TY - GEN
T1 - Defining contexts in context-free grammars
AU - Barash, Mikhail
AU - Okhotin, Alexander
PY - 2012/3/12
Y1 - 2012/3/12
N2 - Conjunctive grammars (Okhotin, 2001) are an extension of the standard context-free grammars with a conjunction operation, which maintains most of their practical properties, including many parsing algorithms. This paper introduces a further extension to the model, which is equipped with quantifiers for referring to the left context, in which the substring being defined does occur. For example, a rule A → a & ◁B defines a string a, as long as it is preceded by any string defined by B. The paper gives two equivalent definitions of the model-by logical deduction and by language equations-and establishes its basic properties, including a transformation to a normal form, a cubic-time parsing algorithm, and another recognition algorithm working in linear space.
AB - Conjunctive grammars (Okhotin, 2001) are an extension of the standard context-free grammars with a conjunction operation, which maintains most of their practical properties, including many parsing algorithms. This paper introduces a further extension to the model, which is equipped with quantifiers for referring to the left context, in which the substring being defined does occur. For example, a rule A → a & ◁B defines a string a, as long as it is preceded by any string defined by B. The paper gives two equivalent definitions of the model-by logical deduction and by language equations-and establishes its basic properties, including a transformation to a normal form, a cubic-time parsing algorithm, and another recognition algorithm working in linear space.
UR - http://www.scopus.com/inward/record.url?scp=84857809563&partnerID=8YFLogxK
U2 - 10.1007/978-3-642-28332-1_10
DO - 10.1007/978-3-642-28332-1_10
M3 - Conference contribution
AN - SCOPUS:84857809563
SN - 9783642283314
T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
SP - 106
EP - 118
BT - Language and Automata Theory and Applications - 6th International Conference, LATA 2012, Proceedings
T2 - 6th International Conference on Language and Automata Theory and Applications, LATA 2012
Y2 - 5 March 2012 through 9 March 2012
ER -