In his seminal work, Kleinberg showed how to augment meshes using random edges, so that they become navigable; that is, greedy routing computes paths of polylogarithmic expected length between any pairs of nodes. This yields the crucial question of determining wether such an augmentation is possible for all
graphs. In this paper, we answer negatively to this question by exhibiting a
threshold on the doubling
dimension, above which an infinite family of
graphs cannot be augmented to become navigable whatever the distribution of random edges is. Precisely, it was known that
graphs of doubling
dimension at most
O(loglog
n) are navigable. We show that for doubling
dimension ?loglog
n, an infinite family of
graphs cannot be augmented to become navigable. Finally, we complete our result by studying the special case of square meshes, that we prove to always be augmentable to become navigable.
Keywords: doubling dimension, small world, greedy routing.