NDLI: Compressing and indexing labeled trees, with applications

Content Provider	ACM Digital Library
Author	Ferragina, Paolo Luccio, Fabrizio Manzini, Giovanni Muthukrishnan, S.
Copyright Year	2009
Abstract	Consider an ordered, static tree $\textit{T}$ where each node has a label from alphabet Σ. Tree $\textit{T}$ may be of arbitrary degree and shape. Our goal is designing a compressed storage scheme of $\textit{T}$ that supports basic $\textit{navigational}$ operations among the immediate neighbors of a node (i.e. parent, $\textit{i}th$ child, or any child with some label,…) as well as more sophisticated $\textit{path}-based$ search operations over its labeled structure. We present a novel approach to this problem by designing what we call the XBW-transform of the tree in the spirit of the well-known Burrows-Wheeler transform for strings [1994]. The XBW-transform uses path-sorting to linearize the labeled tree $\textit{T}$ into $\textit{two}$ coordinated arrays, one capturing the structure and the other the labels. For the first time, by using the properties of the XBW-transform, our compressed indexes go beyond the information-theoretic lower bound, and support navigational and path-search operations over labeled trees within (near-)optimal time bounds and entropy-bounded space. Our XBW-transform is simple and likely to spur new results in the theory of tree compression and indexing, as well as interesting application contexts. As an example, we use the XBW-transform to design and implement a compressed index for XML documents whose compression ratio is significantly better than the one achievable by state-of-the-art tools, and its query time performance is order of magnitudes faster.
Starting Page	1
Ending Page	33
Page Count	33
File Format	PDF
ISSN	00045411
e-ISSN	1557735X
DOI	10.1145/1613676.1613680
Journal	Journal of the ACM (JACM)
Volume Number	57
Issue Number	1
Language	English
Publisher	Association for Computing Machinery (ACM)
Publisher Date	2009-11-01
Publisher Place	New York
Access Restriction	One Nation One Subscription (ONOS)
Subject Keyword	Burrows-Wheeler transform XML compression XML indexing Labeled tree compression Labeled tree indexing Path searching Tree navigation
Content Type	Text
Resource Type	Article
Subject	Hardware and Architecture Information Systems Control and Systems Engineering Artificial Intelligence Software

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

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