Journal ArticleDOI
Ambiguity in context free languages
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It is shown that no language contained in w, each of which contains w, is inherently ambiguous, and a necessary and sufficient algebraic condition is given for a bounded language to be inherently ambiguous.Abstract:
Four principal results about ambiguity in languages (i.e., context free languages) are proved. It is first shown that the problem of determining whether an arbitrary language is inherently ambiguous is recursively unsolvable. Then a decision procedure is presented for determining whether an arbitrary bounded grammar is ambiguous. Next, a necessary and sufficient algebraic condition is given for a bounded language to be inherently ambiguous. Finally, it is shown that no language contained in w1*w2*, each w1 a word, is inherently ambiguous.read more
Citations
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Dissertation
Approximating Context-Free Grammars for Parsing and Verification
TL;DR: The grammar approximation technique discussed in the thesis is applied to nondeterminism and ambiguity issues in two different ways, one for the generation of noncanonical parsers, and the other for ambiguity detection in itself, with the insurance that a grammar reported as unambiguous is actually so.
Journal ArticleDOI
Bond-free DNA language classes
TL;DR: This paper develops new unary operators on languages for characterizing bond-free properties exactly, using familiar code-theoretic equations and focuses on relationships to classes of languages from the theory of codes.
Book ChapterDOI
Parsing as a subtask of compiling
Jaroslav Král,Jiří Demner +1 more
TL;DR: In the last years the research of context-free languages was concentrated on the problems of syntactic analysis and recently on the problem of the integrated theory of parsing and compiling using affix or attribute grammars.
Book ChapterDOI
Graph-Controlled Systems — An Extension of OL systems
TL;DR: In a study of Lindenmayer developmental systems tabled OL systems has been investigated to examine the influence of changing environments on the growth of biological organism, and it is observed that none of them try to give variety to tables themselves rather than the use of the tables.
Journal ArticleDOI
On bounded languages and reversal-bounded automata
Oscar H. Ibarra,Bala Ravikumar +1 more
TL;DR: A new (simpler) proof that every context-free language L ?
References
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Journal ArticleDOI
Three models for the description of language
TL;DR: It is found that no finite-state Markov process that produces symbols with transition from state to state can serve as an English grammar, and the particular subclass of such processes that produce n -order statistical approximations to English do not come closer, with increasing n, to matching the output of anEnglish grammar.
Journal ArticleDOI
Finite automata and their decision problems
Michael O. Rabin,Dana Scott +1 more
TL;DR: Finite automata are considered as instruments for classifying finite tapes as well as generalizations of the notion of an automaton are introduced and their relation to the classical automata is determined.
Journal ArticleDOI
On certain formal properties of grammars
Noam Chomsky,Noam Chomsky +1 more
TL;DR: A sequence of restrictions that limit grammars first to Turing machines, then to two types of system from which a phrase structure description of the generated language can be drawn, and finally to finite state Markov sources are shown to be increasingly heavy.
Book ChapterDOI
The Algebraic Theory of Context-Free Languages*
TL;DR: This chapter discusses the several classes of sentence-generating devices that are closely related, in various ways, to the grammars of both natural languages and artificial languages of various kinds.
Journal ArticleDOI
A variant of a recursively unsolvable problem
TL;DR: In this article, the correspondence decision problem is defined as the problem of determining for an arbitrary finite set (gu g{), (g2, g2), • • •, (gM, gi) of pairs of corresponding non-null strings on a, b whether there is a solution in w, iu ii, • •• •, in of equation