On the computational power of shared objects

Gadi Taubenfeld

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


We propose a new classification for evaluating the strength of shared objects. The classification is based on finding, for each object of type o, the strongest progress condition for which it is possible to solve consensus for any number of processes, using any number of objects of type o and atomic registers. We use the strongest progress condition to associate with each object a number call the power number of that object. Objects with higher power numbers are considered stronger. Then, we define the power hierarchy which is an infinite hierarchy of objects such that the objects at level i of the hierarchy are exactly those objects with power number i. Comparing our classification with the traditional one which is based on fixing the progress condition (namely, wait-freedom) and finding the largest number of processes for which consensus is solvable, reveals interesting results. Our equivalence and extended universality results, provide a deeper understanding of the nature of the relative computational power of shared objects.

Original languageEnglish
Title of host publicationPrinciples of Distributed Systems - 13th International Conference, OPODIS 2009, Proceedings
Number of pages15
StatePublished - 2009
Externally publishedYes
Event13th International Conference on Principles of Distributed Systems, OPODIS 2009 - Nimes, France
Duration: 15 Dec 200918 Dec 2009

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume5923 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference13th International Conference on Principles of Distributed Systems, OPODIS 2009


  • Consensus numbers
  • Power hierarchy
  • Power numbers
  • Shared objects
  • Universality
  • Wait-free hierarchy
  • Wait-freedom
  • k-obstruction-freedom


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