Approximate Proof-Labeling Schemes

  • Keren Censor-HillelEmail author
  • Ami Paz
  • Mor Perry
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10641)


We study a new model of verification of boolean predicates over distributed networks. Given a network configuration, the proof-labeling scheme (PLS) model defines a distributed proof in the form of a label that is given to each node, and all nodes locally verify that the network configuration satisfies the desired boolean predicate by exchanging labels with their neighbors. The proof size of the scheme is defined to be the maximum size of a label.

In this work, we extend this model by defining the approximate proof-labeling scheme (APLS) model. In this new model, the predicates for verification are of the form \(\psi \le \varphi \), where \(\psi , \varphi : \mathcal{F}\rightarrow \mathbb {N}\) for a family of configurations \(\mathcal{F}\). Informally, the predicates considered in this model are a comparison between two values of the configuration. As in the PLS model, nodes exchange labels in order to locally verify the predicate, and all must accept if the network satisfies the predicate. The soundness condition is relaxed with an approximation ration \(\alpha \), so that only if \(\psi > \alpha \varphi \) some node must reject.

We show that in the APLS model, the proof size can be much smaller than the proof size of the same predicate in the PLS model. Moreover, we prove that there is a tradeoff between the approximation ratio and the proof size.


Distributed graph algorithms Distributed verification Approximation algorithms Primal-dual algorithms 



We thank Gilad Kutiel, Seffi Naor and Dror Rawitz for discussions of the primal-dual method, and the anonymous reviewers of SIROCCO 2017 for valuable comments.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Department of Computer ScienceTechnionHaifaIsrael
  2. 2.Department of Electrical EngineeringTel Aviv UniversityTel AvivIsrael

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