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See detailQuelques réflexions autour du Liber de Rectoribus christianis de Sedulius Scottus : contexte(s), patron(s), destinataire(s)
Pettiau, Hérold UL

in Revue Belge de Philologie et d'Histoire (in press)

This contribution aims at providing a review of the different hypotheses for dating and contextualising the writing of Liber de Rectoribus Christianis, a Carolingian mirror of the prince written by ... [more ▼]

This contribution aims at providing a review of the different hypotheses for dating and contextualising the writing of Liber de Rectoribus Christianis, a Carolingian mirror of the prince written by Sedulius Scottus, an Irish scholar whose activity is recorded in Francia media between the 840’s and the early 870’s. The structure of the text is first summarised. The possible contexts of writing are then reviewed following three axis ; 1) a review of the criteria supporting different dating ; 2) the question of Sedulius’s potential sponsors, addressees of his verse pieces, and finally 3) the text’s dedicatees. The attempted conquest by Charles the Bald of the regnum Lotharii end of 869-beginning 870 remains the most credible one. [less ▲]

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See detailBlockchain-based Micropayment Systems: Economic Impact
Khan, Nida UL; Ahmad, Tabrez; State, Radu UL

in ACM IDEAS '19 Proceedings of the 23rd International Database Engineering & Applications Symposium (in press)

The inception of blockchain catapulted the development of innovative use cases utilizing the trustless, decentralized environment, empowered by cryptocurrencies. The envisaged benefits of the technology ... [more ▼]

The inception of blockchain catapulted the development of innovative use cases utilizing the trustless, decentralized environment, empowered by cryptocurrencies. The envisaged benefits of the technology includes the divisible nature of a cryptocurrency, that can facilitate payments in fractions of a cent, enabling micropayments through the blockchain. Micropayments are a critical tool to enable financial inclusion and to aid in global poverty alleviation. The paper conducts a study on the economic impact of blockchain-based micropayment systems, emphasizing their significance for socioeconomic benefit and financial inclusion. The paper also highlights the contribution of blockchain-based micropayments to the cybercrime economy, indicating the critical need of economic regulations to curtail the growing threat posed by the digital payment mechanism. [less ▲]

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See detailUsing crowd-sourced data to analyse the ongoing merger of [ɕ] and [ʃ] in Luxembourgish
Gilles, Peter UL

in Proceedings of the 19th International Congress of Phonetic Sciences. Melbourne, Australia (in press)

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See detailFabricating Modern Societies: Education, Bodies and Minds in the Age of Steel
Priem, Karin UL; Herman, Frederik

Book published by Brill (in press)

Fabricating Modern Societies: Education, Bodies, and Minds in the Age of Steel, edited by Karin Priem and Frederik Herman, offers new interdisciplinary and transnational perspectives on the history of ... [more ▼]

Fabricating Modern Societies: Education, Bodies, and Minds in the Age of Steel, edited by Karin Priem and Frederik Herman, offers new interdisciplinary and transnational perspectives on the history of industrialization and societal transformation in early-twentieth-century Luxembourg. The individual chapters focus on how industrialists addressed a large array of challenges related to industrialization, borrowing and mixing ideas originating in domains such as corporate identity formation, mediatization, scientification, technological innovation, mechanization, capitalism, mass production, medicalization, educationalization, artistic production, and social utopia, while competing with other interest groups who pursued their own goals. The book looks at different focus areas of modernity, and analyzes how humans created, mediated, and interacted with the technospheres of modern societies. [less ▲]

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See detail40. Komplexe Überdachung II: Luxemburg. Die Genese einer neuen Nationalsprache
Gilles, Peter UL

in Herrgen, Joachim; Schmidt, Jürgen-Erich (Eds.) Language and Space - An International Handbook of Linguistic Variation. Vol. 4 Deutsch (in press)

Der Beitrag behandelt die komplexe Sprachensituation Luxemburgs, mit Fokus auf den germanischen Varietäten, i.e. Deutsch und Luxemburgisch, im Hinblick auf Überdachung und ihre sprachgeschichtlichen ... [more ▼]

Der Beitrag behandelt die komplexe Sprachensituation Luxemburgs, mit Fokus auf den germanischen Varietäten, i.e. Deutsch und Luxemburgisch, im Hinblick auf Überdachung und ihre sprachgeschichtlichen Verschiebungen. In dieser varietätenlinguistischen Perspektive liegt der Schwerpunkt auf der äußeren Sprachgeschichte; Aspekte der inneren Sprachgeschichte werden aus Platzgründen lediglich anhand ausgewählter Beispiele thematisiert. [less ▲]

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See detailQuantifying information flow in interactive systems
Mestel, David UL

in 2019 IEEE 32nd Computer Security Foundations Symposium (CSF) (in press)

We consider the problem of quantifying information flow in interactive systems, modelled as finite-state transducers in the style of Goguen and Meseguer. Our main result is that if the system is ... [more ▼]

We consider the problem of quantifying information flow in interactive systems, modelled as finite-state transducers in the style of Goguen and Meseguer. Our main result is that if the system is deterministic then the information flow is either logarithmic or linear, and there is a polynomial-time algorithm to distinguish the two cases and compute the rate of logarithmic flow. To achieve this we first extend the theory of information leakage through channels to the case of interactive systems, and establish a number of results which greatly simplify computation. We then show that for deterministic systems the information flow corresponds to the growth rate of antichains inside a certain regular language, a property called the width of the language. In a companion work we have shown that there is a dichotomy between polynomial and exponential antichain growth, and a polynomial time algorithm to distinguish the two cases and to compute the order of polynomial growth. We observe that these two cases correspond to logarithmic and linear information flow respectively. Finally, we formulate several attractive open problems, covering the cases of probabilistic systems, systems with more than two users and nondeterministic systems where the nondeterminism is assumed to be innocent rather than demonic. [less ▲]

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See detailHigh involvement versus pathological involvement in video games: A crucial distinction for ensuring the validity and utility of gaming disorder
Billieux, Joël UL; Flayelle, Maèva UL; Rumpf, Hans-Jürgen et al

in Current Addiction Reports (in press)

Purpose of review. The year 2018 was marked by the official recognition of Gaming Disorder (GD) as a mental condition with its inclusion in the proposed eleventh edition of the International ... [more ▼]

Purpose of review. The year 2018 was marked by the official recognition of Gaming Disorder (GD) as a mental condition with its inclusion in the proposed eleventh edition of the International Classification of Diseases (ICD-11). Recently, a group of scholars has repeatedly criticized the notion of GD proposed by the World Health Organization (WHO), arguing that its inclusion in ICD-11 will pathologize highly involved but healthy gamers. It is therefore of crucial importance to clarify the characteristics of high involvement versus pathological involvement in video games, the boundaries between these constructs, and the implementation of screening and diagnostic GD tools that distinguish the two. Recent findings. Increasing evidence supports the view that intense video game playing may involve patterns of gaming that are characterized by high involvement but that are non-pathological. Furthermore, some criteria for addictive and related disorders may reflect peripheral features that are not necessarily indicative of pathology, whereas others may reflect core features that are more likely to adequately identify pathological behavior and so have diagnostic validity. Finally, it is key to assess functional impairment associated with gaming, so that a GD diagnosis has clinical utility. Summary. Available evidence supports the crucial need to distinguish between high and pathological involvement in videogames, in order to avoid over-diagnosis and pathologization of normal behavior. The definition of GD adopted in ICD-11 has clinical utility and diagnostic validity since it explicitly mentions the functional impairment caused by problem gaming and its diagnostic guidelines refer to core addiction features, reflecting pathological involvement. [less ▲]

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See detailBorders and Migration
Nienaber, Birte UL

in Wassenberg, Birte; Reitel, Bernard; Thevenet, Anne (Eds.) et al Critical Dictionary on Cross-Border Cooperation in Europe (in press)

See detailLa réintroduction des contrôles frontaliers dans l’Espace Schengen. Réflexions préliminaires pour un agenda de recherche
Evrard, Estelle UL; Sommarribas, Adolfo UL; Nienaber, Birte UL

in Hamez, Grégory; Defays, Jean-Marc (Eds.) Réalités, perceptions et représentations des frontières de l'Union Européenne (in press)

See detailOpen Science Quest
England, Jonathan UL

Learning material (2019)

The Open Science Quest was an activity organised as part of a national Open Science event in Luxembourg at the university library and was displayed for two weeks from 12 to 23 November 2018. Its aim was ... [more ▼]

The Open Science Quest was an activity organised as part of a national Open Science event in Luxembourg at the university library and was displayed for two weeks from 12 to 23 November 2018. Its aim was for library users (mainly Bachelor and Master students) and the event’s attendees (early-career and senior researchers, librarians and research support staff) to explore and discover Open Science practices at their own pace. The activity was stand-alone and promoted independent learning – once set up no external help was needed apart from issuing the diploma and prize for completing the Quest. The aim was also to make the activity as informative and engaging as possible by requiring participants to use a mix of information gathering techniques – text, images and videos presented on the displays, websearch and online tools, (very simple) puzzle-solving. The Quest was created and displayed in such a way that allowed various types of individual learning goals – each display provided knowledge without requiring to do the Quest and the Quest itself could be completed by grasping a minimal of concepts, while allowing participants to get more in-depth knowledge of each subject if they wanted to. [less ▲]

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See detailSingle-peakedness in aggregation function theory
Devillet, Jimmy UL; Couceiro, Miguel; Marichal, Jean-Luc UL

Presentation (2019, May 14)

Due to their great importance in data fusion, aggregation functions have been extensively investigated for a few decades. Among these functions, fuzzy connectives (such as uninorms) play an important role ... [more ▼]

Due to their great importance in data fusion, aggregation functions have been extensively investigated for a few decades. Among these functions, fuzzy connectives (such as uninorms) play an important role in fuzzy logic. We establish a remarkable connection between a family of associative aggregation functions, which includes the class of idempotent uninorms, and the concepts of single-peakedness and single-plateaudness, introduced in social choice theory by D. Black. Finally, we enumerate those orders when the underlying set is finite. [less ▲]

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See detailComputational and symbolic analysis of distance-bounding protocols
Toro Pozo, Jorge Luis UL

Doctoral thesis (2019)

Contactless technologies are gaining more popularity everyday. Credit cards enabled with contactless payment, smart cards for transport ticketing, NFC-enabled mobile phones, and e-passports are just a few ... [more ▼]

Contactless technologies are gaining more popularity everyday. Credit cards enabled with contactless payment, smart cards for transport ticketing, NFC-enabled mobile phones, and e-passports are just a few examples of contactless devices we are familiar with nowadays. Most secure systems meant for these devices presume physical proximity between the device and the reader terminal, due to their short communication range. In theory, a credit card should not be charged of an on-site purchase if the card is not up to a few centimeters away from the payment terminal. In practice, this is not always true. Indeed, some contactless payment protocols, such as Visa's payWave, have been shown vulnerable to relay attacks. In a relay attack, a man-in-the-middle uses one or more relay devices in order to make two distant devices believe they are close. Relay attacks have been implemented also to bypass keyless entry and start systems in various modern cars. Relay attacks can be defended against with distance-bounding protocols, which are security protocols that measure the round-trip times of a series of challenge/response rounds in order to guarantee physical proximity. A large number of these protocols have been proposed and more sophisticated attacks against them have been discovered. Thus, frameworks for systematic security analysis of these protocols have become of high interest. As traditional security models, distance-bounding security models sit within the two classical approaches: the computational and the symbolic models. In this thesis we propose frameworks for security analysis of distance-bounding protocols, within the two aforementioned models. First, we develop an automata-based computational framework that allows us to generically analyze a large class of distance-bounding protocols. Not only does the proposed framework allow us to straightforwardly deliver computational (in)security proofs but it also permits us to study problems such as optimal trade-offs between security and space complexity. Indeed, we solve this problem for a prominent class of protocols, and propose a protocol solution that is optimally secure amongst space-constrained protocols within the considered class. Second, by building up on an existing symbolic framework, we develop a causality-based characterization of distance-bounding security. This constitutes the first symbolic property that guarantees physical proximity without modeling continuous time or physical location. We extend further our formalism in order to capture a non-standard attack known as terrorist fraud. By using our definitions and the verification tool Tamarin, we conduct a security survey of over 25 protocols, which include industrial protocols based on the ISO/IEC 14443 standard such as NXP's MIFARE Plus with proximity check and Mastercard's PayPass payment protocol. For the industrial protocols we find attacks, propose fixes and deliver security proofs of the repaired versions. [less ▲]

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See detailPROVABLE SECURITY ANALYSIS FOR THE PASSWORD AUTHENTICATED KEY EXCHANGE PROBLEM
Lopez Becerra, José Miguel UL

Doctoral thesis (2019)

Password-based Authenticated Key-Exchange (PAKE) protocols allow the establishment of secure communications despite a human-memorable password being the only secret that is previously shared between the ... [more ▼]

Password-based Authenticated Key-Exchange (PAKE) protocols allow the establishment of secure communications despite a human-memorable password being the only secret that is previously shared between the participants. After more than 25 years since the initial proposal, the PAKE problem remains an active area of research, probably due to the vast amount of passwords deployed on the internet as password-based still constitutes the most extensively used method for user authentication. In this thesis, we consider the computational complexity approach to improve the current understanding of the security provided by previously proposed PAKE protocols and their corresponding security models. We expect that this work contributes to the standardization, adoption and more efficient implementation of the considered protocols. Our first contribution is concerning forward secrecy for the SPAKE2 protocol of Abdalla and Pointcheval (CT-RSA 2005). We prove that the SPAKE2 protocol satisfies the so-called notion of weak forward secrecy. Furthermore, we demonstrate that the incorporation of key-confirmation codes in the original SPAKE2 results in a protocol that provably satisfies the stronger notion of perfect forward secrecy. As forward secrecy is an explicit requirement for cipher suites supported in the TLS handshake, we believe our results fill the gap in the literature and facilitate the adoption of SPAKE2 in the recently approved TLS 1.3. Our second contribution is regarding tight security reductions for EKE-based protocols. We present a security reduction for the PAK protocol instantiated over Gap Diffie-Hellman groups that is tighter than previously known reductions. We discuss the implications of our results for concrete security. Our proof is the first to show that the PAK protocol can provide meaningful security guarantees for values of the parameters typical in today's world. Finally, we study the relation between two well-known security models for PAKE protocols. Security models for PAKEs aim to capture the desired security properties that such protocols must satisfy when executed in the presence of an adversary. They are usually classified into i) indistinguishability-based (IND-based) or ii) simulation-based (SIM-based), however, controversy remains within the research community regarding what is the most appropriate security model that better reflects the capabilities that an adversary is supposed to have in real-world scenarios. Furthermore, the relation between these two security notions is unclear and mentioned as a gap in the literature. We prove that SIM-BMP security from Boyko et al. (EUROCRYPT 2000) implies IND-RoR security from Abdalla et al. (PKC 2005) and that IND-RoR security is equivalent to a slightly modified version of SIM-BMP security. We also investigate whether IND-RoR security implies (unmodified) SIM-BMP security. [less ▲]

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See detailLes Lorrains acttifs à l'étranger, analyse au niveau communal
Pigeron-Piroth, Isabelle UL; Helfer, Malte UL

E-print/Working paper (2019)

A growing number of people living in Lorraine cross the border for work. Today, there are more than 100 000 commuters, the majority of them working in Luxembourg. The flow of commuters into Luxembourg is ... [more ▼]

A growing number of people living in Lorraine cross the border for work. Today, there are more than 100 000 commuters, the majority of them working in Luxembourg. The flow of commuters into Luxembourg is on the increase, whereas commuting into Germany continues to shrink. The analysis of com-munes of residence shows a high proportion of cross-border commuters living as the active population in close vicinity to Luxembourg, but many also live in communes further afield; this phenomenon is moving beyond the borders and raises many issues: environmental, social and economic … [less ▲]

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See detailModeling Cellular Differentiation and Reprogramming with Gene Regulatory Networks
del Sol Mesa, Antonio UL

in Modeling Cellular Differentiation and Reprogramming with Gene Regulatory Networks (2019)

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See detailCanonical quantization for compact quantizable Kaehler manifolds
Schlichenmaier, Martin UL

Scientific Conference (2019, May 02)

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See detailInexact Block Coordinate Descent Algorithms for Nonsmooth Nonconvex Optimization
Yang, Yang UL; Pesavento, Marius; Luo, Zhi-Quan et al

E-print/Working paper (2019)

In this paper, we propose an inexact block coordinate descent algorithm for large-scale nonsmooth nonconvex optimization problems. At each iteration, a particular block variable is selected and updated by ... [more ▼]

In this paper, we propose an inexact block coordinate descent algorithm for large-scale nonsmooth nonconvex optimization problems. At each iteration, a particular block variable is selected and updated by solving the original optimization problem with respect to that block variable inexactly. More precisely, a local approximation of the original optimization problem is solved. The proposed algorithm has several attractive features, namely, i) high flexibility, as the approximation function only needs to be strictly convex and it does not have to be a global upper bound of the original function; ii) fast convergence, as the approximation function can be designed to exploit the problem structure at hand and the stepsize is calculated by the line search; iii) low complexity, as the approximation subproblems are much easier to solve and the line search scheme is carried out over a properly constructed differentiable function; iv) guaranteed convergence to a stationary point, even when the objective function does not have a Lipschitz continuous gradient. Interestingly, when the approximation subproblem is solved by a descent algorithm, convergence to a stationary point is still guaranteed even if the approximation subproblem is solved inexactly by terminating the descent algorithm after a finite number of iterations. These features make the proposed algorithm suitable for large-scale problems where the dimension exceeds the memory and/or the processing capability of the existing hardware. These features are also illustrated by several applications in signal processing and machine learning, for instance, network anomaly detection and phase retrieval. [less ▲]

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See detailTowards Massive Machine Type Communications in Ultra-Dense Cellular IoT Networks: Current Issues and Machine Learning-Assisted Solutions
Sharma, Shree Krishna UL; Wang, Xianbin

in IEEE Communications Surveys and Tutorials (2019)

The ever-increasing number of resource-constrained Machine-Type Communication (MTC) devices is leading to the critical challenge of fulfilling diverse communication requirements in dynamic and ultra-dense ... [more ▼]

The ever-increasing number of resource-constrained Machine-Type Communication (MTC) devices is leading to the critical challenge of fulfilling diverse communication requirements in dynamic and ultra-dense wireless environments. Among different application scenarios that the upcoming 5G and beyond cellular networks are expected to support, such as enhanced Mobile Broadband (eMBB), massive Machine Type Communications (mMTC) and Ultra-Reliable and Low Latency Communications (URLLC), the mMTC brings the unique technical challenge of supporting a huge number of MTC devices in cellular networks, which is the main focus of this paper. The related challenges include Quality of Service (QoS) provisioning, handling highly dynamic and sporadic MTC traffic, huge signalling overhead and Radio Access Network (RAN) congestion. In this regard, this paper aims to identify and analyze the involved technical issues, to review recent advances, to highlight potential solutions and to propose new research directions. First, starting with an overview of mMTC features and QoS provisioning issues, we present the key enablers for mMTC in cellular networks. Along with the highlights on the inefficiency of the legacy Random Access (RA) procedure in the mMTC scenario, we then present the key features and channel access mechanisms in the emerging cellular IoT standards, namely, LTE-M and Narrowband IoT (NB-IoT). Subsequently, we present a framework for the performance analysis of transmission scheduling with the QoS support along with the issues involved in short data packet transmission. Next, we provide a detailed overview of the existing and emerging solutions towards addressing RAN congestion problem, and then identify potential advantages, challenges and use cases for the applications of emerging Machine Learning (ML) techniques in ultra-dense cellular networks. Out of several ML techniques, we focus on the application of low-complexity Q-learning approach in the mMTC scenario along with the recent advances towards enhancing its learning performance and convergence. Finally, we discuss some open research challenges and promising future research directions. [less ▲]

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See detailNaviguer dans la Toile du passé
Schafer, Valerie UL

in Lamassé, Stéphane; Bonnot, Gaetan (Eds.) Dans les dédales du Web. Historiens en territoires numériques. (2019)

Les historiens prennent progressivement la mesure de l’opportunité que représentent les milliards de pages Web archivées, mais aussi des difficultés et enjeux épistémologiques posés par ces nouvelles ... [more ▼]

Les historiens prennent progressivement la mesure de l’opportunité que représentent les milliards de pages Web archivées, mais aussi des difficultés et enjeux épistémologiques posés par ces nouvelles sources à la discipline. Parmi les points de tension relevés, ressort en particulier l’imbrication des temporalités à l’œuvre dans l’archivage et les archives du Web. Ce sont ces multiples temporalités de l’archive et de l’archivage que ce chapitre se propose d’étudier. [less ▲]

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See detailReady Player One: UAV Clustering based Multi-Task Offloading for Vehicular VR/AR Gaming
Hu, Long; Tian, Yuanwen; Yang, Jun et al

in IEEE Network (2019)

With rapid development of unmanned aerial vehicle (UAV) technology, application of UAVs for task offloading has received increasing interest in academia. However, real-time interaction between one UAV and ... [more ▼]

With rapid development of unmanned aerial vehicle (UAV) technology, application of UAVs for task offloading has received increasing interest in academia. However, real-time interaction between one UAV and the mobile edge computing node is required for processing the tasks of mobile end users, which significantly increases the system overhead and is unable to meet the demands of large-scale artificial intelligence (AI)-based applications. To tackle this problem, in this article, we propose a new architecture for UAV clustering to enable efficient multi-modal multi-task offloading. With the proposed architecture, the computing, caching, and communication resources are collaboratively optimized using AI-based decision making. This not only increases the efficiency of UAV clusters, but also provides insight into the fusion of computation and communication. [less ▲]