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Structural similarity in context-free languages

Meera Blattner
1976 Information and Control  
Divide the context-free languages into equivalence classes in the following way: L1 and L2 are in the same class if there are a-transducers M and M such that M(L1) ~ L~ and d~r(L,) = L1.  ...  Define L1 and L~ to be structurally similar if they are in the same class.  ...  ACKNOWLEDGMENT Much of the material found in this paper is from my dissertation. I am deeply grateful to my advisor, Professor Sheila Greibach, for her guidance.  ... 
doi:10.1016/s0019-9958(76)90518-0 fatcat:j57mltfnmjarxkajxdphoa5xyi

Page 2255 of Mathematical Reviews Vol. 52, Issue 6 [page]

1976 Mathematical Reviews  
{For the entire collection see MR 52 #7755.} 16134 Blattner, Meera 16135 Structural similarity in context-free languages. Information and Control 30 (1976), no. 3, 267-294.  ...  The author considers when a language L is structurally similar to the set of sentential forms of some (context-free) grammar.  ... 

Page 260 of Computational Linguistics Vol. 15, Issue 4 [page]

1989 Computational Linguistics  
The RPDA languages do not, as yet, have a grammar characterization similar to that of context-free grammar, but the RCFG grammars are context-free like grammars that do capture at least a large subclass  ...  Postal, Paul 1964 Limitations of Phrase Structure Grammars. In: Fodor, J.A.; and Katz, J.J. (eds.), The Structure of Language: Readings in the Philosophy of Language.  ... 

Schwyzertuutsch, Bambara, and Context-Free Languages

2020 Studia Semiotyczne  
While restraining from siding with any answer to the problem, Chomsky sparked a long philosophical and linguistic discussion revolving around complex structures in natural languages.  ...  The author himself claimed the theory applied exclusively to formal languages, but in his considerations he also happened to formulate a problem relating to natural languages, namely, to which formal grammar  ...  ) . xxand similar languages are often used to demonstrate that some language phenomena are not context-free.  ... 
doaj:03d75ea799d8411aaf3d1a86368b79b8 fatcat:nyyir73w35h6bgexb7jce562rm

Page 1460 of Mathematical Reviews Vol. 46, Issue 5 [page]

1973 Mathematical Reviews  
It is well known that every context-free language can be expressed in terms of the solution to a set of equations.  ...  An addi- tional consequence is that some context-free languages cannot be generated from any set of bounded context-free languages by full AFL operations and substitution.”  ... 

Page 4901 of Mathematical Reviews Vol. , Issue 82k [page]

1982 Mathematical Reviews  
The author proves that any context-free language generated by a given context-free grammar determines a word context-free algebra as the natural structure of this language.  ...  This context-free algebra is specified by a finite basis and determines a similarity class of algebraic structures.  ... 

Page 306 of Computational Linguistics Vol. 27, Issue 2 [page]

2001 Computational Linguistics  
Thus it does in a sense show a certain GB theory to be strongly context-free (p. 6).  ...  had weakly context-free recognizing power.)  ... 

Recent Progresses in the Linguistic Modeling of Biological Sequences Based on Formal Language Theory

Hyun-Seok Park, Bulgan Galbadrakh, Young-Mi Kim
2011 Genomics & Informatics  
Grammars used in this way would constitute a model of underlying biological processes or structures, and that grammars may, in fact, serve as an appropriate tool for theory formation.  ...  Treating genomes just as languages raises the possibility of producing concise generalizations about information in biological sequences.  ...  In the Chomsky hierarchy in Fig. 2 , type-2 grammar, or context-free grammar generates context-free language, which is more powerful than regular grammar.  ... 
doi:10.5808/gi.2011.9.1.005 fatcat:5xcv4fhfh5bu3cedb7dhexabfm

Schema extraction from XML collections

Boris Chidlovskii
2002 Proceedings of the second ACM/IEEE-CS joint conference on Digital libraries - JCDL '02  
We model the XML schema as extended context-free grammars and develop a novel extraction algorithm inspired by methods of grammatical inference.  ...  XML Schema language has been proposed to replace Document Type Definitions (DTDs) as schema mechanism for XML data.  ...  Induce an extended context-free grammar we represent XML documents as a structured example of an (unknown) ECFG, where structured examples are derivation trees of a CFG with all nonterminal labels removed  ... 
doi:10.1145/544283.544288 fatcat:2byvwa4cafb2jbvhklmi2w2wfm

Schema extraction from XML collections

Boris Chidlovskii
2002 Proceedings of the second ACM/IEEE-CS joint conference on Digital libraries - JCDL '02  
We model the XML schema as extended context-free grammars and develop a novel extraction algorithm inspired by methods of grammatical inference.  ...  XML Schema language has been proposed to replace Document Type Definitions (DTDs) as schema mechanism for XML data.  ...  Induce an extended context-free grammar we represent XML documents as a structured example of an (unknown) ECFG, where structured examples are derivation trees of a CFG with all nonterminal labels removed  ... 
doi:10.1145/544220.544288 dblp:conf/jcdl/Chidlovskii02 fatcat:zuxrlzkpvbegjd6uowdjr6ajmm

Page 1877 of Mathematical Reviews Vol. 55, Issue 6 [page]

1978 Mathematical Reviews  
In a similar way, parametric grammars of recursive type are defined. They are proved to generate all context-free languages.  ...  Standard results on context-free grammars are proved, e.g., any e-free context-free language can be generated by a suitable e-free context-free grammar.  ... 

On differentiation functions, structure functions, and related languages of context-free grammars

Jürgen Dassow, Victor Mitrana, Gheorghe Păun, Ralf Stiebe
2004 RAIRO - Theoretical Informatics and Applications  
We introduce the notion of a differentiation function of a context-free grammar which gives the number of terminal words that can be derived in a certain number of steps.  ...  We discuss the decidability of the equivalence of grammars with respect to the differentiation function and structure function and prove the decidability of the k-narrowness of context-free grammars.  ...  This function is nearly related to the structure function of context-free languages which gives the number of words of a certain length in the language.  ... 
doi:10.1051/ita:2004013 fatcat:lmb5bpsctzbffn36gmwy65doqu

Evolving Memory Cell Structures for Sequence Learning [chapter]

Justin Bayer, Daan Wierstra, Julian Togelius, Jürgen Schmidhuber
2009 Lecture Notes in Computer Science  
The fitness function reflects the structure's usefulness for learning various formal languages. The evolved cells help to understand crucial structural features that aid sequence learning.  ...  The most popular cell structure seems somewhat arbitrary though. Here we optimize its topology with a multi-objective evolutionary algorithm.  ...  Context-free and Context-sensitive Languages Context-free languages are languages that can be recognized by a non-deterministic push-down automaton.  ... 
doi:10.1007/978-3-642-04277-5_76 fatcat:kixbqu4e2zeb3b5vn2dyptbmlu

Page 1341 of Mathematical Reviews Vol. 51, Issue 4 [page]

1976 Mathematical Reviews  
but cannot be covered by any finite number of rigid context-free languages.  ...  In the case in which a phrase structure grammar G is context-free a derivation word corresponding to a word in L(G) becomes the prefix repre- sentation of a derivation tree together with rule names.  ... 

Page 746 of Mathematical Reviews Vol. 38, Issue 4 [page]

1969 Mathematical Reviews  
In this paper, the author gives a construction that asso- ciates Turing machines and context-free languages.  ...  Theorem: Given an AFL J, the family of all sets of the form L(G), where C is in # and G is a phrase structure gram- mar (context-free grammar), is a full AFL.  ... 
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