A Sequential Algorithm for Generating Random Graphs

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Abstract

We present the fastest FPRAS for counting and randomly generating simple graphs with a given degree sequence in a certain range. For degree sequence \((d_i)_{i=1}^n\) with maximum degree \(d_{\max}=O(m^{1/4-\tau})\) , our algorithm generates almost uniform random graph with that degree sequence in time O(m d max ) where is the number of edges in the graph and τ is any positive constant. The fastest known FPRAS for this problem [22] has running time of O(m 3 n 2). Our method also gives an independent proof of McKay’s estimate [33] for the number of such graphs.

Our approach is based on sequential importance sampling (SIS) technique that has been recently successful for counting graphs [15,11,10]. Unfortunately validity of the SIS method is only known through simulations and our work together with [10] are the first results that analyze the performance of this method.

Moreover, we show that for d = O(n 1/2 − τ ), our algorithm can generate an asymptotically uniform d-regular graph. Our results are improving the previous bound of d = O(n 1/3 − τ ) due to Kim and Vu [30] for regular graphs.