815 research outputs found
Robustness of Distances and Diameter in a Fragile Network
No full textA property of a graph G is robust if it remains unchanged in all connected spanning subgraphs of G. This form of robustness is motivated by networking contexts where some links eventually fail permanently, and the network keeps being used so long as it is connected. It is then natural to ask how certain properties of the network may be impacted as the network deteriorates. In this paper, we focus on two particular properties, which are the diameter, and pairwise distances among nodes. Surprisingly, the complexities of deciding whether these properties are robust are quite different: deciding the robustness of the diameter is coNP-complete, whereas deciding the robustness of the distance between two given nodes has a linear time complexity. This is counterintuitive, because the diameter consists of the maximum distance over all pairs of nodes, thus one may expect that the robustness of the diameter reduces to testing the robustness of pairwise distances. On the technical side, the difficulty of the diameter is established through a reduction from hamiltonian paths. The linear time algorithm for deciding robustness of the distance relies on a new characterization of two-terminal series-parallel graphs (TTSPs) in terms of excluded rooted minor, which may be of independent interest
Almost-Optimal Deterministic Treasure Hunt in Arbitrary Graphs
No full textA mobile agent navigating along edges of a simple connected graph, either finite or countably infinite, has to find an inert target (treasure) hidden in one of the nodes. This task is known as treasure hunt. The agent has no a priori knowledge of the graph, of the location of the treasure or of the initial distance to it. The cost of a treasure hunt algorithm is the worst-case number of edge traversals performed by the agent until finding the treasure. Awerbuch, Betke, Rivest and Singh [Baruch Awerbuch et al., 1999] considered graph exploration and treasure hunt for finite graphs in a restricted model where the agent has a fuel tank that can be replenished only at the starting node s. The size of the tank is B = 2(1+α)r, for some positive real constant α, where r, called the radius of the graph, is the maximum distance from s to any other node. The tank of size B allows the agent to make at most {⌊ B⌋} edge traversals between two consecutive visits at node s.
Let e(d) be the number of edges whose at least one extremity is at distance less than d from s. Awerbuch, Betke, Rivest and Singh [Baruch Awerbuch et al., 1999] conjectured that it is impossible to find a treasure hidden in a node at distance at most d at cost nearly linear in e(d). We first design a deterministic treasure hunt algorithm working in the model without any restrictions on the moves of the agent at cost (e(d) log d), and then show how to modify this algorithm to work in the model from [Baruch Awerbuch et al., 1999] with the same complexity. Thus we refute the above twenty-year-old conjecture. We observe that no treasure hunt algorithm can beat cost Θ(e(d)) for all graphs and thus our algorithms are also almost optimal
Faire un stage de recherche à LAM. Entretien avec Arnaud Dupuy, stagiaire LAM
No full textFree consultation with a Doctor of mobile health team has Madagacar. Author : Docteur Ando. Licence : CC BY SA. https://commons.wikimedia.org/wiki/File:Free_consultation_with_a_Doctor_of_mobile_health_team_has_Madagacar.jpg En mai-juin 2019, Arnaud Dupuy a accompli un stage au laboratoire Les Afriques dans le monde, encadré par Jean-Philippe Berrou, enseignant-chercheur en économie. Il a été impliqué dans deux programmes de recherches pluridisciplinaires concernant l’aire africaine. Qu’est..
Dutch space; interview with Arnaud de Jong, CEO
No full textDutch Space, the largest space company in the Netherlands and part of Airbus Defence and Space, appointed a new CEO last year. The Leonardo Times sat down with the CEO Arnaud de Jong for an interview. We discuss his career, developments in Dutch Space, his take on competition in the commercial space domain and his future outlook on European and International space markets.Aerospace Engineerin
Arnaud François
No full textArnaud François, born in 1978, is a professor of philosophy at the University of Poitiers. He is the author of several books and articles on Bergson, Schopenhauer and Nietzsche, as well as of works on the philosophy of health. He is currently exploring, at the junction between philosophy and literature, the work of Émile Zola. He is, with Ondřej Švec, co-president of the Organisation Francophone pour la Formation et la Recherche Européennes en Sciences humaines (OFFRES), an academic collabora..
Interview with Arnaud Lechevalier on Social Europe
No full textHeike Wieters and Dominique Gareis of Saisir l'Europe - axis Social State have recently conducted an Interview with Arnaud Lechevalier (Maitre de Conferences, Université Paris 1 Panthéon-Sorbonne, researcher at the Laboratoire Interdisciplinaire pour la Sociologie Economique, CNAM-CNRS and at the Centre Marc Bloch, co-author (with Jan Wielgohs, Europa University Viadrina) of the edited volume Social Europe: A Dead End. What the Eurozone Crisis is doing to Europe’s Social Dimension, on social ..
St Arnaud total count grid geodetic
No full textMaintenance and Update Frequency: notPlannedStatement: This St Arnaud total count grid geodetic is an airborne-derived radiometric terrestrial dose rate grid for the St Arnaud Infill merge, 1990 survey. The survey was acquired under the project No. 1345 for the geological survey of VIC. The grid has a cell size of 0.00042 degrees (approximately 42m). A total of 18970 line-kilometres of data at a line spacing between 200m and 400m, and 100m terrain clearance were acquired to produce this grid. The terrestrial dose rate grid is derived as a linear combination of the filtered K, U and Th grids. Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014). This Index is also available online at http://pid.geoscience.gov.au/dataset/79134.
Reference:
Percival, P.J., 2014. Index of airborne geophysical surveys (Fourteenth Edition).The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. The terrestrial dose rate grid is derived as a linear combination of the filtered K, U and Th grids. A low pass filter is applied to this grid to generate the filtered terrestrial dose rate grid.<br/>This St Arnaud total count grid geodetic has a cell size of 0.00042 degrees (approximately 42m) and shows the terrestrial dose rate of the St Arnaud Infill merge, 1990. The data used to produce this grid was acquired in 1990 by the VIC Government, and consisted of 18970 line-kilometres of data at a line spacing between 200m and 400m, and 100m terrain clearance
Density, VC-dimension, and graph labelings
No full textUne partie des résultats de cette thèse sont initialement motivés par l'élaboration de schémas d'étiquetage permettant de réponde à l'adjacence, à la distance ou au routage. Ce document traite cependant de problèmes d'intérêt plus généraux tels que l'étude de bornes sur la densité de graphes, de la VC-dimension de familles d'ensembles, ou de propriétés métriques et structurelles.Nous établissons dans un premier temps des bornes supérieures sur la densité des sous-graphes de produits cartésien de graphes, puis des sous-graphes de demi-cubes. Pour ce faire, nous définissons des extensions du paramètre classique de VC-dimension. De ces bornes sur la densité, nous déduisons des bornes supérieures sur la longueur des étiquettes attribuées par un schéma d'adjacence à ces deux familles de graphes.Dans un second temps, nous nous intéressons à des schémas de distance et de routage pour deux familles importantes de la théorie métrique des graphes: les graphes médians et les graphes pontés. Nous montrons que la famille des graphes médians, sans cube, avec n sommets, admet des schémas de distance et de routage utilisant des étiquettes de O(\log^3 n). Ces étiquettes sont décodées en temps constant pour calculer, respectivement, la distance exacte entre deux sommets, ou le port vers un sommet rapprochant une source d'une destination. Nous décrivons ensuite un schéma de distances 4-approchées pour la famille des graphes pontés, sans K_4, avec n sommets, utilisant des étiquettes de O(\log^3 n) bits. Ces dernières peuvent être décodées en temps constant pour obtenir une valeur entre la distance exacte et quatre fois celle-ci.Constructing labeling schemes supporting adjacency, distance or routing queries constituted the initial motivation of most of the results of this document. However, this manuscript concerns problem of more general interest such as bounding the density of graphs, studying the VC-dimension of set families, or investigating on metric and structural properties of graphs. As a first contribution, we upper bound the density of the subgraphs of Cartesian products of graphs, and of the subgraphs of halved-cubes. To do so, we extend the classical notion of VC-dimension (already used in 1994 by Haussler, Littlestone, and Warmuth to upper bound the density of the subgraphs of hypercubes). From our results, we deduce upper bounds on the size of labels used by an adjacency labeling scheme on these graph classes. We then investigate on distance and routing labeling schemes for two important families of metric graph theory: median graphs and bridged graphs. We first show that the class of cube-free median graphs on n vertices enjoys distance and routing labeling schemes both using labels of O(\log^3 n) bits. These labels can be decoded in constant time to respectively return the exact distance between two vertices, or a port to take from a source vertex in order to get (strictly) closer to a target one. We then describe an approximate distance labeling scheme for the family of K_4-free bridged graphs on n vertices. This scheme also uses labels of size O(\log^3 n) that can be decoded in constant time to return a value of at most four time the exact distance between two vertices
Dendropaemon (Coprophanaeoides) furtadoi Genier & Arnaud, new species
No full text5. Dendropaemon (Coprophanaeoides) furtadoi Génier & Arnaud, new species (Figs. 5, 48– 49, 156) Type locality. Diamantino, Mato Grosso, Brasil. Diagnosis. Differs from nearly all other species in the genus by its long elytral pilosity combined with the sharply carinate lateral edge of the pronotal lateral depressions. The much less pilose dorsum, especially the nearly glabrous eighth elytral interval will separate D. furtadoi from D. pilosissimus and the much less heavily punctate pronotal disc will separate it from D. carinifer. From its sister species, D. cribrosus, the straight clypeal edge on each side of the clypeal teeth combined with the distinctly anteriorly convergent pronotal lateral edges and less defined elytral striae will set it apart. Description. Male holotype (Fig. 5). Body. Body large, length 15.0 mm, maximum width 8.0 mm; body subrectangular in dorsal view; dorsum narrowly flat. Color. Dorsal surface dark brown to black, glossy, with green metallic sheen; head black along anterior edge of clypeus, metallic green on remaining surface; pronotum with green metallic sheen except for anteromedian carina, on anterior portion of disc and surface adjacent to lateral fossae; elytra with uniform green metallic sheen; ventrum with faint greenish and coppery metallic sheen; pygidium with green metallic sheen; legs with coppery and greenish metallic sheen on femora and tibiae. Head. Clypeus gena arcuate, clypeus straight between clypeogenal junction and lateral emargination of clypeal teeth, anterior portion upturned; clypeal teeth acutely triangular; clypeal median emargination v-shaped, clypeal edge acutely notched on external side of each clypeal tooth, clypeal teeth ventral surface lacking carina, clypeal margin ill-defined, lacking sharp carina posteriorly, clypeal surface with transverse blunt rugulae anteriorly and small setiferous tubercles posteriorly; clypeogenal suture well-defined, bluntly carinate internally; genal surface with small setiferous tubercles, lacking distinct transverse carina, simply convex; clypeofrontal carina rather low, approximately 4 times wider than high, straight in dorsal view, simply carinate, clypeofrontal carina apical edge slightly trilobate in frontal view; eyes large in dorsal view, interocular ratio 4.0. Pronotum. Pronotum transverse in dorsal view, pronotal width/length ratio 1.6; disc of pronotum minutely punctate basally with large confluent setiferous puncture medially changing into dense squamose and setiferous rugulae anteriorly, with an ill-defined shallow longitudinal depression on posterior half; pronotal anterior margin only slightly wider and flat lateral to eye; anterior portion with a tri-sinuous carina, carina produced into a tubercle medially; anterior angles surface finely granulate, similar to lateral margin along posterior edge of anterior margin; lateral fossae oval, bordered laterally by a sharp carina and anteriorly by a blunt tubercle; lateral portions strongly explanate; pronotal basal fossae ill-defined, slightly concave; posterior margin well-defined and crenulate, with several long setae. Elytra. Elytra approximately as long as wide in dorsal view, elytral combined width/length ratio 1.2; elytral base distinctly marginate; elytral striae 1–4 moderately wide basally, narrower and ill-defined on posterior half, evenly impressed throughout, elytral striae 5 similar to 4 on disc, strial punctures fine, well-defined and setiferous, adjacent strial edge feebly encroaching on interval, stria 1 weakly impressed apically, going straight to elytral apical margin; interstriae slightly convex, minutely punctate and with few larger setiferous punctures along striae, surface glossy. Thoracic sterna. Proepisternal carina absent; metasternal median lobe angularly produced anteromedially, ventral ridge well-defined, y-shaped. Legs. Profemur posterior surface slightly but distinctly convex and glabrous internally, posterointernal margin rather thin, uneven, internal edge rather wide, with a contiguous row of setae along anterointernal edge and few scattered long setae on anterior half, remaining surface with irregular ill-defined punctures and glossy. Protibia with four teeth on lateral edge; internal basal angle lobate; anterior surface with long aligned row of setae internally, surface glossy or feebly microsculptured between punctures; posterior surface with some ill-defined irregular punctures externally to median carina, surface glossy between punctures, with a single interrupted setal row along lateral teeth. Mesofemur angularly produced on anterointernal edge apically. Mesotibia rather short, gradually widening toward apex in anterior view; anteroapical edge slightly sinuate in anterior view, anteroapical row of setae complete; apicoanterior edge circularly indented internally; external edge more or less rounded, with several large elongate setiferous punctures. Mesotarsus similar in shape to metatarsus, 3 -segmented, first segment moderately elongate, approximately two times as long as wide at apex. Metafemur internal edge nearly straight and lateral edge arcuate, lacking distinct depressed area anterointernally before apex, apicoposterior edge unmodified, anterior surface with a well-defined sulcus on more than half the length. Metatibia moderately slender, slightly widening toward apex in anterior view, anterior surface with distinct row of setae, surface glossy, metatibial posterior surface flat between longitudinal row of setae and lateral edge, with ill-defined microsculpture. Metatarsus 3 -segmented, first segment moderately elongate, approximately two times as long as wide at apex, with anterointernal carina well defined and almost reaching apical edge. Abdominal sternites. Sternites 3–6 longitudinally flat; sternites 4–6 with 1–3 unaligned rows of setae laterally, narrowly glabrous on segment 4 and with a single row of setae medially on segments 5–6; sternite 7 approximately longitudinally flat medially, shorter than segment 6 along midline; pygidium minutely punctate on disc. Male genitalia (Figs. 48–49). Parameres simply rounded apically in dorsal view; surface smooth, glossy apically. Measurements (1 male). Length: 15.0 mm. Primary type data. Holotype male (CEMT): [BRASIL: MT/ Diamantino/ X. 1984 / E. Furtado]; [WORLD / SCARAB./ DATABASE/ WSD00016761]; [HOLOTYPE / Dendropaemon / furtadoi n.sp. / Génier & Arnaud, 2014]. Material examined. Primary type only. Etymology. Furtadoi, a patronym in honor of Eurides Furtado of Diamantino (Mato Grosso) who was very hospitable during a visit of one of the author (FG) and also the collector of the only known specimen of this species. Natural history. Unknown. Remarks. Female and variation unknown. In addition to the characters mentioned in the diagnosis, this species also differs in having the lateral pronotal fossae bordered anteriorly by a much larger tubercles and the posterior pronotal margin is twice as wide in posterior view as in D. cribrosus. Because a single male specimen of this species is known it is difficult to assess if this is due to the allometric scaling.Published as part of François Génier & Patrick Arnaud, 2016, Dendropaemon Perty, 1830: taxonomy, systematics and phylogeny of the morphologically most derived phanaeine genus (Coleoptera: Scarabaeidae, Scarabaeinae, Phanaeini) in Zootaxa 4099 (1) on pages 14-15, DOI: 10.11646/zootaxa.4099.1.1, http://zenodo.org/record/26827
- …
