Results 241 to 250 of about 767,182 (284)
Some of the next articles are maybe not open access.
1988
In this chapter we shall define a class of rewriting systems called context-free grammars. The left-hand side of a rule in a context-free grammar consists of a single symbol, so that symbols are rewritten “context-freely”. Context-free grammars are of central importance to us because they define the class of context-free languages, the parsing of which
Seppo Sippu, Eljas Soisalon-Soininen
openaire +1 more source
In this chapter we shall define a class of rewriting systems called context-free grammars. The left-hand side of a rule in a context-free grammar consists of a single symbol, so that symbols are rewritten “context-freely”. Context-free grammars are of central importance to us because they define the class of context-free languages, the parsing of which
Seppo Sippu, Eljas Soisalon-Soininen
openaire +1 more source
2004
Context-free grammars and languages play an important role in Linguistics and Computer Science. Introduced by Noam Chomsky in 1958 as tools for the description of natural language, it was soon realized that they also could be used for the design of programming languages.
openaire +1 more source
Context-free grammars and languages play an important role in Linguistics and Computer Science. Introduced by Noam Chomsky in 1958 as tools for the description of natural language, it was soon realized that they also could be used for the design of programming languages.
openaire +1 more source
Kernels of Context-Free Languages
International Journal of Foundations of Computer ScienceWhile the closure of a language family [Formula: see text] under certain language operations is the least family of languages which contains all members of [Formula: see text] and is closed under all of the operations, a kernel of [Formula: see text] is a maximal family of languages which is a sub-family of [Formula: see text] and is closed under all ...
Martin Kutrib, Luca Prigioniero
openaire +2 more sources
The Hardest Context-Free Language
SIAM Journal on Computing, 1973There is a context-free language $L_0 $ such that every context-free language is an inverse homomorphic image of $L_0 $ or $L_0 - \{ e\} $. Hence the time complexity of recognition of $L_0 $ is the least upper bound for time complexity of recognition of context-free languages. A similar result holds for quasirealtime Turing machine languages.
openaire +1 more source
On Universally Polynomial Context-Free Languages
International Journal of Foundations of Computer Science, 2001A language is universally polynomial if its intersection with every NP-complete language is in P. Such a language would provide an automatic method for generating easy instances of intractable problems. In this note, we give a complete characterization of universally polynomial languages that are context-free, answering an open question in [4].
openaire +1 more source
2011
Among what are called languages, there are artificial languages such as programming languages and natural languages such as English, German, French, and Japanese, etc. The languages that we study in this book belong to the former group, and in this chapter we study context-free languages in the former group.
openaire +1 more source
Among what are called languages, there are artificial languages such as programming languages and natural languages such as English, German, French, and Japanese, etc. The languages that we study in this book belong to the former group, and in this chapter we study context-free languages in the former group.
openaire +1 more source
Context-Free Grammars and XML Languages
2006We study the decision properties of XML languages. It was known that given a context-free language included in the Dyck language with sufficiently many pairs of parentheses, it is undecidable whether or not it is an XML language. We improve on this result by showing that the problem remains undecidable when the language is written on a unique pair of ...
A. Bertoni, C. Choffrut, B. Palano
openaire +3 more sources
Noncounting Context-Free Languages
Journal of the ACM, 1978CRESPI REGHIZZI, STEFANO +2 more
openaire +4 more sources
2007
In this paper, I present the class of linear context free languages (LCFLs) with a class of non-deterministic one-way two-head (read only) automata, called non-deterministic linear automata (NLA). At the begining of the work of an NLA, the reading heads are installed under the opposite ends of the given input string.
openaire +1 more source
In this paper, I present the class of linear context free languages (LCFLs) with a class of non-deterministic one-way two-head (read only) automata, called non-deterministic linear automata (NLA). At the begining of the work of an NLA, the reading heads are installed under the opposite ends of the given input string.
openaire +1 more source