TY - JOUR

T1 - Two-sided context specifications in formal grammars

AU - Barash, Mikhail

AU - Okhotin, Alexander

PY - 2015/8/2

Y1 - 2015/8/2

N2 - In a recent paper (M. Barash, A. Okhotin, "An extension of context-free grammars with one-sided context specifications", Inform. and Comput., 2014), the authors introduced an extension of the context-free grammars equipped with an operator for referring to the left context of the substring being defined. This paper proposes a more general model, in which context specifications may be two-sided, that is, both the left and the right contexts can be specified by the corresponding operators. The paper gives the definitions, presents several examples of grammars and establishes a basic normal form theorem. This normal form, in particular, leads to a simple parsing algorithm working in time O(n4), where n is the length of the input string.

AB - In a recent paper (M. Barash, A. Okhotin, "An extension of context-free grammars with one-sided context specifications", Inform. and Comput., 2014), the authors introduced an extension of the context-free grammars equipped with an operator for referring to the left context of the substring being defined. This paper proposes a more general model, in which context specifications may be two-sided, that is, both the left and the right contexts can be specified by the corresponding operators. The paper gives the definitions, presents several examples of grammars and establishes a basic normal form theorem. This normal form, in particular, leads to a simple parsing algorithm working in time O(n4), where n is the length of the input string.

KW - Conjunctive grammars

KW - Context-free grammars

KW - Context-sensitive grammars

KW - Grammars with contexts

KW - Parsing

UR - http://www.scopus.com/inward/record.url?scp=84943659952&partnerID=8YFLogxK

U2 - 10.1016/j.tcs.2015.05.004

DO - 10.1016/j.tcs.2015.05.004

M3 - Article

AN - SCOPUS:84943659952

VL - 591

SP - 134

EP - 153

JO - Theoretical Computer Science

JF - Theoretical Computer Science

SN - 0304-3975

ER -