Labeling schemes for tree representation

Reuven Cohen, Pierre Fraigniaud, David Ilcinkas, Amos Korman, David Peleg

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


This paper deals with compact label-based representations for trees. Consider an n-node undirected connected graph G with a predefined numbering on the ports of each node. The all-ports tree labeling ℒall gives each node v of G a label containing the port numbers of all the tree edges incident to v. The upward tree labeling ℒup labels each node v by the number of the port leading from v to its parent in the tree. Our measure of interest is the worst case and total length of the labels used by the scheme, denoted Mup(T) and Sup(T) for ℒup and Mall(T) and Sall(T) for ℒall. The problem studied in this paper is the following: Given a graph G and a predefined port labeling for it, with the ports of each node v numbered by 0, . . . , deg(v) - 1, select a rooted spanning tree for G minimizing (one of) these measures. We show that the problem is polynomial for Mup(T), Sup(T) and Sall(T) but NP-hard for Mall(T) (even for 3-regular planar graphs). We show that for every graph G and port numbering there exists a spanning tree T for which Sup(T) = O(n log log n). We give a tight bound of O(n) in the cases of complete graphs with arbitrary labeling and arbitrary graphs with symmetric port assignments. We conclude by discussing some applications for our tree representation schemes.

Original languageEnglish
Title of host publicationDistributed Computing - IWDC 2005 - 7th International Workshop, Proceedings
PublisherSpringer Verlag
Number of pages12
ISBN (Print)3540309594, 9783540309598
StatePublished - 2005
Externally publishedYes
Event7th International Workshop on Distributed Computing, IWDC 2005 - Kharagpur, India
Duration: 27 Dec 200530 Dec 2005

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume3741 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference7th International Workshop on Distributed Computing, IWDC 2005

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science


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