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Personalisation of learning in virtual learning environments Verpoorten, Dominique ; ; et al in Lecture Notes in Computer Science (2009), 5794 Personalization of learning has become a prominent issue in the educational field, at various levels. This article elaborates a different view on personalisation than what usually occurs in this area. Its ... [more ▼] Personalization of learning has become a prominent issue in the educational field, at various levels. This article elaborates a different view on personalisation than what usually occurs in this area. Its baseline is that personalisation occurs when learning turns out to become personal in the learner's mind. Through a literature survey, we analyze constitutive dimensions of this inner sense of personalisation. Here, we devote special attention to confronting learners with tracked information. Making their personal interaction footprints visible contrasts with the back-office usage of this data by researchers, instructors or adaptive systems. We contribute a prototype designed for the Moodle platform according to the conceptual approach presented here. [less ▲] Detailed reference viewed: 40 (6 ULg)Detecting Triangle Inequality Violations in Internet Coordinate Systems by Supervised Learning Liao, Yongjun ; ; et al in Lecture Notes in Computer Science (2009, May 12), 5550 Internet Coordinates Systems (ICS) are used to predict Internet distances with limited measurements. However the precision of an ICS is degraded by the presence of Triangle Inequality Violations (TIVs ... [more ▼] Internet Coordinates Systems (ICS) are used to predict Internet distances with limited measurements. However the precision of an ICS is degraded by the presence of Triangle Inequality Violations (TIVs). Simple methods have been proposed to detect TIVs, based e.g. on the empirical observation that a TIV is more likely when the distance is underestimated by the coordinates. In this paper, we apply supervised machine learning techniques to try and derive more powerful criteria to detect TIVs. We first show that (ensembles of) Decision Trees (DTs) learnt on our datasets are very good models for this problem. Moreover, our approach brings out a discriminative variable (called OREE), which combines the classical estimation error with the variance of the estimated distance. This variable alone is as good as an ensemble of DTs, and provides a much simpler criterion. If every node of the ICS sorts its neighbours according to OREE, we show that cutting these lists after a given number of neighbours, or when OREE crosses a given threshold value, achieves very good performance to detect TIVs. [less ▲] Detailed reference viewed: 127 (32 ULg)Interpreted Active Packets for Ephemeral State Processing Routers Martin, Sylvain ; Leduc, Guy in Lecture Notes in Computer Science (2009), 4388 We propose WASP (lightweight and World-friendly Active packets for ephemeral State Processing), a new active platform based on Ephemeral State designed to allow bytecode interpretation on programmable ... [more ▼] We propose WASP (lightweight and World-friendly Active packets for ephemeral State Processing), a new active platform based on Ephemeral State designed to allow bytecode interpretation on programmable datapath elements. We designed WASP to be a good compromise between flexibility (e.g. offering solutions in quality-adaptive multimedia flows, service discovery or mobility support) and safety (i.e. protection of router and network resource). [less ▲] Detailed reference viewed: 27 (7 ULg)User studies of a sketch-based collaborative distant design solution in industrial context Safin, Stéphane ; Leclercq, Pierre in Lecture Notes in Computer Science (2009), (5738), 117-124 Detailed reference viewed: 40 (8 ULg)On the Recognizability of Self-Generating Sets Kärki, Tomi ; Lacroix, Anne ; Rigo, Michel in Lecture Notes in Computer Science (2009), 5734 Let I be a finite set of integers and F be a finite set of maps of the form n->k_i n + l_i with integer coefficients. For an integer base k>=2, we study the k-recognizability of the minimal set X of ... [more ▼] Let I be a finite set of integers and F be a finite set of maps of the form n->k_i n + l_i with integer coefficients. For an integer base k>=2, we study the k-recognizability of the minimal set X of integers containing I and satisfying f(X)\subseteq X for all f in F. In particular, solving a conjecture of Allouche, Shallit and Skordev, we show under some technical conditions that if two of the constants k_i are multiplicatively independent, then X is not k-recognizable for any k>=2. [less ▲] Detailed reference viewed: 59 (17 ULg)Partial Projection of Sets Represented by Finite Automata, with Application to State-Space Visualization Boigelot, Bernard ; Degbomont, Jean-François in Lecture Notes in Computer Science (2009), 5457 Detailed reference viewed: 56 (29 ULg)A Self-Organized clustering scheme for overlay networks Cantin, François ; Gueye, Cheikh Ahmadou Bamba ; Kaafar, Mohamed Ali et al in Lecture Notes in Computer Science (2008, December), 5343 Hierarchical approaches, where nodes are clustered based on their network distances, have been shown to allow for robust and scalable topology-aware overlays. Moreover, recent research works have shown ... [more ▼] Hierarchical approaches, where nodes are clustered based on their network distances, have been shown to allow for robust and scalable topology-aware overlays. Moreover, recent research works have shown that cluster-based deployments of Internet Coordinates Systems (ICS), where nodes estimate both intra-cluster and inter-cluster distances, do mitigate the impact of Triangle Inequality Violations (TIVs) on the distance predictions, and hence offer more accurate internet latency estimations. To allow the construction of such useful clusters we propose a self-organized distributed clustering scheme. For better scalability and efficiency, our algorithm uses the coordinates of a subset of nodes, known by running an ICS system, as first approximations of node positions. We designed and evaluated two variants of this algorithm. The first one, based on some cooperation among nodes, aims at reducing the expected time to construct clusters. The second variant, where nodes are selfish, aims at reducing the induced communication overhead. [less ▲] Detailed reference viewed: 91 (20 ULg)Life and motion configuration: a basis for spatio-temporal generalised reasoning model Hallot, Pierre ; Billen, Roland in Lecture Notes in Computer Science (2008), 5232/2008 Detailed reference viewed: 110 (44 ULg)Texture Classification with Generalized Fourier Descriptors in Dimensionality Reduction Context: an Overview Exploration ; Destain, Marie-France ; et al in Lecture Notes in Computer Science (2008), 5064 In the context of texture classification, this article explores the capacity and the performance of some combinations of feature extraction, linear and nonlinear dimensionality reduction techniques and ... [more ▼] In the context of texture classification, this article explores the capacity and the performance of some combinations of feature extraction, linear and nonlinear dimensionality reduction techniques and several kinds of classification methods. The performances are evaluated and compared in term of classification error. In order to test our texture classification protocol, the experiment carried out images from two different sources, the well known Brodatz database and our leaf texture images database. © 2008 Springer-Verlag Berlin Heidelberg. [less ▲] Detailed reference viewed: 25 (4 ULg)On the Sets of Real Numbers Recognized by Finite Automata in Multiple Bases Boigelot, Bernard ; Brusten, Julien ; in Lecture Notes in Computer Science (2008, July), 5126 This paper studies the expressive power of finite automata recognizing sets of real numbers encoded in positional notation. We consider Muller automata as well as the restricted class of weak ... [more ▼] This paper studies the expressive power of finite automata recognizing sets of real numbers encoded in positional notation. We consider Muller automata as well as the restricted class of weak deterministic automata, used as symbolic set representations in actual applications. In previous work, it has been established that the sets of numbers that are recognizable by weak deterministic automata in two bases that do not share the same set of prime factors are exactly those that are definable in the first order additive theory of real and integer numbers (R, Z, +, <). This result extends Cobham's theorem, which characterizes the sets of integer numbers that are recognizable by finite automata in multiple bases. In this paper, we first generalize this result to multiplicatively independent bases, which brings it closer to the original statement of Cobham's theorem. Then, we study the sets of reals recognizable by Muller automata in two bases. We show with a counterexample that, in this setting, Cobham's theorem does not generalize to multiplicatively independent bases. Finally, we prove that the sets of reals that are recognizable by Muller automata in two bases that do not share the same set of prime factors are exactly those definable in (R, Z, +, <). These sets are thus also recognizable by weak deterministic automata. This result leads to a precise characterization of the sets of real numbers that are recognizable in multiple bases, and provides a theoretical justification to the use of weak automata as symbolic representations of sets. [less ▲] Detailed reference viewed: 102 (33 ULg)Computing Convex Hulls by Automata Iteration Cantin, François ; ; Wolper, Pierre in Lecture Notes in Computer Science (2008, July), 5148 This paper considers the problem of computing the real convex hull of a finite set of n-dimensional integer vectors. The starting point is a finite-automaton representation of the initial set of vectors ... [more ▼] This paper considers the problem of computing the real convex hull of a finite set of n-dimensional integer vectors. The starting point is a finite-automaton representation of the initial set of vectors. The proposed method consists in computing a sequence of automata representing approximations of the convex hull and using extrapolation techniques to compute the limit of this sequence. The convex hull can then be directly computed from this limit in the form of an automatonbased representation of the corresponding set of real vectors. The technique is quite general and has been implemented. Also, our result fits in a wider scheme whose objective is to improve the techniques for converting automata-based representation of constraints to formulas. [less ▲] Detailed reference viewed: 96 (37 ULg)An overlay maintenance protocol for overlay routing on top of ad hoc networks ; Leduc, Guy in Lecture Notes in Computer Science (2008, May), 4982 The protocol described in this paper builds and maintains an overlay topology on top of an ad hoc network. The overlay is intended to be used by a routing application. As flooding is a key component of ... [more ▼] The protocol described in this paper builds and maintains an overlay topology on top of an ad hoc network. The overlay is intended to be used by a routing application. As flooding is a key component of many route discovery mechanisms in MANETs, we evaluate the delivery percentage, bandwidth consumption and time duration of flooding a message on the overlay. We also consider the overlay path stretch as an indicator for the data transfer transmission time. The protocol does not require any information from the underlay routing protocol, nor cooperation from the nodes that do not belong to the overlay. Each overlay node maintains a set of nearest overlay nodes and exchanges its neighbourhood information with them in order to select useful overlay links. Resilience is afforded by setting a minimum number of overlay neighbours. The performance observed over OLSR are good, for all overlay densities and mobility level studied. [less ▲] Detailed reference viewed: 107 (4 ULg)Towards a Two-Tier Internet coordinate system to mitigate the impact of Triangle Inequality Violations Kaafar, Mohamed Ali ; Gueye, Cheikh Ahmadou Bamba ; Cantin, François et al in Lecture Notes in Computer Science (2008, May), 4982 Routing policies or path inflation can give rise to violations of the Triangle Inequality with respect to delay (RTTs) in the Internet. In network coordinate systems, such Triangle Inequality Violations ... [more ▼] Routing policies or path inflation can give rise to violations of the Triangle Inequality with respect to delay (RTTs) in the Internet. In network coordinate systems, such Triangle Inequality Violations (TIVs) will introduce inaccuracy, as nodes in this particular case could not be embedded into any metric space. In this paper, we consider these TIVs as an inherent and natural property of the Internet; rather than trying to remove them, we consider characterizing them and mitigating their impact on distributed coordinate systems. In a first step, we study TIVs existing in the Internet, using different metrics in order to quantify various levels of TIVs’ severity. Our results show that path lengths do have an effect on the impact of these TIVs. In particular, the shorter the link between any two nodes is, the less severe TIVs involved in are. In a second step, we do leverage our study to reduce the impact of TIVs on coordinate systems. We focus on the particular case of the Vivaldi coordinate system and we explore how TIVs may impact its accuracy and stability. In particular, we observed correlation between the (in)stability and high effective error of nodes’ coordinates with respect to their involvement in TIVs situations. We finally propose a Two-Tier architecture opposed to a flat structure of Vivaldi that do mitigate the effect of TIVs on the distances predictions. [less ▲] Detailed reference viewed: 133 (23 ULg)Assessing the geographic resolution of exhaustive tabulation for geolocating Internet hosts ; Gueye, Cheikh Ahmadou Bamba ; in Lecture Notes in Computer Science (2008, April 29) Geolocation of Internet hosts relies mainly on exhaustive tabulation techniques. Those techniques consist in building a database, that keeps the mapping between IP blocks and a geographic location ... [more ▼] Geolocation of Internet hosts relies mainly on exhaustive tabulation techniques. Those techniques consist in building a database, that keeps the mapping between IP blocks and a geographic location. Relying on a single location for a whole IP block requires using a coarse enough geographic resolution. As this geographic resolution is not made explicit in databases, we try in this paper to better understand it by comparing the location estimates of databases with a well-established active measurements-based geolocation technique. We show that the geographic resolution of geolocation databases is far coarser than the resolution provided by active measurements for individual IP addresses. Given the lack of information in databases about the expected location error within each IP block, one cannot havemuch confidence in the accuracy of their location estimates. Geolocation databases should either provide information about the expected accuracy of the location estimates within each block, or reveal information about how their location estimates have been built, unless databases have to be trusted blindly. [less ▲] Detailed reference viewed: 25 (4 ULg)Contributions of a 3D numerical environment for architectural sketches. ; ; Leclercq, Pierre in Lecture Notes in Computer Science (2008) Detailed reference viewed: 31 (5 ULg)A Decision Problem for Ultimately Periodic Sets in Non-standard Numeration Systems Charlier, Emilie ; Rigo, Michel in Lecture Notes in Computer Science (2008), 5162 Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of ... [more ▼] Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of integers such that the language of their greedy representations in this system is accepted by a finite automaton, we consider the problem of deciding whether or not X is a finite union of arithmetic progressions. We obtain a decision procedure under some hypothesis about the considered numeration system. In a second part, we obtain an analogous decision result for a particular class of abstract numeration systems built on an infinite regular language. [less ▲] Detailed reference viewed: 24 (11 ULg)Refining Topological Relations between Regions Considering Their Shapes Billen, Roland ; in Lecture Notes in Computer Science (2008), 5266/2008 Detailed reference viewed: 55 (23 ULg)Creative Sketches Production in Digital Design: A User-Centered Evaluation of a 3D Digital Environment ; ; Leclercq, Pierre in Lecture Notes in Computer Science (2008), 5166 Detailed reference viewed: 24 (2 ULg)"SketSha" or the sketch power to support collaborative design. Elsen, Catherine ; Leclercq, Pierre in Lecture Notes in Computer Science (2008), 5220 This paper presents a new supporting tool for distant collaborative design, named SketSha. This prototype supports the early stages of design and more particularly the initial and crucial step of free ... [more ▼] This paper presents a new supporting tool for distant collaborative design, named SketSha. This prototype supports the early stages of design and more particularly the initial and crucial step of free-hand sketching. SketSha and its particular interface, named the virtual desktop, aim to keep from Front-To-Front collaborative work all the benefits and to appoint to them some of the nowadays IT facilities, in order to manage in a realistic and efficient way a long distance collaboration and to effectively serve the designers’ needs. Our hope is to re-introduce the social aspects and group interactions, crucial for real system efficacy and adaptation to the business world. The paper presents the fundamental assumptions made to implement SketSha, that are questioned and analyzed through a real-size experimentation featuring 30 architecture and building engineering students, working together in real-time in different locations (Belgium and France). This experiment and the necessary survey open up interesting fields of investigations, such as the relevance of the sketch stage and the proposed device to support distant collaborative design in architecture and the benefit it represents for students, in a pedagogical point of view, to merge the IT aspects and the design studio. The methodology and the replicability are analyzed to increase the level and quality of our students’ formation and, finally, a critic of SketSha constitutes a benefit for the developing teams. [less ▲] Detailed reference viewed: 145 (31 ULg)Can Forwarding Loops Appear when Activating iBGP Multipath Load Sharing? Balon, Simon ; Leduc, Guy in Lecture Notes in Computer Science (2007, November), 4866 We analyse the possible consequences of activating iBGP multipath load sharing in a given domain (or AS), which allows for load balancing over multiple exit routers. It has been stated that interdomain ... [more ▼] We analyse the possible consequences of activating iBGP multipath load sharing in a given domain (or AS), which allows for load balancing over multiple exit routers. It has been stated that interdomain routing loops may appear in this case. We show that under reasonable assumptions (which reflect commercial relationships between ASes) such routing loops cannot appear. Furthermore we show that even if theses assumptions are not met, routing loops can only be transient. [less ▲] Detailed reference viewed: 53 (6 ULg) |
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