Deterministic Massively Parallel Connectivity

Abstract: We consider the problem of designing fundamental graph algorithms on the model of Massive Parallel Computation (MPC). The input to the problem is an undirected graph $G$ with $n$ vertices and $m$ edges, and with $D$ being the maximum diameter of any connected component in $G$. We consider the MPC with low local space, allowing each machine to store only $\Theta(n<sup>\delta)$ words for an arbitrarily constant $\delta &gt; 0$, and with linear global space (which is equal to the number of machines times the local space available), that is, with optimal utilization. In a recent breakthrough, Andoni et al. (FOCS 18) and Behnezhad et al. (FOCS 19) designed parallel randomized algorithms that in $O(\log D + \log \log n)$ rounds on an MPC with low local space determine all connected components of an input graph, improving upon the classic bound of $O(\log n)$ derived from earlier works on PRAM algorithms. In this paper, we show that asymptotically identical bounds can be also achieved for deterministic algorithms: we present a deterministic MPC low local space algorithm that in $O(\log D + \log \log n)$ rounds determines all connected components of the input graph.