Next Article in Journal
Optimization-Based Approaches to Control of Probabilistic Boolean Networks
Next Article in Special Issue
Adaptive Vector Quantization for Lossy Compression of Image Sequences
Previous Article in Journal
Stable Analysis of Compressive Principal Component Pursuit
Previous Article in Special Issue
Concurrent vs. Exclusive Reading in Parallel Decoding of LZ-Compressed Files
Article Menu

Export Article

Open AccessArticle
Algorithms 2017, 10(1), 30; doi:10.3390/a10010030

Towards Efficient Positional Inverted Index †

1
Department of Theoretical Computer Science, Faculty of Information Technology, Czech Technical University in Prague, Prague 16000, Czech Republic
2
Current address: Thákurova 2700/9, 16000 Praha 6, Czech Republic.
*
Author to whom correspondence should be addressed.
Academic Editor: Bruno Carpentieri
Received: 23 December 2016 / Revised: 7 February 2017 / Accepted: 17 February 2017 / Published: 22 February 2017
(This article belongs to the Special Issue Data Compression, Communication Processing and Security 2016)
View Full-Text   |   Download PDF [1014 KB, uploaded 22 February 2017]   |  

Abstract

We address the problem of positional indexing in the natural language domain. The positional inverted index contains the information of the word positions. Thus, it is able to recover the original text file, which implies that it is not necessary to store the original file. Our Positional Inverted Self-Index (PISI) stores the word position gaps encoded by variable byte code. Inverted lists of single terms are combined into one inverted list that represents the backbone of the text file since it stores the sequence of the indexed words of the original file. The inverted list is synchronized with a presentation layer that stores separators, stop words, as well as variants of the indexed words. The Huffman coding is used to encode the presentation layer. The space complexity of the PISI inverted list is O ( ( N n ) log 2 b N + ( N n α + n ) × ( log 2 b n + 1 ) ) where N is a number of stems, n is a number of unique stems, α is a step/period of the back pointers in the inverted list and b is the size of the word of computer memory given in bits. The space complexity of the presentation layer is O ( i = 1 N log 2 p i n ( i ) j = 1 N log 2 p j + N ) with respect to p i n ( i ) as a probability of a stem variant at position i, p j as the probability of separator or stop word at position j and N as the number of separators and stop words. View Full-Text
Keywords: inverted index; search engines; self-indexing; natural language processing; data compression inverted index; search engines; self-indexing; natural language processing; data compression
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Procházka, P.; Holub, J. Towards Efficient Positional Inverted Index †. Algorithms 2017, 10, 30.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Algorithms EISSN 1999-4893 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top