Asymptotically Optimal Algorithms for Budgeted Multiple Play Bandits

We study a generalization of the multi-armed bandit problem with multiple plays where there is a cost associated with pulling each arm and the agent has a budget at each time that dictates how much she can expect to spend. We derive an asymptotic regret lower bound for any uniformly efficient algorithm in our setting. We then study a variant of Thompson sampling for Bernoulli rewards and a variant of KL-UCB for both single-parameter exponential families and bounded, finitely supported rewards. We show these algorithms are asymptotically optimal, both in rateand leading problem-dependent constants, including in the thick margin setting where multiple arms fall on the decision boundary

Reproducible Host Networking Evaluation with End-to-End Simulation

Networking researchers are facing growing challenges in evaluating and reproducing results for modern network systems. As systems rely on closer integration of system components and cross-layer optimizations in the pursuit of performance and efficiency, they are also increasingly tied to specific hardware and testbed properties. Combined with a trend towards heterogeneous hardware, such as protocol offloads, SmartNICs, and in-network accelerators, researchers face the choice of either investing more and more time and resources into comparisons to prior work or, alternatively, lower the standards for evaluation. We aim to address this challenge by introducing SimBricks, a simulation framework that decouples networked systems from the physical testbed and enables reproducible end-to-end evaluation in simulation. Instead of reinventing the wheel, SimBricks is a modular framework for combining existing tried-and-true simulators for individual components, processor and memory, NIC, and network, into complete testbeds capable of running unmodified systems. In our evaluation, we reproduce key findings from prior work, including dctcp congestion control, NOPaxos in-network consensus acceleration, and the Corundum FPGA NIC.Comment: 15 pages, 10 figures, under submissio

Virtuoso: High Resource Utilization and {\mu}s-scale Performance Isolation in a Shared Virtual Machine TCP Network Stack

Virtualization improves resource efficiency and ensures security and performance isolation for cloud applications. To that end, operators today use a layered architecture that runs a separate network stack instance in each VM and container connected to a separate virtual switch. Decoupling through layering reduces complexity, but induces performance and resource overheads that are at odds with increasing demands for network bandwidth, communication requirements for large distributed applications, and low latency. We present Virtuoso, a new software networking stack for VMs and containers. Virtuoso performs a fundamental re-organization of the networking stack to maximize CPU utilization, enforce isolation, and minimize networking stack overheads. We maximize utilization by running one elastically shared network stack instance on dedicated cores; we enforce isolation by performing central and fine-grained per-packet resource accounting and scheduling; we reduce overheads by building a single-layer data path with a one-shot fast-path incorporating all processing from the TCP transport layer through network virtualization and virtual switching. Virtuoso improves resource utilization by up to 50%, latencies by up to 42% compared to other virtualized network stacks without sacrificing isolation, and keeps processing overhead within 11.5% of unvirtualized network stacks.Comment: Under submission for conference peer revie

Understanding the reconstruction of personal networks through residential migration trajectories

This article examines how residential trajectories influence the spatiality and composition of personal networks. Three mechanisms are considered: the addition of spatially close network members, the selection of spatially distant network members, and the substitution of spatially distant network members by spatially close ones. An ego-centred network analysis combined with sequence analysis of residential experiences is used to capture the personal networks and the residential trajectories of individuals from two birth cohorts in Switzerland. A series of regression models tests the association between the types of personal networks that individuals develop, in terms of both spatial dispersion and composition, and their residential trajectories. The results show that individuals who moved far away from their place of birth are embedded in large and diversified personal networks, which include spatially distant relatives, local nuclear family members, and local friends. On average, individuals who experienced residential migration have larger and more diverse personal networks than individuals who stayed close to their place of birth. The addition mechanism accounts for much of this greater diversity.</p

Migration distance from birthplace and its association with relative income and employment share among heterosexual couples in Switzerland

Among heterosexual couples, employment of the female partner may suffer from household migration often driven by the job of the male partner. Most research has traditionally focused on the distance moved after couple formation and has neglected how far partners live from their birthplaces. Recent life course research has shown that staying in, leaving or returning to the place of origin of one or both partners often reflects couples’ work-family arrangements. This study contributes to this literature by examining the division of employment between partners and their relative contribution to household income according to migration distances. We analyse data from a national sample of economically active individuals living with heterosexual partners in Switzerland. When controlling for selectivity of migrant couples, the analysis confirms that long-distance household migration benefits men’s relative earnings. Among couples who migrated within the same region, employment is more equally shared between partners than among other couples, including non-migrant couples. The relative distance to birthplaces also matters. Women’s contribution to household income is higher among couples in which men migrated close to women’s birthplace and is lower among couples where women migrated close to men’s birthplace compared to women in other couples. This study suggests that future research on household migration should consider important social ties and places beyond the ‘last family move’ and the mechanisms by which these ties and places influence couples’ decisions about where to live together and economic outcomes

Construire la métropole sans vision métropolitaine : une analyse des politiques de transport à Genève

L’article contribue à l’investigation des conditions d’émergence de la métropole comme territoire d’action politique. Il s’appuie sur l’exemple des politiques de transports dans l’aire métropolitaine genevoise. Là, en effet, la conduite de projets à écho métropolitain a été préférée à la constitution d’une nouvelle entité métropolitaine. La tendance majoritaire actuelle, donnant suite à des décennies de prévalence de la pensée libérale puis à vingt ans marqués par le New Regionalism et la gouvernance urbaine, tend à promouvoir la coordination verticale et horizontale, englobant les intérêts privés, la société civile et articulée autour de projets de manière souple et fluide, loin du carcan rigide des institutions. Pourtant, la preuve d’une opérationnalité des formes souples de gouvernance n’est pas étayée par un large spectre de données empiriques. L’ambition de l’article est donc de tenter de répondre à deux questions. Premièrement, sans institution métropolitaine peut-on mener des projets nécessaires à la métropole ? Secondement, les projets menés consolident-ils – ou participent-ils à créer –, via l’émergence d’un référentiel métropolitain, une échelle d'intervention métropolitaine ?This article investigates the conditions necessary for the emergence of the city as a space for political action. It draws on the example of transport policies in Greater Geneva, where the pursuit of projects with metropolitan overtones was favored to the establishment of a new metropolitan entity. The current majority trend, in response to decades of liberal thought and 20 years of New Regionalism and urban governance, tends to promote vertical and horizontal project-centered coordination in a flexible and fluid manner, embracing private interests and civil society without institutional shackles. Yet, evidence of the operability of flexible forms of governance is not supported by a broad spectrum of empirical data. This article aims to answer two questions: First, is it possible to implement projects necessary for the metropolis without a metropolitan institution? Second, do the projects undertaken strengthen, or help to create, a metropolitan scale of intervention through the emergence of a metropolitan frame of reference

Early Childhood Education and Care in Luxembourg - Is attendance influenced by immigration background and socioeconomic status?

For decades, researchers have been raising awareness of the issue of educational inequalities in the multilingual Luxemburgish school system. Especially children from families with a migration background or a lower socio-economic status show large deficits in their language and mathematics competences in comparison to their peers. The same applies to children who do not speak Luxemburgish or German as their first language (Hornung et al., 2021; Sonnleitner et al., 2021). One way to reduce such educational inequalities might be an early and extensive participation in early childhood education and care (ECEC). Indeed, participation in ECEC was found to be positively connected to language and cognitive development in other countries, especially for children from disadvantaged families (Bennett, 2012). However, these children attend ECEC less often (Vandenbroeck & Lazzari, 2014). There are indications that lower parental costs might go hand in hand with a greater attendance of ECEC in general (for a Luxembourgish study, see Bousselin, 2019) and in particular by disadvantaged families (Busse & Gathmann, 2020). The aim of this study is to spotlight the attendance of ECEC in Luxembourg during the implementation of the ECEC reform after 2017 which increased free ECEC hours for all families from 3 to 20 hours a week. We draw on a large dataset of about 35.000 children from the Épreuves Standardisées (ÉpStan, the Luxemburg school monitoring programme) from 2015 to 2021 and investigate which children attend any kind of regulated ECEC service (public, private or family daycare) in which intensity, taking socio-economic and cultural family factors into account. The findings might help to understand in which contexts ECEC attendance should be further encouraged. Implications for future policy decisions are discussed with the goal of further promoting equal educational opportunities for all children

Vers des chantiers furtifs ; Etude préliminaire en matière d'acceptabilité et de perceptions des chantiers en contexte urbain

Le laboratoire de Sociologie urbaine (LaSUR) à l’Ecole Polytechnique Fédérale de Lausanne (EPFL) et le collectif Urbz à Genève ont été mandatés conjointement en octobre 2016 par Colas SA, domiciliée à Boulogne-Billancourt (F), afin d’identifier les thématiques et questions de recherche dans le domaine de la perception des chantiers urbains. Ce rapport est le fruit de la collaboration entre le LaSUR, qui a dirigé la pré-étude, et le collectif urbz, qui a tenté de se rapprocher au plus près des acteurs de trois chantiers à Genève et Lausanne. La manière dont sont perçus les chantiers semble s’être dégradée ces dernières années, alors que les projets de constructions battent leur plein en Suisse romande. Avec cette étude, nous touchons à un point particulièrement sensible du processus de développement et d’entretien de la ville. La question du rapport entre le chantier et les usagers du quartier et des infrastructures publiques est essentielle puisque ce sont eux qui sont in ne les béné ciaires des projets de construction (en particulier quand il s’agit de travaux de voirie). La relation avec le public est importante pour les entreprises qui sont sur le terrain - et donc en prise direct avec les usagers - mais aussi bien sûr pour les collectivités publiques. Tout chantier rassemble une série d’acteurs devant entrer en relation les uns avec les autres à différents moments et à différents niveaux. Il nous a paru essentiel de mettre ces relations en évidence. Très tôt dans l’étude, il est apparu que le ot d’information circulant d’un acteur à l’autre jouait un rôle essentiel dans l’acceptabilité du chantier. L’acceptabilité ne repose en effet pas uniquement sur des critères objectifs. Comme le montre nos notes de terrain, les riverains répondent positivement à une bonne communication - et réagissent négativement à un manque de communication. Ces réactions négatives peuvent se traduire en incivilités ou dans une mauvaise perception de l’action publique dont le but est pourtant d’améliorer l’espace public et les infrastructures. Ce rapport présente les données récoltées pendant les huit mois de l’étude sur trois chantiers : Perly et Grand-Pré à Genève et César-Roux à Lausanne. Durant cette période, plus de 40 entretiens ont été conduits et plus de 110 personnes ont été sondées. En plus des données qualitatives collectées auprès des usagers, riverains, commerçants et acteurs du chantier, le rapport contient de nombreux diagrammes, schémas, cartes et tableaux présentant les données objectives du chantier. Le présent rapport fait la synthèse des travaux effectués entre octobre 2016 et juin 2017, en vue du lancement éventuel d’une recherche plus importante. Il présente tout d’abord la méthodologie appliquée, puis détaille les enseignements mis en lumière et en n, les pistes à retenir pour une poursuite de la recherche. Cette première partie constitue l’analyse synthétique. Il s’accompagne d’un rapport de terrain fouillé retraçant les différentes observations empiriques réalisées qui mettent en évidence la perception des différents acteurs du chantier ; la nature des nuisances perçues ; certaines thématiques de recherche et suggère des moyens pour anticiper les nuisances et les minimiser, ainsi que pour rendre les chantiers plus acceptables pour les riverains, commerçants et usagers