Showing papers on "Indexed language published in 1977"
TL;DR: It is shown that the following families of languages can be recognized by deterministic multitape Turing machines either in polynomial time or within (log n)2 tape: the context independent developmental (EOL) languages; the simple matrix languages; and the languages generated by derivation restricted state grammars.
Abstract: The time and tape complexity of some families of languages defined in the literature by altering methods of generation by context-free grammars is considered. Specifically; it is shown that the following families of languages can be recognized by deterministic multitape Turing machines either in polynomial time or within (log n)2 tape: 1) the context independent developmental (EOL) languages; 2) the simple matrix languages; 3) the languages generated by derivation restricted state grammars.: 4) the languages generated by linear context-free grammars with certain non-regular control sets; 5) the languages generated by certain classes of vector grammars. In fact, these languages are of the same tape complexity as context-free languages. Other results indicate the complexity of EDOL languages and the effects on complexity of applying the homomorphic replication operator to regular and context-free languages.
32 citations
TL;DR: It is shown that many common normal forms (e. g. Greibach normal form) cannot be obtained for TC grammars in general, and a context-free generator for all type 0 languages is exhibited.
Abstract: Languages are studied which can be generated by context-free grammars under a single simple restriction which must be satisfied by its derivation trees. Using tree controlled grammars (TC grammars for short) all unambigous and some inherently ambigous context-free languages, and also some non context-free languages can be parsed in timeO(n2). The classes of regular, linear, context-free, EOL, ETOL and type 0 languages can be characterized in a natural manner using TC grammars. A context-free generator for all type 0 languages is exhibited. Some normal forms for TC grammars are established but it is shown that many common normal forms (e. g. Greibach normal form) cannot be obtained for TC grammars in general.
22 citations
18 Jul 1977
TL;DR: For each nondeterministie successor RAM, the derivation language is contained in TIME and its complement in NTIME and the following holds:.
Abstract: 3. For each nondeterministie successor RAM (we define this machine in such a way that it can guess in one step the content of an arbitrary register) the derivation language is contained in TIME (n • log n) and its complement in NTIME (~ . Especially for the time complexity classes NRAM (..) defined by this machine and for the time complexity classes Nk DIM (..) defined by nondeterministic k-dimensional Turing machines the following holds:
13 citations
TL;DR: It is proved that the class of polynomial measurable languages is a Pre-AFL, which is a special case of the general notion.
Abstract: In this paper we introduce a class of measures on formal languages. These measures are based on the number of different ways a string of a specified finite length can be completed to obtain strings of the language. The relation with automata and grammars is established, and the polynomial measure, a special case of the general notion, is studied in detail. We give some closure properties for well-known operations on languages, and finally, we prove that the class of polynomial measurable languages is a Pre-AFL.
7 citations
TL;DR: It is shown that, given a right linear or a strongLL(k) grammar, it is possible to produce automatically a pointer Markov algorithm parsing the language generated by the grammar.
Abstract: Markov algorithms have received very little attention in the studies about formal languages, so the purpose of the present paper is twofold: i) to characterize languages in terms of Markov algorithms, and ii) to produce automatically Markov algorithms accepting or parsing languages generated by given grammars.
2 citations
TL;DR: The degree and order induce infinite proper hierarchies on the classes of coupled languages and translations, which are more powerful than context-free grammars and more than syntax directed translation schemes.
Abstract: A class of formal grammars called coupled grammars are introduced. These are formal generative models for languages as well as translations. As language generating devices these are more powerful than context-free grammars and as translation generating devices these arc more powerful than syntax directed translation schemes. Three parameters of these grammars: degree, order and µ-simplicity are identified, which characterize aspects of their description. The structures induced on coupled languages and translations by restrictions placed on the values of these parameters (of coupled grammars), are studied. Some of the specific results are: the degree and order induce infinite proper hierarchies on the classes of coupled languages and translations.
1 citations