Regular expressions and context-free grammars for picture languages

1997 ◽  
pp. 283-294 ◽  
Author(s):  
Oliver Matz
Keyword(s):  
Regular Expressions ◽  
Picture Languages ◽  
Context Free ◽  
Context Free Grammars

A Variant of Pure Two-Dimensional Context-Free Grammars Generating Picture Languages

2014 ◽  
pp. 123-133 ◽  
Author(s):  
Zbyněk Křivka ◽  
Carlos Martín-Vide ◽  
Alexander Meduna ◽  
K. G. Subramanian
Keyword(s):  
Two Dimensional ◽  
Picture Languages ◽  
Context Free ◽  
Context Free Grammars

Towards an Effective Syntax and a Generator for Deterministic Standard Regular Expressions

2018 ◽  
Vol 62 (9) ◽  
pp. 1322-1341
Author(s):  
Zhiwu Xu ◽  
Ping Lu ◽  
Haiming Chen
Keyword(s):  
Regular Expression ◽  
Xml Schema ◽  
Experimental Results ◽  
Regular Expressions ◽  
Context Free ◽  
Core Part ◽  
Context Free Grammars

Abstract Deterministic regular expressions are a core part of XML Schema and used in other applications. But unlike regular expressions, deterministic regular expressions do not have a simple syntax, instead they are defined in a semantic manner. Moreover, not every regular expression can be rewritten to an equivalent deterministic regular expression. These properties of deterministic regular expressions put a burden on the user to develop XML Schema Definitions and to use deterministic regular expressions. In this paper, we propose a syntax for deterministic standard regular expressions (DREGs), and prove that the syntax of DREGs is context-free. Based on the context-free grammars for DREGs, we further design a generator for DREGs, which can generate DREGs randomly, and be used in applications associated with DREGs, e.g. benchmarking a validator for DTD or XML Schema, and inclusion checking of DTD and XML Schema. Experimental results demonstrate the efficiency and usefulness of the generator.

Lower bounds for context-free grammars

2011 ◽  
Vol 111 (18) ◽  
pp. 895-898 ◽  
Author(s):  
Yuval Filmus
Keyword(s):  
Lower Bounds ◽  
Context Free ◽  
Context Free Grammars
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