Let be a G-symmetric graph admitting a nontrivial G-invariant partition B. For B∈B, let D(B)= (B; B(B); I) be the 1-design in which IC for ∈B and C ∈ B(B) if and only if is adjacent to at least one vertex of C, where B(B) is the neighbourhood of B in the quotient graph B of relative to B. In a natural way the setwise stabilizer GB of B in G induces a group of automorphisms of D(B). In this pape...

Declustering problems are well-known in the databases for parallel computing environments. In this paper, we propose a new similarity-based technique for declustering data. The proposed method can adapt to the available information about query distribution (e.g. size, shape and frequency) and can work with alternative atomic data-types. Furthermore, the proposed method is exible and can work wi...

We prove several complexity results about the gap inequalities for the max-cut problem, including: (i) the gap-1 inequalities do not imply the other gap inequalities, unless NP = CoNP; (ii) there must exist non-redundant gap inequalities with exponentially large coefficients, unless NP = CoNP; (iii) the associated separation problem can be solved in finite (doubly exponential) time.

Sdp(G) ≥ Opt(G) ≥ AlgGW (G) Also, we know the following as well, Theorem 1.1. [2] For all graphsG, AlgGW (G) ≥ αGWSdp(G), where αGW is a constant≈ 0.878. But this only gives us a ratio comparing Sdp(G) and AlgGW (G), and is thus a worry in the following sense: If the graph is such that OPT (G) ≈ 0.5, the Goemans Williamson algorithm could actually return a cut of size ≤ 0.5 (if Sdp(G) were also...

This paper presents two path relinking algorithms to solve the unconstrained binary quadratic programming (UBQP) problem. One is based on a greedy strategy to generate the relinking path from the initial solution to the guiding solution and the other operates in a random way. We show extensive computational results on five sets of benchmarks, including 31 large random UBQP instances and 103 str...

-This note discusses the problem of maximizing the rate of flow from one terminal to another, through a network which consists of a number of branches, each of which has a !imited capacity. The main result is a theorem: The maximum possible flow from left to right through a network is equal to the minimum value among all simple cut-sets. This theorem is applied to solve a more general problem, ...

We survey some recent developments in the area of semidefinite optimization applied to integer programming. After recalling some generic modeling techniques to obtain semidefinite relaxations for NP-hard problems, we look at the theoretical power of semidefinite optimization in the context of the Max-Cut and the Coloring Problem. In the second part, we consider algorithmic questions related to ...

It is shown that there exists a positive c so that for any large integer m, any graph with 2m 2 edges contains a bipartite subgraph with at least m 2 + m=2 + c p m edges. This is tight up to the constant c and settles a problem of Erd} os. It is also proved that any triangle-free graph with e > 1 edges contains a bipartite subgraph with at least e 2 +c 0 e 4=5 edges for some absolute positive c...

We have sampled the artist social network of Myspace and to it applied the pairwise relational connectivity measure Minimum cut/Maximum flow. These values are then compared to a pairwise acoustic Earth Mover’s Distance measure and the relationship is discussed. Further, a means of constructing playlists using the maximum flow value to exploit both the social and acoustic distances is realized.