stať ve sborníku
How to Generate Recursively Enumerable Languages Using Only Context-free Productions and Eight Nonterminals
The notion of a context-free grammar over a free group is introduced. The transformation of any type-0 grammar to an equivalent context-free grammar over a free group is demonstrated. This approach causes an undesirable increase of the number of nont...
JC - Počítačový hardware a software
- 2005 •
- D
Rok uplatnění
D - Stať ve sborníku
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