Problems from the Eighteenth British Combinatorial Conference

Problems from the Nineteenth British Combinatorial Conference

Most of these problems were presented at the problem session of the 19th British Combinatorial Conference at the University College of North Wales, Bangor, 29 June–4 July 2001. I have added some problems given to me after the session. As previously, the problems are circularly ordered; you may start at any point. Problem 1 (BCC19.1) Tight single-change covering designs. Proposed by D. A. Preece...

Restricted colorings of graphs

The problem of properly coloring the vertices (or edges) of a graph using for each vertex (or edge) a color from a prescribed list of permissible colors, received a considerable amount of attention. Here we describe the techniques applied in the study of this subject, which combine combinatorial, algebraic and probabilistic methods, and discuss several intriguing conjectures and open problems. ...

Phraseological Units as a Mirror of National Mentality

The relevance of the study is caused by the continuing interest of linguists to the problem of phraseology as a special – national – sign in the language system, reflecting the national-cultural features of the perception of the world, national mentality, ideological and mental attitudes of native speakers. The analysis of scientific literature showed that the phraseological layer reflecting th...

Notes from ophthalmic practice in the eighteenth century.

Optimization of profit and customer satisfaction in combinatorial production and purchase model by genetic algorithm

Optimization of inventory costs is the most important goal in industries. But in many models, the constraints are considered simple and relaxed. Some actual constraints are to consider the combinatorial production and purchase models in multi-products environment. The purpose of this article is to improve the efficiency of inventory management and find the economic order quantity and economic p...