Introduction to local certification

TL;DR

This paper introduces local certification in distributed graph algorithms, explaining how labels can verify correct configurations efficiently, and reviews its history, techniques, and research directions.

Contribution

It provides an overview of local certification, highlighting its significance, methods, and recent research developments in distributed verification.

Findings

Local certification enables efficient verification of network configurations.

Various techniques and models are used in local certification.

Research in this area is active with evolving methods.

Abstract

A distributed graph algorithm is basically an algorithm where every node of a graph can look at its neighborhood at some distance in the graph and chose its output. As distributed environment are subject to faults, an important issue is to be able to check that the output is correct, or in general that the network is in proper configuration with respect to some predicate. One would like this checking to be very local, to avoid using too much resources. Unfortunately most predicates cannot be checked this way, and that is where certification comes into play. Local certification (also known as proof-labeling schemes, locally checkable proofs or distributed verification) consists in assigning labels to the nodes, that certify that the configuration is correct. There are several point of view on this topic: it can be seen as a part of self-stabilizing algorithms, as labeling problem, or as a non-deterministic distributed decision. This paper is an introduction to the domain of local certification, giving an overview of the history, the techniques and the current research directions.