Scheduling reach mahjong tournaments using pseudoboolean constraints

Reach mahjong is a gambling game for 4 players, most popular in Japan, but played internationally, including in amateur tournaments across Europe. We report on our experience of generating tournament schedules for tournaments hosted in the United Kingdom using pseudoboolean solvers. The problem is essentially an extension of the well-studied Social Golfer Problem (SGP) in operations research. However, in our setting, there are further constraints, such as the positions of players within a group, and the structure of the tournament graph, which are ignored in the usual formulation of the SGP. We tackle the problem primarily using the SAT/pseudoboolean solver clasp, but sometimes augmented with an existing local search-based solver for the SGP

Improved Algorithms for Scheduling Unsplittable Flows on Paths

In this paper, we investigate offline and online algorithms for Round-UFPP, the problem of minimizing the number of rounds required to schedule a set of unsplittable flows of non-uniform sizes on a given path with non-uniform edge capacities. Round-UFPP is NP-hard and constant-factor approximation algorithms are known under the no bottleneck assumption (NBA), which stipulates that maximum size of a flow is at most the minimum edge capacity. We study Round-UFPP without the NBA, and present improved online and offline algorithms. We first study offline Round-UFPP for a restricted class of instances called alpha-small, where the size of each flow is at most alpha times the capacity of its bottleneck edge, and present an O(log(1/(1 - alpha)))-approximation algorithm. Our main result is an online O(log log cmax)-competitive algorithm for Round-UFPP for general instances, where cmax is the largest edge capacities, improving upon the previous best bound of O(log cmax) due to [16]. Our result leads to an offline O(min(log n, log m, log log cmax))- approximation algorithm and an online O(min(log m, log log cmax))-competitive algorithm for Round-UFPP, where n is the number of flows and m is the number of edges

HardenedGolo : pour augmenter le niveau de confiance en un code Golo

National audienceCet article décrit un travail préliminaire autour du langage de programmation Golo. Notre objectif est de fournir aux développeurs des outils permettant de renforcer leur confiance en leur code. Pour ce faire, nous avons expérimenté plusieurs approches (test dynamique, analyse de type et preuve de programme) et nous cherchons maintenant des choix pertinents pour avancer dans chacune de ces pistes

Estimer le nombre de solutions des contraintes de cardinalité grâce à leur décomposition range et roots

National audienceEn programmation par contraintes, le choix d’une heuristique de recherche plutôt qu’une autre dépend souvent du problème. Cependant il existe des heuristiques génériques utilisant plutôt des indicateurs sur la structure combinatoire du problème. Les heuristiques "Counting- Based", introduites par Pesant et al., font des choix basés sur une estimation du nombre de solutions restantes dans tel ou tel sous-arbre de l’arbre de recherche. Un inconvénient de ces heuristiques est qu’elles nécessitent des algorithmes de dénombrement spécifiques à chaque contrainte. Cette étude s’intéresse aux contraintes de cardinalité, dont alldifferent, atmost, nvalue, etc... Nous proposons une méthode de comptage de solutions pour les contraintes range et roots, introduites par Bessiere et al. Grâce à la décomposition des contraintes de cardinalité en contraintes range et roots, nous dérivons une méthode systématique de dénombrement de solutions pour la plupart de ces contraintes

Breakout group allocation schedules and the social golfer problem with adjacent group sizes

The current pandemic has led schools and universities to turn to online meeting software solutions such as Zoom and Microsoft Teams. The teaching experience can be enhanced via the use of breakout rooms for small group interaction. Over the course of a class (or over several classes), the class will be allocated to breakout groups multiple times over several rounds. It is desirable to mix the groups as much as possible, the ideal being that no two students appear in the same group in more than one round. In this paper, we discuss how the problem of scheduling balanced allocations of students to sequential breakout rooms directly corresponds to a novel variation of a well-known problem in combinatorics (the social golfer problem), which we call the social golfer problem with adjacent group sizes. We explain how solutions to this problem can be obtained using constructions from combinatorial design theory and how they can be used to obtain good, balanced breakout room allocation schedules. We present our solutions for up to 50 students and introduce an online resource that educators can access to immediately generate suitable allocation schedules

MaxSAT Evaluation 2022 : Solver and Benchmark Descriptions

Non peer reviewe