Shotgun assembly of random regular graphs

Elchanan Mossel, Nike Sun

Published 2015-12-28Version 1

In recent work, Mossel and Ross (2015) consider the shotgun assembly problem for random graphs G: what radius R ensures that G can be uniquely recovered from its list of rooted R-neighborhoods, with high probability? Here we consider this question for random regular graphs of fixed degree d (at least three). A result of Bollobas (1982) implies efficient recovery at $R=((1+\epsilon)\log n)/(2\log(d-1))$ with high probability --- moreover, this recovery algorithm uses only a summary of the distances in each neighborhood. We show that using the full neighborhood structure gives a sharper bound $R = (\log n + \log\log n)/(2\log(d-1))+ O(1)$, which we prove is tight up to the O(1) term. One consequence of our proof is that if G,H are independent graphs where G follows the random regular law, then with high probability the graphs are non-isomorphic; and this can be efficiently certified by testing the R-neighborhood list of H against the R-neighborhood of a single adversarially chosen vertex of G.