Fast Approximate Shortest Paths in the Congested Clique

We design fast deterministic algorithms for distance computation in the Congested CLIQE model. Our key contributions include: center dot A (2 + epsilon)-approximation for all-pairs shortest paths problem in O(log(2) n/epsilon) rounds on unweighted undirected graphs. With a small additional additive factor, this also applies for weighted graphs. This is the first sub-polynomial constantfactor approximation for APSP in this model. center dot A (1+ epsilon)-approximation for multi-source shortest paths problem from O(root n) sources in O(log(2) n/epsilon) rounds on weighted undirected graphs. This is the first sub-polynomial algorithm obtaining this approximation for a set of sources of polynomial size. Our main techniques are new distance tools that are obtained via improved algorithms for sparse matrix multiplication, which we leverage to construct efficient hopsets and shortest paths. Furthermore, our techniques extend to additional distance problems for which we improve upon the state-of-the-art, including diameter approximation, and an exact single-source shortest paths algorithm for weighted undirected graphs in (O) over tilde (n(1/6)) rounds.