This paper was motivated by a practical optimization problem formulated at the Erdenet Mining Corporation (Mongolia). By solving an identification problem for a chosen design of experiment we developed a quadratic model that quite adequately represents the experimental data. The problem obtained turned out to be the indefinite quadratic program, which we solved by applying the global search theory for a d.c. programming developed by A.S. Strekalovsky [13]- [15] . According to this d.c.

more »

... ion theory, we performed a local search that takes into account the structure of the problem in question, and constructed procedures of escaping critical points provided by the local search. The algorithms proposed for d.c. programming were verified using a set of test problems as well as a copper content maximization problem arising at the mining factory. 2010 Mathematics Subject Classification. Primary: 90C26, 90C90; Secondary: 90C20. Key words and phrases. Identification and modeling, nonconvex optimization, indefinite quadratic programming, difference of two convex functions, local and global searches.