COMBINATORIAL OPTIMIZATION TECHNICQUES APPLIED TO A PARALLEL PRECONDITIONER BASED ON THE SPIKE ALGORITHM

Abstract. Parallel algorithms capable to use efficiently thousands of multi-core processors is the trend in High Performance Computing. To achieve a high scalability, hybrid solvers are suitable candidates since they can combine the robustness of direct methods and the low computational cost of iterative methods. The parallel hybrid SPIKE algorith

A comparative study of ant colony optimization and reactive search for graph matching problems

Abstract. Many applications involve matching two graphs in order to identify their common features and compute their similarity. In this paper, we address the problem of computing a graph similarity measure based on a multivalent graph matching and which is generic in the sense that other well known graph similarity measures can be viewed as special cases of it. We propose and compare two different kinds of algorithms: an Ant Colony Optimization based algorithm and a Reactive Search. We compare the efficiency of these two algorithms on two different kinds of difficult graph matching problems and we show that they obtain complementary results.

Parallel Real Root Isolation using the Descartes Method

Many sequential methods for polynomial real root isolation proceed by interval bisection. The associated binary search trees tend to be narrow and hence do not offer much parallelism. For this reason, it is not obvious how real roots can be isolated in parallel. The paper presents an approach that parallelizes the computations associated with each node of the search tree. In the Descartes method these computations can be modeled by a pyramid dag. The pyramid dag is scheduled using a new method that has linear communication overhead. This method can also be used for a number of dynamic programming problems. In addition to parallelizing node computations, the parallel Descartes method exploits any available parallelism at the search tree level. The (parallel) computations associated with the search nodes in each tree level are scheduled using a new centralized method for distributing uniform parallelizable tasks. When isolating the real roots of random polynomials of degrees ..