Lower bounds for the condition numbers of the preconditioned systems are obtained for the Bramble-Pasciak-Schatz substructuring preconditioner and the Neumann-Neumann preconditione...
Edge contraction is shown to be a useful mechanism to improve lower bound heuristics for treewidth. A successful lower bound for treewidth is the degeneracy: the maximum over all ...
Hans L. Bodlaender, Arie M. C. A. Koster, Thomas W...
The disjoint paths problem asks, given an graph G and k + 1 pairs of terminals (s0, t0), . . . , (sk, tk), whether there are k + 1 pairwise disjoint paths P0, . . . , Pk, such tha...