Local certification of local properties: tight bounds, trade-offs and new parameters

Nicolas Bousquet, Laurent Feuilloley, S├ębastien Zeitoun.

STACS 2024: 41st International Symposium on Theoretical Aspects of Computer Science
doi: 10.4230/LIPICS.STACS.2024.21


ArXiv version Publisher's open access version


Local certification is a distributed mechanism enabling the nodes of a network to check the correctness of the current configuration, thanks to small pieces of information called certificates. For many classic global properties, like checking the acyclicity of the network, the optimal size of the certificates depends on the size of the network, $n$. In this paper, we focus on properties for which the size of the certificates does not depend on $n$ but on other parameters. We focus on three such important properties and prove tight bounds for all of them. Namely, we prove that the optimal certification size is: $\Theta(\log k)$ for $k$-colorability (and even exactly $\lceil \log k \rceil$ bits in the anonymous model while previous works had only proved a $2$-bit lower bound); $(1/2)\log t+o(\log t)$ for dominating sets at distance $t$ (an unexpected and tighter-than-usual bound) ; and $\Theta(\log \Delta)$ for perfect matching in graphs of maximum degree $\Delta$ (the first non-trivial bound parameterized by $\Delta$). We also prove some surprising upper bounds, for example, certifying the existence of a perfect matching in a planar graph can be done with only two bits. In addition, we explore various specific cases for these properties, in particular improving our understanding of the trade-off between locality of the verification and certificate size.


S├ębastien presented the paper at JGA 2023.