On the choosability of claw-free perfect graphs

It has been conjectured that for every claw-free graph $G$ the choice number of $G$ is equal to its chromatic number. We focus on the special case of this conjecture where $G$ is perfect. Claw-free perfect graphs can be decomposed via clique-cutset into two special classes called elementary graphs and peculiar graphs. Based on this decomposition we prove that the conjecture holds true for every claw-free perfect graph with maximum clique size at most $4$

FullSWOF: A free software package for the simulation of shallow water flows

Numerical simulations of flows are required for numerous applications, and are usually carried out using shallow water equations. We describe the FullSWOF software which is based on up-to-date finite volume methods and well-balanced schemes to solve this kind of equations. It consists of a set of open source C++ codes, freely available to the community, easy to use, and open for further development. Several features make FullSWOF particularly suitable for applications in hydrology: small water heights and wet-dry transitions are robustly handled, rainfall and infiltration are incorporated, and data from grid-based digital topographies can be used directly. A detailed mathematical description is given here, and the capabilities of FullSWOF are illustrated based on analytic solutions and datasets of real cases. The codes, available in 1D and 2D versions, have been validated on a large set of benchmark cases, which are available together with the download information and documentation at http://www.univ-orleans.fr/mapmo/soft/FullSWOF/.Comment: 38 page

Nickel sulphide: new results to optimise the heat soak test for thermally toughened building glasses

The spontaneous failure of tempered facade glazings has been known as a security and reputation problem of these beautiful parts of the surface of modern buildings since the late fifties. By kinetic investigations on synthetic nickel sulphides and by statistical analysis of the breakage of heat soak test ovens it is shown that this problem can be solved. If the test is done in a right and careful way, at temperatures of (290 ± 10) °C, holding time need not be longer than 2 to 3 h to fulfil the implicit requirements of the German Standard (DIN 18516). On the other hand, literature data show that it should be possible to further shorten this holding time if it were possible to heat up faster and more homogeneously the glass to be tested

A greedy algorithm for multicut and integral multiflow in rooted trees

We present an O(min(Kn,n2)) algorithm to solve the maximum integral multiflow and minimum multicut problems in rooted trees, where K is the number of commodities and n is the number of vertices. These problems are NP-hard in undirected trees but polynomial in directed trees. In the algorithm we propose, we first use a greedy procedure to build the multiflow then we use duality properties to obtain the multicut and prove the optimality

Multicut and integral multiflow : a survey.

We present a survey about the maximum integral multiflow and minimum multicut problems and their subproblems, such as the multiterminal cut and the unsplittable flow problems. We consider neither continuous multiflow nor minimum cost multiflow. Most of the results are very recent and some are new. We recall the dual relationship between both problems, give complexity results and algorithms, firstly in unrestricted graphs and secondly in several special graphs: trees, bipartite or planar graphs. A table summarizes the most important results

Un illusoire consensus ? La densité politique de la Coupe du monde de football en Amérique latine

L’année 2014 a été chargée au plan politique et sportif en Amérique latine. Parmi les neuf pays de la région qualifiés pour la Coupe du monde masculine de football, qui s’est déroulée du 12 juin au 13 juillet 2014 au Brésil, quatre ont tenu la même année des élections générales : le Costa Rica (février), la Colombie (mai-juin), le Brésil (octobre) et l’Uruguay (octobre). La convergence des calendriers a été particulièrement marquante en Colombie, où le second tour de l’élection présidentielle s’est joué le 15 juin, le lendemain de la victoire de la sélection nationale contre la Grèce. Si aucune étude d’analyse électorale n’a pu, à notre connaissance, prouver une corrélation réelle entre les résultats des équipes nationales de football et les comportements électoraux (vote-sanction en cas de défaite ou vote de reconnaissance en cas de succès), les enjeux politiques du football n’en sont pas moins importants et repérables à différents niveaux. Ils se manifestent avec une vigueur et une visibilité accrues à l’approche d’un événement aussi populaire et médiatisé qu’une Coupe du monde..

Simplified stress analysis of functionally graded single-lap joints subjected to combined thermal and mechanical loads

Functionally graded adhesive (FGA) joints involve a continuous variation of the adhesive properties along the overlap allowing for the homogenization of the stress distribution and load transfer, in order to increase the joint strength. The use of FGA joints made of dissimilar adherends under combined mechanical and thermal loads could then be an attractive solution. This paper aims at presenting a 1D-bar and a 1D-beam simplified stress analyses of such multimaterial joints, in order to predict the adhesive stress distribution along the overlap, as a function of the adhesive graduation. The graduation of the adhesive properties leads to differential equations which coefficients can vary the overlap length. For the 1D-bar analyses, two different resolution schemes are employed. The first one makes use of Taylor expansion power series (TEPS) as already published under pure mechanical load. The second one is based on the macro-element (ME) technique. For the 1D-beam analysis, the solution is only based on the ME technique. A comparative study against balanced and unbalanced joint configurations under pure mechanical and/or thermal loads involving constant or graduated adhesive properties are provided to assess the presented stress analyses. The mathematical description of the analyses is provided