In this paper we consider a mathematical model for the evolution and collapse of the Easter Island society, starting from the fifth century until the last period of the society collapse (fifteen century). Based on historical reports, the available primary sources consisted almost exclusively on the trees. We describe the inhabitants and the resources as an isolated system and both considered as...

Derivative free optimization addresses general nonlinear optimization problems in the cases when obtaining derivative information for the objective and/or the constraint functions is impractical due to computational cost or numerical inaccuracies. Applications of derivative free optimization arise often in engineering design such as circuit tuning, aircraft configuration, water pipe calibration...

The authors exhibit an abelian group not embeddable in a product of copies of Z (the integers) but totally orderable so that every covering pair of convex subgroups has archimedean quotient isomorphic to Z (= g.d.), thus furnishing a counterexample to Théorème 4 on p. 53 of [21]; then go on to show that every countable g.d. group is algebraically free (§4); and purport to show it also embeddabl...

We discuss a generalization of partitions, called overpartitions, which have proven useful in several combinatorial studies of basic hypergeometric series. After showing how a number of finite products occurring in q-series have natural interpretations in terms of overpartitions, we present an introduction to their rich structure as revealed by q-series identities.

Hello everybody! Welcome to this special issue of our Newsletter. It is dedicated to the first PhD-Day organized by the Society to give the opportunity to young Belgian Mathematicians to advertise their work as researchers in mathematics. Organizer of this event: the Belgian Mathematical Society On this day, opportunity is given to Belgian PhD students to present their research and to get to kn...

June 28, 2010. This is the first issue of Optima under our society’s new name, Mathematical Optimization Society. After a vigorous and enlightening discussion, members approved the change by the decisive margin of 457 to 127, with an additional 38 voters registering an abstention. We are working through the many practical issues associated with the change, including a new web address mathopt.or...

We study Einstein metrics on smooth compact 4-manifolds with an edge-cone singularity of specified cone angle along an embedded 2-manifold. To do so, we first derive modified versions of the Gauss–Bonnet and signature theorems for arbitrary Riemannian 4-manifolds with edge-cone singularities, and then show that these yield non-trivial obstructions in the Einstein case. We then use these integra...