In this report we show, that an arbitrary MinSum problem (i.e. a MinSum problem with an arbitrary finite set of states) can be adequately transformed into a binary one (i.e. into a MinSum problem with only two states). Consequently all known results for binary MinSum problems can be easily extended to the general case. For instance it gives the possibility to solve exactly submodular MinSum pro...

The following equivalent results in the Boolean lattice 2 are proven. (a) Every fibre of 2 contains a maximal chain. (b) Every cutset of 2 contains a maximal antichain. (c) Every red-blue colouring of the vertices of 2 produces either a red maximal chain or a blue maximal antichain. (d) Given any n antichains in 2 there is a disjoint maximal antichain. Statement (a) is then improved to: (a') Ev...

It is well-know that the Chvátal-Gomory (CG) closure of a rational polyhedron is a rational polyhedron. In this paper, we show that the CG closure of a bounded full-dimensional ellipsoid, described by rational data, is a rational polytope. To the best of our knowledge, this is the first extension of the polyhedrality of the CG closure to a nonpolyhedral set. A key feature of the proof is to ver...

A set function is a function defined on a set family. It is said to be symmetric if the value for each set coincides with that for its complement. A cut capacity function of an undirected graph or hypergraph is a fundamental example of symmetric set functions, and is also submodular if the capacity on each edge or hyperedge is nonnegative. Fujishige and Patkar (2001) provided necessary and suff...

We consider several families of combinatorial polytopes associated with the following NP-complete problems: maximum cut, Boolean quadratic programming, quadratic linear ordering, quadratic assignment, set partition, set packing, stable set, 3-assignment. For comparing two families of polytopes we use the following method. We say that a family P is affinely reduced to a family Q if for every pol...

We obtain a number of lower bounds on the running time of algorithms solving problems on graphs of bounded treewidth. We prove the results under the Strong Exponential Time Hypothesis of Impagliazzo and Paturi. In particular, assuming that SAT cannot be solved in (2−ǫ)m time, we show that for any ǫ > 0; • INDEPENDENT SET cannot be solved in (2 − ǫ)tw(G)|V (G)| time, • DOMINATING SET cannot be s...

We use the generalization of the Laplacian matrix to hypergraphs to obtain several spectral-like results on partition problems in hypergraphs which are computationally difficult to solve (NP-hard or NP-complete). Therefore it is very important to obtain nontrivial bounds. More precisely, the following parameters are bounded in the paper: bipartition width, averaged minimal cut, isoperimetric nu...

Given a graph G = (V,E), let P be a partition of V . We say that P is dominating if, for each part P of P, the set V \ P is a dominating set in G (equivalently, if every vertex has a neighbour of a different colour from its own). We say that P is acyclic if for any parts P, P ′ of P, the bipartite subgraph G[P, P ′] consisting of the edges between P and P ′ in P contains no cycles. The acyclic ...

A cutset in the poset 2, of subsets of {1, . . . , n} ordered by inclusion, is a subset of 2 that intersects every maximal chain. Let 0 ≤ α ≤ 1 be a real number. Is it possible to find a cutset in 2 that, for each 0 ≤ i ≤ n, contains at most α ( n i ) subsets of size i? Let α(n) be the greatest lower bound of all real numbers for which the answer is positive. In this note we prove the rather su...