Alberto Caprara DEIS, Università di Bologna, Viale Risorgimento 2, I-40136 Bologna, Italy, [email protected] Adam N. Letchford Department of Management Science, Lancaster University, Lancaster LA1 4YX, Great Britain, [email protected] Juan-José Salazar-González DEIOC, Universidad de La Laguna, c/ Astrof́ısico Francisco Sánchez, s/n E-38271 La Laguna, Tenerife, Spain, jjsalaza@...

Recent developments both in measurement echniques and reconstruction algorithms have shown the possibility of quasi-real time microwave tomography. These technical developments always require more sophisticated experimental arrangements in order to reduce the microwave circuits complexity, decrease the measurement time, and improve the resolution. This paper deals with the use of crossed linear...

We present a factor 14D approximation algorithm for the minimum linear arrangement problem on series-parallel graphs, where D is the maximum degree in the graph. Given a suitable decomposition of the graph, our algorithm runs in time O(|E|) and is very easy to implement. Its divide-andconquer approach allows for an effective parallelization. Note that a suitable decomposition can also be comput...

The generalized maximum linear arrangement problem is to compute for a given vector x 2 IR n and an n n non-negative symmetric matrix W = (w i;j), a permutation of f1; :::; ng that maximizes P i;j w i ;; j jx j ? x i j. We present a fast 1 3-approximation algorithm for the problem. We present a randomized approximation algorithm with a better performance guarantee for the special case where x i...

We study the problem of arranging circuit components on a straight line so as to minimize the total wire length needed to realize the inter component nets. Branch-and-bound and dynamic programming algorithms that find optimal solutions are presented. In addition, heuristic approaches including some that employ the Monte Carlo method are developed and an experimental evaluation provided.

Scatter search (SS) and path relinking (PR) are evolutionary methods that have been successfully applied to a wide range of hard optimization problems. The fundamental concepts and principles of the methods were first proposed in the 1970s and 1980s, and were based on formulations, dating back to the 1960s, for combining decision rules and problem constraints. The methods use strategies for sea...

We study the optimal linear arrangement (OLA) problem on interval graphs. Several linear layout problems that are NP-hard on general graphs are solvable in polynomial time on interval graphs. We prove that, quite surprisingly, optimal linear arrangement of interval graphs is NP-hard. The same result holds for permutation graphs. We present a lower bound and a simple and fast 2-approximation alg...