References of "Lecture Notes in Computer Science"
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See detailAn Econometric Analysis of Homeownership Determinants in Belgium
Xhignesse, Guillaume ULg; Bianchet, Bruno ULg; Cools, Mario ULg et al

in Lecture Notes in Computer Science (2014, July), 8581

In market economies, homeownership is associated with positive ex- ternalities. Increasing the levels of homeownership has been an objective of governments for the last decades. The analysis of the ... [more ▼]

In market economies, homeownership is associated with positive ex- ternalities. Increasing the levels of homeownership has been an objective of governments for the last decades. The analysis of the determinants of tenure sta- tus provides information to this end. This paper proposes an econometric analysis of housing tenure in Belgium. We review the main variables that have been considered in the literature as influencing housing tenure, after what we estimate a logit model. We observe a strong influence of income and age on the probability of homeownership. Couple relationship and the presence of dependent children have a positive influence, but this influence is less significant. Urban location is associated with lower probability of homeownership, compared with other areas. Our observations follow the trends described for other countries in the literature. [less ▲]

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See detailSpatial augmented reality in collaborative design training : articulation between I-space, We-space and Space-between
Ben Rajeb, Samia ULg; Leclercq, Pierre ULg

in Lecture Notes in Computer Science (2014), LNCS 8526 / vol 2(part 2), 343-353

This paper analyses the use of augmented reality in advanced project-based training in design. Our study considers how augmented environments can contribute to this type of group training : what types of ... [more ▼]

This paper analyses the use of augmented reality in advanced project-based training in design. Our study considers how augmented environments can contribute to this type of group training : what types of interaction spaces constitute these new learning environments and how are these spaces constructed so as to promote collective reflection ? [less ▲]

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See detailThe impact of expertise on the capture of sketched intentions: perspectives for remote cooperative design
Sutera, Jennifer; Yang, Maria C.; Elsen, Catherine ULg

in Lecture Notes in Computer Science (2014), 8683

The paper describes the way expertise and field-knowledge can impact the transfer of graphical intentions during architectural cooperative design. The analysis of 28 controlled experiments reveals what ... [more ▼]

The paper describes the way expertise and field-knowledge can impact the transfer of graphical intentions during architectural cooperative design. The analysis of 28 controlled experiments reveals what matters in transmitting architectural intents and more specifically underlines how novices’ intuitive, deductive processes based on previous and embodied experiences interestingly complement experts’ knowledge of the architectural field and its semantics. The results directly inform how we, as researchers, designers and engineers, should take advantage of both novices’ and experts’ strategies to develop tools, methods or interfaces to support next generation cooperative design. [less ▲]

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See detailAcceleration of Affine Hybrid Transformations
Boigelot, Bernard ULg; Herbreteau, Frédéric; Mainz, Isabelle ULg

in Lecture Notes in Computer Science (2014), 8837

This work addresses the computation of the set of reachable configurations of linear hybrid automata. The approach relies on symbolic state-space exploration, using acceleration in order to speed up the ... [more ▼]

This work addresses the computation of the set of reachable configurations of linear hybrid automata. The approach relies on symbolic state-space exploration, using acceleration in order to speed up the computation and to make it terminate for a broad class of systems. Our contribution is an original method for accelerating the control cycles of linear hybrid automata, i.e., to compute their unbounded repeated effect. The idea consists in analyzing the data transformations that label these cycles, by reasoning about the geometrical features of the corresponding system of linear constraints. This approach is complete over Multiple Counters Systems (MCS), and is able to accelerate hybrid transformations that are out of scope of existing techniques. [less ▲]

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See detailSelf-shuffling words
Charlier, Emilie ULg; Kamae, Teturo; Puzynina, Svetlana et al

in Lecture Notes in Computer Science (2013)

In this paper we introduce and study a new property of infinite words which is invariant under the action of a morphism: We say an infinite word x, defined over a finite alphabet A, is self-shuffling if x ... [more ▼]

In this paper we introduce and study a new property of infinite words which is invariant under the action of a morphism: We say an infinite word x, defined over a finite alphabet A, is self-shuffling if x admits factorizations: x=\prod_{i=1}^\infty U_iV_i=\prod_{i=1}^\infty U_i=\prod_{i=1}^\infty V_i with U_i,V_i \in \A^+. In other words, there exists a shuffle of x with itself which reproduces x. The morphic image of any self-shuffling word is again self-shuffling. We prove that many important and well studied words are self-shuffling: This includes the Thue-Morse word and all Sturmian words (except those of the form aC where a is a letter and C is a characteristic Sturmian word). We further establish a number of necessary conditions for a word to be self-shuffling, and show that certain other important words (including the paper-folding word and infinite Lyndon words) are not self-shuffling. In addition to its morphic invariance, which can be used to show that one word is not the morphic image of another, this new notion has other unexpected applications: For instance, as a consequence of our characterization of self-shuffling Sturmian words, we recover a number theoretic result, originally due to Yasutomi, which characterizes pure morphic Sturmian words in the orbit of the characteristic. [less ▲]

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See detailOn the Number of Abelian Bordered Words
Rampersad, Narad; Rigo, Michel ULg; Salimov, Pavel ULg

in Lecture Notes in Computer Science (2013), 7907

In the literature, many bijections between (labeled) Motzkin paths and various other combinatorial objects are studied. We consider abelian (un)bordered words and show the connection with irreducible ... [more ▼]

In the literature, many bijections between (labeled) Motzkin paths and various other combinatorial objects are studied. We consider abelian (un)bordered words and show the connection with irreducible symmetric Motzkin paths and paths in Z not returning to the origin. This study can be extended to abelian unbordered words over an arbitrary alphabet and we derive expressions to compute the number of these words. In particular, over a 3-letter alphabet, the connection with paths in the triangular lattice is made. Finally, we study the lengths of the abelian unbordered factors occurring in the Thue--Morse word. [less ▲]

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See detailAnother Generalization of Abelian Equivalence: Binomial Complexity of Infinite Words
Rigo, Michel ULg; Salimov, Pavel ULg

in Lecture Notes in Computer Science (2013), 8079

The binomial coefficient of two words u and v is the number of times v occurs as a subsequence of u. Based on this classical notion, we introduce the m-binomial equivalence of two words refining the ... [more ▼]

The binomial coefficient of two words u and v is the number of times v occurs as a subsequence of u. Based on this classical notion, we introduce the m-binomial equivalence of two words refining the abelian equivalence. The m-binomial complexity of an infinite word x maps an integer n to the number of m-binomial equivalence classes of factors of length n occurring in x. We study the first properties of m-binomial equivalence. We compute the m-binomial complexity of the Sturmian words and of the Thue-Morse word. We also mention the possible avoidance of 2-binomial squares. [less ▲]

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See detailAutomata-Based Symbolic Representations of Polyhedra
Boigelot, Bernard ULg; Brusten, Julien ULg; Degbomont, Jean-François ULg

in Lecture Notes in Computer Science (2012, March), 7183

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See detailWhat do strokes teach us about collaborative design ?
Elsen, Catherine ULg; Darses, Francoise; Leclercq, Pierre ULg

in Lecture Notes in Computer Science (2012), 7467

Understanding collaborative design goes far beyond analyzing group dynamics, tasks allocations or negotiation during decision-making processes. In this paper, we focused on the collaborative sketching ... [more ▼]

Understanding collaborative design goes far beyond analyzing group dynamics, tasks allocations or negotiation during decision-making processes. In this paper, we focused on the collaborative sketching process, during which the intentions of designers are supported by their sketches and by specific strokes.Twelve professional designers attended an experimental design session, where they were asked to express, share, capture or interpret sketches. A qualitative and quantitative fine-grained analysis of strokes teach us (i) how designers tend to deal with representations that are not theirs; (ii) what main graphical key-features constitute the inner nature of the shared information and (iii) how and when can this graphic essence be shared with collaborators. [less ▲]

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See detailA Verification-Based Approach to Memory Fence Insertion in Relaxed Memory Systems
Linden, Alexander ULg; Wolper, Pierre ULg

in Lecture Notes in Computer Science (2011, July)

This paper addresses the problem of verifying and correcting programs when they are moved from a sequential consistency execution environment to a relaxed memory context. Specifically, it considers the ... [more ▼]

This paper addresses the problem of verifying and correcting programs when they are moved from a sequential consistency execution environment to a relaxed memory context. Specifically, it considers the TSO (Total Store Order) relaxation, which corresponds to the use of store buffers, and its extension x86-TSO, which in addition allows synchronization and lock operations. The proposed approach uses a previously developed verification tool that uses finite automata to symbolically represent the possible contents of the store buffers. Its starting point is a program that is correct for the usual sequential consistency memory model, but that might be incorrect under x86-TSO. This program is then analyzed for this relaxed memory model and when errors are found (with respect to safety properties), memory fences are inserted in order to avoid these errors. The approach proceeds iteratively and heuristically, inserting memory fences until correctness is obtained, which is guaranteed to happen. An advantage of our technique is that the underlying symbolic verification tool makes a full exploration possible even for cyclic programs, which makes our approach broadly applicable. The method has been tested with an experimental implementation and can effectively handle a series of classical examples. [less ▲]

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See detailFinding Routing Shortcuts using an Internet Coordinate System
Cantin, François ULg; Leduc, Guy ULg

in Lecture Notes in Computer Science (2011, February 23), 6557

Overlay routing is a promising way to improve the quality of service in the Internet but its main drawback is scalability: measuring the characteristics of the paths, exchanging the measurement results ... [more ▼]

Overlay routing is a promising way to improve the quality of service in the Internet but its main drawback is scalability: measuring the characteristics of the paths, exchanging the measurement results between the nodes and computing the best routes in the full mesh overlay network generally imply a high consumption of resources. In this paper, we design the basis of a lightweight self-organising one-hop overlay routing mechanism improving the latencies: we define criteria that rely on the information provided by an Internet Coordinate System (ICS) in order to provide a small set of potential one-hop shortcuts for any given path in the network with a small measurement cost. Our best criterion does not guarantee to find the best shortcut for any given path in a network but, even in networks with hundreds or thousands of nodes, it will restrict the search for potential shortcuts to about one or two percent of the total number of nodes. [less ▲]

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See detailFinite orbits of language operations
Charlier, Emilie ULg; Domaratzski, Michael; Harju, Tero et al

in Lecture Notes in Computer Science (2011), 6638

We consider a set of natural operations on languages, and prove that the orbit of any language L under the monoid generated by this set is finite and bounded, independently of L. This generalizes previous ... [more ▼]

We consider a set of natural operations on languages, and prove that the orbit of any language L under the monoid generated by this set is finite and bounded, independently of L. This generalizes previous results about complement, Kleene closure, and positive closure. [less ▲]

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See detailEnumeration and decidable properties of automatic sequences
Charlier, Emilie ULg; Rampersad, Narad; Shallit, Jeffrey

in Lecture Notes in Computer Science (2011), 6795

We show that various aspects of k-automatic sequences — such as having an unbordered factor of length n — are both decidable and effectively enumerable. As a consequence it follows that many related ... [more ▼]

We show that various aspects of k-automatic sequences — such as having an unbordered factor of length n — are both decidable and effectively enumerable. As a consequence it follows that many related sequences are either k-automatic or k-regular. These include many sequences previously studied in the literature, such as the recurrence function, the appearance function, and the repetitivity index. We also give a new characterization of the class of k-regular sequences. Many results extend to other sequences defined in terms of Pisot numeration systems. [less ▲]

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See detailSyntactic complexity of ultimately periodic sets of integers
Rigo, Michel ULg; Vandomme, Elise ULg

in Lecture Notes in Computer Science (2011), 6638

We compute the cardinality of the syntactic monoid of the language 0^∗rep_b(mN) made of base b expansions of the multiples of the integer m. We also give lower bounds for the syntactic complexity of any ... [more ▼]

We compute the cardinality of the syntactic monoid of the language 0^∗rep_b(mN) made of base b expansions of the multiples of the integer m. We also give lower bounds for the syntactic complexity of any (ultimately) periodic set of integers written in base b. We apply our results to some well studied problem: decide whether or not a b-recognizable sets of integers is ultimately periodic. [less ▲]

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See detailAn Automata-Based Symbolic Approach for Verifying Programs on Relaxed Memory Models
Linden, Alexander ULg; Wolper, Pierre ULg

in Lecture Notes in Computer Science (2010, September)

This paper addresses the problem of verifying programs for the relaxed memory models implemented in modern processors. Specifically, it considers the TSO (Total Store Order) relaxation, which corresponds ... [more ▼]

This paper addresses the problem of verifying programs for the relaxed memory models implemented in modern processors. Specifically, it considers the TSO (Total Store Order) relaxation, which corresponds to the use of store buffers. The proposed approach proceeds by using finite automata to symbolically represent the possible contents of the store buffers. Store, load and commit operations then correspond to operations on these finite automata. The advantage of this approach is that it operates on (potentially infinite) sets of buffer contents, rather than on individual buffer configurations. This provides a way to tame the explosion of the number of possible buffer configurations, while preserving the full generality of the analysis. It is thus possible to check even designs that exploit the relaxed memory model in unusual ways. An experimental implementation has been used to validate the feasibility of the approach. [less ▲]

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See detailNetwork Distance Prediction Based on Decentralized Matrix Factorization
Liao, Yongjun ULg; Geurts, Pierre ULg; Leduc, Guy ULg

in Lecture Notes in Computer Science (2010, May 11), 6091

Network Coordinate Systems (NCS) are promising techniques to predict unknown network distances from a limited number of measurements. Most NCS algorithms are based on metric space embedding and suffer ... [more ▼]

Network Coordinate Systems (NCS) are promising techniques to predict unknown network distances from a limited number of measurements. Most NCS algorithms are based on metric space embedding and suffer from the inability to represent distance asymmetries and Triangle Inequality Violations (TIVs). To overcome these drawbacks, we formulate the problem of network distance prediction as guessing the missing elements of a distance matrix and solve it by matrix factorization. A distinct feature of our approach, called Decentralized Matrix Factorization (DMF), is that it is fully decentralized. The factorization of the incomplete distance matrix is collaboratively and iteratively done at all nodes with each node retrieving only a small number of distance measurements. There are no special nodes such as landmarks nor a central node where the distance measurements are collected and stored. We compare DMF with two popular NCS algorithms: Vivaldi and IDES. The former is based on metric space embedding, while the latter is also based on matrix factorization but uses landmarks. Experimental results show thatDMF achieves competitive accuracy with the double advantage of having no landmarks and of being able to represent distance asymmetries and TIVs. [less ▲]

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See detailNumeration Systems: a Link between Number Theory and Formal Language Theory
Rigo, Michel ULg

in Lecture Notes in Computer Science (2010), 6224

We survey facts mostly emerging from the seminal results of Alan Cobham obtained in the late sixties and early seventies. We do not attempt to be exhaustive but try instead to give some personal ... [more ▼]

We survey facts mostly emerging from the seminal results of Alan Cobham obtained in the late sixties and early seventies. We do not attempt to be exhaustive but try instead to give some personal interpretations and some research directions. We discuss the notion of numeration systems, recognizable sets of integers and automatic sequences. We brie y sketch some results about transcendence related to the representation of real numbers. We conclude with some applications to combinatorial game theory and veri cation of in nite-state systems and present a list of open problems. [less ▲]

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See detailOn the Periodicity of Morphic Words
Halava, Vesa; Harju, Tero; Kärki, Tomi et al

in Lecture Notes in Computer Science (2010), 6224

Given a morphism h prolongable on a and an integer p, we present an algorithm that calculates which letters occur infinitely often in congruent positions modulo p in the infinite word hω(a). As a ... [more ▼]

Given a morphism h prolongable on a and an integer p, we present an algorithm that calculates which letters occur infinitely often in congruent positions modulo p in the infinite word hω(a). As a corollary, we show that it is decidable whether a morphic word is ultimately p-periodic. Moreover, using our algorithm we can find the smallest similarity relation such that the morphic word is ultimately relationally p-periodic. The problem of deciding whether an automatic sequence is ultimately weakly R-periodic is also shown to be decidable. [less ▲]

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See detailAn anthropo-based study of industrial design cooperative practices using "mediating objects"
Elsen, Catherine ULg; Dawans, Arnaud ULg; Leclercq, Pierre ULg

in Lecture Notes in Computer Science (2010), 6240

This paper presents a two months in situ case study analyzing the characteristics of designers’ cooperative work through the use of “mediating objects”. We suggest that the consideration of real and ... [more ▼]

This paper presents a two months in situ case study analyzing the characteristics of designers’ cooperative work through the use of “mediating objects”. We suggest that the consideration of real and evolutionary practices and everyday complementary work tools helps to understand the various cooperative modalities between co-workers and offers good clues for the development of cooperative support systems. [less ▲]

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