Chapter

Combinatorial Algorithms

Volume 6460 of the series Lecture Notes in Computer Science pp 390-403

Dictionary-Symbolwise Flexible Parsing

  • Maxime CrochemoreAffiliated withDept. of Computer Science, King’s College LondonInstitut Gaspard-Monge, Université Paris-Est
  • , Laura GiambrunoAffiliated withDipartimento di Matematica e Informatica, Università di Palermo
  • , Alessio LangiuAffiliated withDipartimento di Matematica e Informatica, Università di PalermoInstitut Gaspard-Monge, Université Paris-Est
  • , Filippo MignosiAffiliated withDipartimento di Informatica, Università dell’Aquila
  • , Antonio RestivoAffiliated withDipartimento di Matematica e Informatica, Università di Palermo

* Final gross prices may vary according to local VAT.

Get Access

Abstract

Linear time optimal parsing algorithms are very rare in the dictionary based branch of the data compression theory. The most recent is the Flexible Parsing algorithm of Mathias and Shainalp that works when the dictionary is prefix closed and the encoding of dictionary pointers has a constant cost. We present the Dictionary − Symbolwise Flexible Parsing algorithm that is optimal for prefix-closed dictionaries and any symbolwise compressor under some natural hypothesis. In the case of LZ78-alike algorithms with variable costs and any, linear as usual, symbolwise compressor can be implemented in linear time. In the case of LZ77-alike dictionaries and any symbolwise compressor it can be implemented in O(n logn) time. We further present some experimental results that show the effectiveness of the dictionary-symbolwise approach.