The Bipartite Contraction problem is to decide, given a graph G and a parameter k, whether we can can obtain a bipartite graph from G by at most k edge contractions. The fixed-parameter tractability of the problem was shown by Heggernes et al. [13], with an algorithm whose running time has double-exponential dependence on k. We present a new randomized FPT algorithm for the problem, which is bo...

By using an extensive panel data set of Italian firms, we show empirically that the fraction of firms that engage in a lumpy investment follows a non-normal, double-exponential distribution across region-year. We propose a simple sectoral model that generates the double-exponential distribution that arises from the complementarity of the firms’ lumpy investments within a region. We calibrate th...