On distributed merlin-arthur decision protocols

Pierre Fraigniaud, Pedro Montealegre, Rotem Oshman, Ivan Rapaport, Ioan Todinca

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

9 Scopus citations


In a distributed locally-checkable proof, we are interested in checking the legality of a given network configuration with respect to some Boolean predicate. To do so, the network enlists the help of a prover—a computationally-unbounded oracle that aims at convincing the network that its state is legal, by providing the nodes with certificates that form a distributed proof of legality. The nodes then verify the proof by examining their certificate, their local neighborhood and the certificates of their neighbors. In this paper we examine the power of a randomized form of locally-checkable proof, called distributed Merlin-Arthur protocols, or dMA for short. In a dMA protocol, the prover assigns each node a short certificate, and the nodes then exchange random messages with their neighbors. We show that while there exist problems for which dMA protocols are more efficient than protocols that do not use randomness, for several natural problems, including Leader Election, Diameter, Symmetry, and Counting Distinct Elements, dMA protocols are no more efficient than standard nondeterministic protocols. This is in contrast with Arthur-Merlin (dMA) protocols and Randomized Proof Labeling Schemes (RPLS), which are known to provide improvements in certificate size, at least for some of the aforementioned properties.

Original languageEnglish
Title of host publicationStructural Information and Communication Complexity - 26th International Colloquium, SIROCCO 2019, Proceedings
EditorsKeren Censor-Hillel, Michele Flammini
PublisherSpringer Verlag
Number of pages16
ISBN (Print)9783030249212
StatePublished - 2019
Externally publishedYes
Event26th International Colloquium on Structural Information and Communication Complexity, SIROCCO 2019 - L'Aquila, Italy
Duration: 1 Jul 20194 Jul 2019

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11639 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference26th International Colloquium on Structural Information and Communication Complexity, SIROCCO 2019


  • Distributed verification
  • Interactive computation
  • Interactive proof systems
  • Nondeterminism


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