Ex occidente imperium : Alexander the Great and the rise of the Maurya empire

Since the nineteenth century, many authors have seen the campaign of Alexander the Great in the Punjab as a pivotal moment in the history of the Indian subcontinent. British historians writing during the apex of Britain’s colonial rule perceived it as the coming of Western culture and civilisation. Nationalistic Indian historians saw the Maurya Empire, which was established shortly after Alexander’s incursion, as a patriotic reaction to the foreign oppressor. This paper discusses both historiographical interpretations and questions Alexander’s role in the emerging of the Maurya Empire, emphasising underlying structural reasons instead.status: publishe

NAM: Non-Adversarial Unsupervised Domain Mapping

Several methods were recently proposed for the task of translating images between domains without prior knowledge in the form of correspondences. The existing methods apply adversarial learning to ensure that the distribution of the mapped source domain is indistinguishable from the target domain, which suffers from known stability issues. In addition, most methods rely heavily on `cycle' relationships between the domains, which enforce a one-to-one mapping. In this work, we introduce an alternative method: Non-Adversarial Mapping (NAM), which separates the task of target domain generative modeling from the cross-domain mapping task. NAM relies on a pre-trained generative model of the target domain, and aligns each source image with an image synthesized from the target domain, while jointly optimizing the domain mapping function. It has several key advantages: higher quality and resolution image translations, simpler and more stable training and reusable target models. Extensive experiments are presented validating the advantages of our method.Comment: ECCV 201

Fault-Tolerant Consensus in Unknown and Anonymous Networks

This paper investigates under which conditions information can be reliably shared and consensus can be solved in unknown and anonymous message-passing networks that suffer from crash-failures. We provide algorithms to emulate registers and solve consensus under different synchrony assumptions. For this, we introduce a novel pseudo leader-election approach which allows a leader-based consensus implementation without breaking symmetry

Wait-Freedom with Advice

We motivate and propose a new way of thinking about failure detectors which allows us to define, quite surprisingly, what it means to solve a distributed task \emph{wait-free} \emph{using a failure detector}. In our model, the system is composed of \emph{computation} processes that obtain inputs and are supposed to output in a finite number of steps and \emph{synchronization} processes that are subject to failures and can query a failure detector. We assume that, under the condition that \emph{correct} synchronization processes take sufficiently many steps, they provide the computation processes with enough \emph{advice} to solve the given task wait-free: every computation process outputs in a finite number of its own steps, regardless of the behavior of other computation processes. Every task can thus be characterized by the \emph{weakest} failure detector that allows for solving it, and we show that every such failure detector captures a form of set agreement. We then obtain a complete classification of tasks, including ones that evaded comprehensible characterization so far, such as renaming or weak symmetry breaking

On the Space Complexity of Set Agreement

The $k$-set agreement problem is a generalization of the classical consensus problem in which processes are permitted to output up to $k$ different input values. In a system of $n$ processes, an $m$-obstruction-free solution to the problem requires termination only in executions where the number of processes taking steps is eventually bounded by $m$. This family of progress conditions generalizes wait-freedom ($m=n$) and obstruction-freedom ($m=1$). In this paper, we prove upper and lower bounds on the number of registers required to solve $m$-obstruction-free $k$-set agreement, considering both one-shot and repeated formulations. In particular, we show that repeated $k$ set agreement can be solved using $n+2m-k$ registers and establish a nearly matching lower bound of $n+m-k$

Ontwikkeling van een dynamische eindige differentiemethode voor Large-Eddy Simulatie

In de afgelopen decennia erkenden vele onderzoekers de noodzaak om de numerieke kwaliteit van Directe Numerieke Simulaties (DNS) en vooral voor Large-Eddy Simulaties (LES) voor turbulente stromingen te waarborgen. In tegenstelling tot DNS, worden in LES enkel de belangrijkste grootschalige turbulente wervelstructuren in de stroming berekend. Dit impliceert dat de kleinste structuren die berekend worden in LES, relatief belangrijk zijn voor de evolutie van de stromingsoplossing in LES. Bijgevolg dient de numerieke kwaliteit ook voor deze kleine wervels te worden gewaarborgd in LES. Echter, de klassieke eindige differentiebenaderingen, waarbij de nauwkeurigheid van de grootst geresolveerde structuren op het rekenrooster primeert ten koste van de kleinst geresolveerde structuren, zijn vaak suboptimaal voor LES, waar de grootteorde van de kleinste structuren in vele gevallen vergelijkbaar is met deze van de mazen van het rekenrooster. In het huidige proefschrift wordt een familie van dynamische eindige differentiemethoden ontwikkeld, die toelaat de globale numerieke fout op de stromingsoplossing onmiddellijk te minimaliseren tijdens de simulatie. Deze dynamische eindige differentiemethoden bevatten dus het intrinsiek vermogen zich optimaal aan te passen aan de fysische kenmerken van de berekende stroming in relatie tot het rekenrooster. Deze eindige differentiestrategie maakt het mogelijk om steeds een quasi optimale numerieke methode te waarborgen, in overeenstemming met de karakteristieken van de stromingsoplossing op dat moment