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Context-Free Grammars

2011
In the compilation of source programs, the second phase of the process is the syntactical analysis. Based on the lexical analysis, the syntactical analysis checks the correctness of the source programs in terms of the grammar of the language used. And it is well-known that most of the properties of the programming languages are context-free. Therefore,
Yunlin Su, Song Y. Yan
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Context-Free Categorical Grammars

2009
We define generic categorical notions of rewriting and grammar, using two basic operations, pullback and pushout, and show that these categorical grammars are intrinsically context-free in the sense of Courcelle. We then specialise to various settings, including classical word grammars, hyperedge replacement grammars or node-replacement grammars.
Ly, Olivier, Bauderon, Michel, Chen, Rui
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Context-Free Grammar

1984
A context-free grammar is a collection of context-free phrase structure rules. Each such rule names a constituent type and specifies a possible expansion thereof. The standard notation is: $$ {\rm{lhs}}\,\, \to \,\,{\rm{rh}}{{\rm{s}}_{\rm{1}}}\,\,.\,\,.\,\,.\,\,{\rm{rh}}{{\rm{s}}_{\rm{n}}} $$ where lhs names the constituent, and rhs1 through ...
Lincoln Wallen, Alan Bundy
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Predictors of Context-Free Grammars

SIAM Journal on Computing, 1980
A predictor of a context-free grammar G is a substring of a sentence in $L(G)$ which determines unambiguously the contents of the parse stack immediately before (in top-down parsing) or after (in bottom-up parsing) symbols of the predictor are processed.
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Indexed Grammars—An Extension of Context-Free Grammars

Journal of the ACM, 1967
A new type of grammar for generating formal languages, called an indexed grammar, is presented. An indexed grammar is an extension of a context-free grammar, and the class of languages generated by indexed grammars has closure properties and decidability results similar to those for context-free languages.
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Context-Free Grammars and XML Languages

2006
We 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
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On a Construction of Context-free Grammars

Fundamenta Informaticae, 2000
The grammatical inference problem is solved for the class of context-free languages. A context-free language is supposed to be given by means of all its strings. Considering all strings of length bounded by k, context-free grammars G_{j,k} with 1≤j<k are constructed. A~continual increasing of the index~$k$ leads to an~infinite sequence (G_{j,k})_{j&
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Context-Free Grammars

1993
Context-free grammars are a language for defining languages. Not all languages can be defined by a context-free grammar — only the (yes) context-free ones. Suppose we want to define the language of a small child, who continually says sentences like “want cookie”. His or her sentences consist of a verb followed by a noun.
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Context-Free Grammars and Languages

1977
You may have seen something like the following used to give a formal defini-tion of a language. This notation is sometimes called BNF for Backus-Naur form.
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