From PDEs to Pfaffian fibrations

We explain how to encode the essential data of a PDE on jet bundle into a more intrinsic object called Pfaffian fibration. We provide motivations to study this new notion and show how prolongations, integrability and linearisations of PDEs generalise to this setting.Comment: 49 pages; v3 several sections rewritten, section 3.4 adde

Worst-case analysis for new online bin packing problems

We consider two new online bin packing problems, the online Variable Cost and Size Bin Packing Problem (o-VCSBPP) and the online Generalized Bin Packing Problem (o-GBPP). We take two well-known bin packing algorithms to address them, the First Fit (FF) and the Best Fit (BF). We show that both algorithms have an asymptotic worst-case ratio bound equal to 2 for the o-VCSBPP and this bound is tight. When there are enough bins of a particular type to load all items, FF and BF also have an absolute worst-case ratio bound equal to 2 for the o-VCSBPP, and this bound is also tight. In addition, we prove that no worst-case ratio bound of FF and BF can be computed for the o-GBPP. Therefore, we consider a natural evolution of these algorithms, the First Fit with Rejection and the Best Fit with Rejection, able to reject inconvenient bins at the end of the process. Similarly, we prove that no worst-case ratio of these algorithms can be computed for the o-GBPP. Finally, we give sucient conditions under which algorithms do not admit any performance ratio, and conclude that the worst-case results obtained for the o-VCSBPP and the o-GBPP also hold for the oine variant of these two problem

Branch-and-price and beam search algorithms for the Generalized Bin Packing Problem

Tech. Rep. CIRRELT-2012-01, CIRRELT, Montreal, Canad

Asymptotic results for the Generalized Bin Packing Problem

We present a worst case analysis for the Generalized Bin Packing Problem, a novel packing problem arising in many Transportation and Logistics settings and characterized by multiple item and bin attributes and by the joint presence of both compulsory and non-compulsory items. As a preliminary worst case analysis has recently been proposed in the literature, we extend this study by proposing semi-online and offline algorithms, extending the well known First Fit Decreasing and Best Fit Decreasing heuristics for the Bin Packing Problem. In particular, we show that knowing part of the instance or the whole instance is not enough for computing worst case ratio bounds

Multiplicative forms and Spencer operators

Motivated by our attempt to recast Cartan’s work on Lie pseudogroups in a more global and modern language, we are brought back to the question of understanding the linearization of multiplicative forms on groupoids and the corresponding integrability problem. From this point of view, the novelty of this paper is that we study forms with coefficients. However, the main contribution of this paper is conceptual: the discovery of the relationship between multiplicative forms and Cartan’s work is explored here to provide a completely new approach to integrability theorems for multiplicative forms. The multiplicative point of view shows that, modulo Lie’s functor, the Cartan Pfaffian system (itself a multiplicative form with coefficients!) is the same thing as the classical Spencer operator