scholarly journals Binary Context-Free Grammars

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1209
Author(s):  
Sherzod Turaev ◽  
Rawad Abdulghafor ◽  
Ali Amer Alwan ◽  
Ali Abd Almisreb ◽  
Yonis Gulzar
Keyword(s):  
Binary Relation ◽  
Production Rules ◽  
Relational Grammar ◽  
Generate Matrix ◽  
Context Free ◽  
Context Free Grammars

A binary grammar is a relational grammar with two nonterminal alphabets, two terminal alphabets, a set of pairs of productions and the pair of the initial nonterminals that generates the binary relation, i.e., the set of pairs of strings over the terminal alphabets. This paper investigates the binary context-free grammars as mutually controlled grammars: two context-free grammars generate strings imposing restrictions on selecting production rules to be applied in derivations. The paper shows that binary context-free grammars can generate matrix languages whereas binary regular and linear grammars have the same power as Chomskyan regular and linear grammars.

scholarly journals Representing and Learning Grammars in Answer Set Programming

2019 ◽  
Vol 33 ◽  
pp. 2919-2928 ◽  
Author(s):  
Mark Law ◽  
Alessandra Russo ◽  
Elisa Bertino ◽  
Krysia Broda ◽  
Jorge Lobo
Keyword(s):  
Answer Set Programming ◽  
Learning Task ◽  
Decision Problems ◽  
Production Rules ◽  
Prototype Implementation ◽  
Context Sensitive ◽  
Context Free ◽  
Context Free Grammars ◽  
Answer Set

In this paper we introduce an extension of context-free grammars called answer set grammars (ASGs). These grammars allow annotations on production rules, written in the language of Answer Set Programming (ASP), which can express context-sensitive constraints. We investigate the complexity of various classes of ASG with respect to two decision problems: deciding whether a given string belongs to the language of an ASG and deciding whether the language of an ASG is non-empty. Specifically, we show that the complexity of these decision problems can be lowered by restricting the subset of the ASP language used in the annotations. To aid the applicability of these grammars to computational problems that require context-sensitive parsers for partially known languages, we propose a learning task for inducing the annotations of an ASG. We characterise the complexity of this task and present an algorithm for solving it. An evaluation of a (prototype) implementation is also discussed.

Context-Free Grammars

2016 ◽  
pp. 159-178
Author(s):  
Wolfgang J. Paul ◽  
Christoph Baumann ◽  
Petro Lutsyk ◽  
Sabine Schmaltz
Keyword(s):  
Context Free ◽  
Context Free Grammars
Sign in / Sign up

Export Citation Format

Share Document