We describe a new partial symmetry breaking method that can be used to break arbitrary variable/value symmetries in combination with depth first search, static value ordering and dynamic variable ordering. The main novelty of the method is a new dominance detection technique based on local search in the symmetry group. It has very low time and memory requirements, yet in preliminary experiments...

A necessary condition for existence of a (v, k, k−1) near resolvable BIBD is v ≡ 1 (mod k). In this paper, we update earlier known existence results when k ∈ {9, 12, 16}, and show this necessary condition is sufficient, except possibly for 26, 37 and 149 values of v for k = 9, 12, 16 respectively. Some new results for existence of (9, 8)-frames of type 9 are also obtained; in particular, we sho...

We prove lower bounds on the largest and second largest eigenvalue of the adjacency matrix of connected bipartite graphs and give necessary and sufficient conditions for equality. We give several examples of classes of graphs that are optimal with respect to the bounds. We prove that BIBD-graphs are characterized by their eigenvalues. Finally we present a new bound on the expansion coefficient ...

Several methods exist for breaking symmetry in constraint problems, but most potentially suffer from high memory requirements, high computational overhead, or both. We describe a new partial symmetry breaking method that can be applied to arbitrary variable/value symmetries. It models dominance detection as a nonstationary optimisation problem, and solves it by resource-bounded metaheuristic se...

The purpose of this paper is to discuss the importance of algebraic coding theory and to investigate the special case in which BIB designs and codes are constructed from planar near-rings. Application of planar near-rings to binary codes were first explored by Modisett [12] and by Fuchs, Hofer and Pilz [14]. Key word: planar near-ring, incidence structure, tactical configuration, BIBD, binary c...

Combinatorial designs have been used to construct digital fingerprint codes. Here, a new constructive algorithm for an anticollusion fingerprint code based on group-divisible designs is presented. These codes are easy to construct and available for a large number of individuals, which is important from a business point of view. Group-divisible designs have not been used previously as a tool for...

in this paper we introduce two symmetric variants of amenability, symmetric module amenability and symmetric connes amenability. we determine symmetric module amenability and symmetric connes amenability of some concrete banach algebras. indeed, it is shown that $ell^1(s)$ is  a symmetric $ell^1(e)$-module amenable if and only if $s$ is amenable, where $s$ is an inverse semigroup with subsemigr...

We study the group test for DNA library screening based on probabilistic approach. Group test is a method of detecting a few positive items from among a large number of items, and has wide range of applications. In DNA library screening, positive item corresponds to the clone having a specified DNA segment, and it is necessary to identify and isolate the positive clones for compiling the librar...

Broadband Fixed Wireless Access (BFWA) systems enable services such as high-speed data communication, high quality voice/video conferencing and high-speed Internet access in areas where a wired link is not possible. However, the BFWA channel is a slow fading channel having deep frequency selective fading caused by clusters of scatterers in the environment that introduce intersymbol interference...

When solving a problem using constraint programming, constraint modelling is widely acknowledged as an important and difficult task. Even a constraint modelling expert may explore many models and spend considerable time modelling a single problem. Therefore any automated assistance in the area of constraint modelling is valuable. Common sub-expression elimination (CSE) is a type of constraint r...