15 results on '"Ilcinkas, David"'
Search Results
2. Exploration of the T-Interval-Connected Dynamic Graphs: the Case of the Ring
- Author
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Ilcinkas, David and Wade, Ahmed M.
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- 2018
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3. Exploration of Constantly Connected Dynamic Graphs Based on Cactuses
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Ilcinkas, David, Klasing, Ralf, Wade, Ahmed Mouhamadou, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Kobsa, Alfred, editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Weikum, Gerhard, editor, and Halldórsson, Magnús M., editor
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- 2014
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4. Exploration of the T-Interval-Connected Dynamic Graphs: The Case of the Ring
- Author
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Ilcinkas, David, Wade, Ahmed Mouhamadou, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Moscibroda, Thomas, editor, and Rescigno, Adele A., editor
- Published
- 2013
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5. On the Power of Waiting When Exploring Public Transportation Systems
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Ilcinkas, David, Wade, Ahmed Mouhamadou, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Fernàndez Anta, Antonio, editor, Lipari, Giuseppe, editor, and Roy, Matthieu, editor
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- 2011
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6. Optimal Exploration of Terrains with Obstacles
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Czyzowicz, Jurek, Ilcinkas, David, Labourel, Arnaud, Pelc, Andrzej, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, and Kaplan, Haim, editor
- Published
- 2010
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7. Computing Without Communicating: Ring Exploration by Asynchronous Oblivious Robots
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Flocchini, Paola, Ilcinkas, David, Pelc, Andrzej, and Santoro, Nicola
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- 2013
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8. Exploration of carrier-based time-varying networks: The power of waiting.
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Ilcinkas, David and Wade, Ahmed M.
- Subjects
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TIME-varying networks , *PUBLIC transit , *PATIENCE , *GRAPH connectivity , *CARRIERS , *UNITS of time - Abstract
We study the problem of exploration by a mobile entity (agent) of a class of highly dynamic networks, namely the carrier graphs (the C-graphs, modeling public transportation systems, among others). These are defined by a set of carriers following infinitely their prescribed route along the stations of the network. Flocchini, Mans, and Santoro [9] studied this problem in the case when the agent must always travel on the carriers and thus cannot wait on a station. They described the necessary and sufficient conditions for the problem to be solvable and proved that the optimal worst-case number of time units (and thus of moves) to explore a n -node C-graph of k carriers and maximal period p is in Θ (k p 2) in the general case. In this paper, we study the impact of the ability to wait at the stations. We exhibit the necessary and sufficient conditions for the problem to be solvable in this context, and we prove that waiting at the stations allows the agent to reduce the optimal worst-case number of moves by a multiplicative factor of at least Θ (p) , while the worst-case time complexity is reduced to Θ (n p). (In any connected carrier graph, we have n ≤ k p.) We also show some complementary optimal results in specific cases (same period for all carriers, highly connected C-graphs). Finally this new ability allows the agent to completely map the C-graph, in addition to just exploring it. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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9. Puissance de l'attente aux stations pour l'exploration des réseaux de transport public
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Ilcinkas, David, Wade, Ahmed, Algorithmics for computationally intensive applications over wide scale distributed platforms (CEPAGE), Université Sciences et Technologies - Bordeaux 1-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), Combinatoire et Algorithmique, Laboratoire Bordelais de Recherche en Informatique (LaBRI), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), Voir le papier pour les détails., Mathieu, Fabien et Hanusse, Nicolas, ANR-07-BLAN-0322,ALADDIN,Algorithm Design and Analysis for Implicitly and Incompletely Defined Interaction Networks(2007), Université Sciences et Technologies - Bordeaux 1 (UB)-Inria Bordeaux - Sud-Ouest, Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), Ilcinkas, David, Blanc - Algorithm Design and Analysis for Implicitly and Incompletely Defined Interaction Networks - - ALADDIN2007 - ANR-07-BLAN-0322 - BLANC - VALID, and Mathieu, Fabien et Hanusse, Nicolas
- Subjects
[INFO.INFO-DS]Computer Science [cs]/Data Structures and Algorithms [cs.DS] ,[INFO.INFO-DC] Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC] ,Graphes dynamiques ,PV-graphes ,[INFO.INFO-DS] Computer Science [cs]/Data Structures and Algorithms [cs.DS] ,Exploration ,Agent mobile ,[INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC] - Abstract
International audience; Nous étudions le problème de l'exploration, par une entité mobile, d'une classe de graphes dynamiques appelés graphes périodiquement variables (PV-graphes). Ils sont définis par un ensemble de transporteurs suivant infiniment leur route respective le long des stations du réseau, et modélisent donc naturellement les réseaux de transport public. Flocchini, Mans et Santoro [FMS09] ont étudié ce problème dans le cas où l'agent doit toujours rester sur les transporteurs. Dans ce papier, nous étudions l'impact de la capacité d'attendre sur les stations. Nous prouvons que l'attente sur les stations permet à l'agent d'atteindre de meilleures complexités en pire cas : le nombre de mouvements est réduit d'un facteur multiplicatif d'au moins Theta(p), et la complexité en temps passe de Theta(kp^2) à Theta(np), où n est le nombre de stations, k le nombre de transporteurs, et p la période maximale (n
- Published
- 2012
10. Complexité en espace de l'exploration de graphes
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Ilcinkas, David, Ilcinkas, David, Laboratoire de Recherche en Informatique (LRI), Université Paris-Sud - Paris 11 (UP11)-CentraleSupélec-Centre National de la Recherche Scientifique (CNRS), Université Paris Sud - Paris XI, and Pierre Fraigniaud
- Subjects
graphs ,complexité en espace ,oracle ,automate fini ,graphes ,[INFO]Computer Science [cs] ,[INFO] Computer Science [cs] ,exploration ,space complexity ,finite automaton - Abstract
Graph Exploration is a problem motivated by several aspects of theoretical computer science, including logic and computational complexity. It has also numerous applications in robotics. In all these contexts, the amount of memory used by the mobile entity (robot, finite automaton, etc.) performing exploration is a key parameter. In this thesis, we study in depth the space complexity of graph exploration, in two different frameworks.In the first part of the thesis, we focus on exploration "without assistance", i.e., the case where the mobile entity does not possess any a priori information about the explored graph. In this context, we prove several lower and upper bounds on the amount of memory necessary and sufficient to the mobile entity for performing exploration of all graphs. In particular, we show that the depth-first search algorithm is optimal in space when the complexity is measured in term of degree and diameter.In the second part of the thesis, we focus on exploration "with assistance", by assuming that an oracle entirely aware of the input graph can help the mobile entity, by providing some information about it. This information is measured by its bit-space complexity, and we are interested in the minimal number of bits that the oracle must provide so that the mobile entity can perform exploration. The information can be either given directly to the entity, or encoded on the vertices of the graph., Le problème de l'exploration de graphes trouve ses motivations en informatique fondamentale, notamment en logique et en théorie de la complexité. Il possède également de nombreuses applications en robotique. Quel que soit le cadre, la quantité de mémoire utilisée par l'entité mobile (robot, automate fini, etc.) effectuant l'exploration est un des paramètres importants à considérer. Dans cette thèse, nous étudions en détail la complexité en espace de l'exploration de graphes, à travers différents modèles. Nous distinguons principalement deux cadres d'études.Dans la première partie de la thèse, nous nous attachons à l'étude de l'exploration ``sans assistance'', c'est-à-dire lorsque l'entité mobile ne possède aucune information sur le graphe à explorer. Dans ce contexte, nous prouvons plusieurs bornes inférieures et supérieures sur la quantité de mémoire nécessaire et suffisante à l'entité pour explorer tous les graphes. En particulier, nous montrons que l'algorithme très simple de parcours en profondeur d'abord est optimal en mémoire lorsque la complexité est exprimée en fonction du degré et du diamètre.Dans la seconde partie de la thèse, nous nous attachons à l'étude de l'exploration ``avec assistance''. Nous considérons un modèle supposant l'existence d'un oracle ayant une connaissance exhaustive du graphe exploré, et capable d'aider l'entité mobile en lui fournissant de l'information. Nous nous intéressons ainsi à la quantité minimale d'information (mesurée en nombre de bits) que l'oracle doit fournir à l'entité pour permettre l'exploration. Cette information peut être soit donnée directement à l'entité, soit codée sur les sommets du graphes.
- Published
- 2006
11. Exploration of the <italic>T</italic>-Interval-Connected Dynamic Graphs: the Case of the Ring.
- Author
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Ilcinkas, David and Wade, Ahmed M.
- Subjects
GRAPH connectivity ,SPANNING trees ,SUBGRAPHS ,COMPUTATIONAL complexity ,EDGES (Geometry) - Abstract
In this paper, we study the
T -interval-connected dynamic graphs from the point of view of the time necessary and sufficient for their exploration by a mobile entity (agent). A dynamic graph (more precisely, an evolving graph) isT -interval-connected (T ≥ 1) if, for every window ofT consecutive time steps, there exists a connected spanning subgraph that is stable (always present) during this period. This property of connection stability over time was introduced by Kuhn, Lynch and Oshman (Kuhn et al.14 ) (STOC 2010). We focus on the case when the underlying graph is a ring of sizen , and we show that the worst-case time complexity for the exploration problem is 2n −T − Θ(1) time units if the agent knows the dynamics of the graph, and n+nmax{1,T−1}(δ−1)±Θ(δ)time units otherwise, where δ is the maximum time between two successive appearances of an edge. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
12. Worst-case optimal exploration of terrains with obstacles
- Author
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Czyzowicz, Jurek, Ilcinkas, David, Labourel, Arnaud, and Pelc, Andrzej
- Subjects
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RELIEF models , *OBSTACLE avoidance (Robotics) , *POLYGONS , *GEOGRAPHICAL discoveries , *ALGORITHMS , *COMPUTATIONAL complexity - Abstract
Abstract: A mobile robot represented by a point moving in the plane has to explore an unknown flat terrain with impassable obstacles. Both the terrain and the obstacles are modeled as arbitrary polygons. We consider two scenarios: the unlimited vision, when the robot situated at a point p of the terrain explores (sees) all points q of the terrain for which the segment pq belongs to the terrain, and the limited vision, when we require additionally that the distance between p and q is at most 1. All points of the terrain (except obstacles) have to be explored and the performance of an exploration algorithm, called its complexity, is measured by the length of the trajectory of the robot. For unlimited vision we show an exploration algorithm with complexity , where P is the total perimeter of the terrain (including perimeters of obstacles), D is the diameter of the convex hull of the terrain, and k is the number of obstacles. We do not assume knowledge of these parameters. We also prove a matching lower bound showing that the above complexity is optimal, even if the terrain is known to the robot. For limited vision we show exploration algorithms with complexity , where A is the area of the terrain (excluding obstacles). Our algorithms work either for arbitrary terrains (if one of the parameters A or k is known) or for c-fat terrains, where c is any constant (unknown to the robot) and no additional knowledge is assumed. (A terrain with obstacles is c-fat if , where R is the radius of the smallest disc containing and r is the radius of the largest disc contained in .) We also prove a matching lower bound on the complexity of exploration for limited vision, even if the terrain is known to the robot. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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13. Remembering without memory: Tree exploration by asynchronous oblivious robots
- Author
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Flocchini, Paola, Ilcinkas, David, Pelc, Andrzej, and Santoro, Nicola
- Subjects
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COMPUTER storage devices , *TREE graphs , *ASYNCHRONOUS circuits , *ROBOTS , *ALGORITHMS , *SWARM intelligence , *GRAPH labelings , *COMPUTATIONAL complexity - Abstract
Abstract: In an effort to understand the algorithmic limitations of computing by a swarm of robots, the research has focused on the minimal capabilities that allow a problem to be solved. The weakest of the commonly used models is Asynch where the autonomous mobile robots, endowed with visibility sensors (but otherwise unable to communicate), operate in Look-Compute-Move cycles performed asynchronously for each robot. The robots are often assumed (or required to be) oblivious: they keep no memory of observations and computations made in previous cycles. We consider the setting when the robots are dispersed in an anonymous and unlabeled graph, and they must perform the very basic task of exploration: within finite time every node must be visited by at least one robot and the robots must enter a quiescent state. The complexity measure of a solution is the number of robots used to perform the task. We study the case when the graph is an arbitrary tree and establish some unexpected results. We first prove that, in general, exploration cannot be done efficiently. More precisely we prove that there are -node trees where robots are necessary; this holds even if the maximum degree is . On the other hand, we show that if the maximum degree is , it is possible to explore with only robots. The proof of the result is constructive. We also prove that the size of the team used in our solution is asymptotically optimal: there are trees of degree , whose exploration requires robots. Our final result shows that the difficulty in tree exploration comes in fact from the symmetries of the tree. Indeed, we show that, in order to explore trees that do not have any non-trivial automorphisms, 4 robots are always sufficient and often necessary. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
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14. Exploration of the T-Interval-Connected Dynamic Graphs: the Case of the Ring
- Author
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David Ilcinkas, Ahmed Mouhamadou Wade, Laboratoire Bordelais de Recherche en Informatique (LaBRI), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), Algorithmics for computationally intensive applications over wide scale distributed platforms (CEPAGE), Université Sciences et Technologies - Bordeaux 1-Inria Bordeaux - Sud-Ouest, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), Combinatoire et Algorithmique, Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), See paper for details., ANR-11-BS02-0014,DISPLEXITY,Calculabilité et complexité en distribué(2011), Ilcinkas, David, BLANC - Calculabilité et complexité en distribué - - DISPLEXITY2011 - ANR-11-BS02-0014 - BLANC - VALID, Ecole polytechnique de Thiès, Ecole Polytechnique de Thiès, ANR-13-JS02-0002,MACARON,Bouger et Calculer: Agents, Robots et Réseaux(2013), Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Inria Bordeaux - Sud-Ouest, and Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[INFO.INFO-DS]Computer Science [cs]/Data Structures and Algorithms [cs.DS] ,[INFO.INFO-DS] Computer Science [cs]/Data Structures and Algorithms [cs.DS] ,0102 computer and information sciences ,02 engineering and technology ,Exploration problem ,[INFO.INFO-DM]Computer Science [cs]/Discrete Mathematics [cs.DM] ,01 natural sciences ,Stability (probability) ,Theoretical Computer Science ,Combinatorics ,0202 electrical engineering, electronic engineering, information engineering ,Connection (algebraic framework) ,Time complexity ,Mathematics ,Dynamic graphs ,Discrete mathematics ,Mobile agent ,Ring (mathematics) ,Unit of time ,020206 networking & telecommunications ,T-interval-connectivity ,[INFO.INFO-DM] Computer Science [cs]/Discrete Mathematics [cs.DM] ,Computational Theory and Mathematics ,010201 computation theory & mathematics ,Theory of computation ,Interval (graph theory) ,020201 artificial intelligence & image processing ,Exploration ,[INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC] ,Focus (optics) - Abstract
In this paper, we study the T-interval-connected dynamic graphs from the point of view of the time necessary and sufficient for their exploration by a mobile entity (agent). A dynamic graph (more precisely, an evolving graph) is T-interval-connected (T ≥ 1) if, for every window of T consecutive time steps, there exists a connected spanning subgraph that is stable (always present) during this period. This property of connection stability over time was introduced by Kuhn, Lynch and Oshman (Kuhn et al. 14) (STOC 2010). We focus on the case when the underlying graph is a ring of size n, and we show that the worst-case time complexity for the exploration problem is 2n − T − Θ(1) time units if the agent knows the dynamics of the graph, and $n+ \frac {n}{\max \{1, T-1\} } (\delta -1) \pm {\Theta }(\delta )$ time units otherwise, where δ is the maximum time between two successive appearances of an edge.
- Published
- 2013
15. Complexité de l'exploration par agent mobile des graphes dynamiques
- Author
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WADE, Ahmed Mouhamadou, Klasing, Ralf, Ilcinkas, David, Godard, Emmanuel, Chaumette, Serge, Petit, Franck, and Schabanel, Nicolas
- Subjects
T-intervalle-connexité ,Graphe dynamique ,Exploration ,Agent mobile ,PV-graphe
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