Has History Restarted?

Dynamic Symmetry Breaking Restarted

Recently, structural symmetry breaking (SSB), a new technique for breaking all piecewise variable and value symmetry in constraint satisfaction problems (CSPs), was introduced. As of today, it is unclear whether the heavy symmetry filtering that SSB performs is at all worthwhile. This paper has two aims: First, we assess the feasibility of SSB. To this end, we introduce the first random benchma...

Parallel Restarted Search

We consider the problem of parallelizing restarted backtrack search. With few notable exceptions, most commercial and academic constraint programming solvers do not learn no-goods during search. Depending on the branching heuristics used, this means that there are little to no side-effects between restarts, making them an excellent target for parallelization. We develop a simple technique for p...

Why solidification has an S-shaped history

Here we show theoretically that the history of solid growth during ‘‘rapid’’ solidification must be S-shaped, in accord with the constructal law of design in nature. In the beginning the rate of solidification increases and after reaching amaximum it decreasesmonotonically as the volume of solid tends toward a plateau. The S-history is a consequence of four configurations for the flow of heat f...

Restarted Variants of Dqgmres

Complementary cycles of restarted GMRES

Restarted GMRES is one of the most popular methods for solving large nonsymmetric linear systems. The algorithm GMRES(m) restarts every m iterations. It is generally thought the information of previous GMRES cycles is lost at the time of a restart, so that each cycle contributes to the global convergence individually. However, this is not the full story. In this paper, we shed light on the rela...