Handling Spatial Relations in Logical Concept Analysis to Explore Geographical Data ⋆

Abstract. Because of the expansion of geo-positioning tools and the democratization of geographical information, the amount of geo-localized data that is available around the world keeps increasing. So, the ability to efficiently retrieve informations in function of their geographical facet is an important issue. In addition to individual properties such as position and shape, spatial relations between objects are an important criteria for selecting and reaching objects of interest: e.g., given a set of touristic points, selecting those having a nearby hotel or reaching the nearby hotels. In this paper, we propose Logical Concept Analysis (LCA) and its handling of relations for representing and reasoning on various kinds of spatial relations: e.g., Euclidean distance, topological relations. Furthermore, we present an original way of navigating in geolocalized data, and compare the benefits of our approach with traditional Geographical Information Systems (GIS).

Exploring a Geographical Dataset with GEOLIS

International audienceGeographical data are mainly structured in layers of information. However, this model of organisation is not convenient for navigation inside a dataset, and so limits geographical data exploration to querying. We think information retrieval could be made easier in GIS by the introduction of a navigation based on geographical object properties. For this purpose, we propose a prototype, GEOLIS1, which tightly combines querying and navigation in the search process of geographical data. GEOLIS relies on Logical Information Systems (LIS), which are based on Formal Concept Analysis (FCA) and logics. In this paper, we detail data organisation and navigation process in GEOLIS. We also present the results of an experimentation led on a real dataset

La nouvelle école de philologie romane et sa perception de la littérature médiévale

Au tournant des années 1860 apparaît en France, préparée par les travaux d’érudits tels que Raynouard, Fauriel, Guessard et Paulin Paris, et formée également à l’école de la science allemande, une nouvelle école de philologie romane qui va s’imposer et se doter de ses propres organes, avec la Revue critique en 1865, la Romania en 1872 et la Société des anciens textes français, fondée en 1875 et qui édite un bulletin annuel. Les chefs de file de cette nouvelle école sont les deux directeurs de..

Joseph Bédier dans la chaîne des générations de médiévistes

Cet article traite de la transmission des compétences scientifiques et des positions de prestige dans les grandes institutions du monde académique parmi les générations antérieure, contemporaine et postérieure à Joseph Bédier, qui s’est taillé une réputation de premier plan grâce à une filiation symbolique envers Gaston Paris. Notre visée n’est pas ici de brosser un historique approfondi de ces questions, mais d’apporter quelques éclairages au travers de témoignages glanés dans la correspondance échangée entre Gaston Paris et Paul Meyer. Après le « règne des paléographes » devait venir, selon Bédier, le temps des « brillantes synthèses » – temps qui commence avec lui-même et qui culminera sans doute dans la période 1960-2000. Il se pourrait qu’aujourd’hui soit venu le temps des études ‘transversales’ et d’un intérêt accru pour un Moyen-Âge barbare et païen.</p

Vivre une métaphore : écritures anglo-saxonnes du voyage en mer au viiie siècle

Revisitant la question des origines du pèlerinage, des publications récentes ont rappelé qu’aux yeux des contemporains les premiers voyages religieux relevaient plutôt de l’expression d’une forme particulière de monachisme que d’une pratique de dévotion caractérisée par des rites et un réseau de destinations fermement institués. En examinant les sources du corpus des « Vies missionnaires », nous nous efforçons ici de montrer que les voyageurs religieux anglo-saxons des viie et viiie siècles concevaient encore la peregrinatio pro Deo comme cette recherche d’un renoncement au monde matériel par le mouvement physique réel. La nécessité de justifier cette forme de dévotion, trop proche de l’errance des moines dénoncée par la Règle bénédictine, favorisa le recours au thème littéraire du voyage sur la mer, susceptible de décourager les critiques stigmatisant l’immoralité du genre de vie mené par les moines errants dans le monde séculier. L’aptitude du motif de la traversée maritime à se fondre dans la métaphore du chrétien-voyageur s’ajouta à une lecture « missionnaire » de l’histoire du peuple des Angles pour faire d’un voyage maritime initial une condition nécessaire de ce qui pouvait être considéré comme une pérégrination légitime. Ce thème littéraire, délaissé par l’hagiographie continentale au siècle suivant, imprima pourtant sa marque sur l’historiographie, et peut-être aussi sur la littérature, de la Bretagne insulaire.While re-examining the questions of the origins of pilgrimage, recent publications suggested that contemporary observers considered the earliest religious travels more as another form of monasticism than as a religious practice characterized by a cluster of definite rituals and a network of distinct holy places. In this essay, using Ian Wood’s work on missionary hagiography, we will argue that Anglo-Saxon religious travellers from the seventh and eighth centuries still considered the peregrinatio pro Deo as the pursuit of withdrawal from the material world through physical movement. In order to justify this particular kind of religious devotion, which was, to many extents, too close to the kind of wandering monasticism denounced by the Benedictine Rule, authors used and developed the literary theme of travel by water, which could discourage criticism of the corrupting way of life lived by wandering monks within the secular world. The matching of the sea travel theme with the metaphor of the Christian as a traveller added to a “missionary” conception of the gens Anglorum’s history in establishing initial maritime journey as a necessary pre-condition of what could be properly considered as a peregrinatio by contemporary authors. The topic of water travel was comparatively neglected by continental authors of later missionary Lives. Nonetheless, it stamped its mark on early medieval Britain’s historiography, and also, maybe, on its literature

Bessel bridges decomposition with varying dimension. Applications to finance

We consider a class of stochastic processes containing the classical and well-studied class of Squared Bessel processes. Our model, however, allows the dimension be a function of the time. We first give some classical results in a larger context where a time-varying drift term can be added. Then in the non-drifted case we extend many results already proven in the case of classical Bessel processes to our context. Our deepest result is a decomposition of the Bridge process associated to this generalized squared Bessel process, much similar to the much celebrated result of J. Pitman and M. Yor. On a more practical point of view, we give a methodology to compute the Laplace transform of additive functionals of our process and the associated bridge. This permits in particular to get directly access to the joint distribution of the value at t of the process and its integral. We finally give some financial applications to illustrate the panel of applications of our results

On the use of advanced logic programming languages

Computational Linguistics and Logic Programming have strong connections, but the former uses concepts that are absent from the most familiar implementations of the latter. We advocate that a Logic Programming language needs not feature the Computational Linguistics concepts exactly, it must only provide a logical way of dealing with them. We focus on the manipulation of higher-order terms and the logical handling of context, and we show that the advanced features of \PII\ and \LP\ are useful for dealing with these concepts. Higher-order terms are native in \LP, and \PII's infinite trees provide a handy data-structure for manipulating them. The formulas language of \LP\ can be transposed in the Logic Grammar realm to allow for a logical handling of context

Assessing the Impact of Bycatch on Dolphin Populations: The Case of the Common Dolphin in the Eastern North Atlantic

Fisheries interactions have been implicated in the decline of many marine vertebrates worldwide. In the eastern North Atlantic, at least 1000 common dolphins (Delphinus delphis) are bycaught each year, particularly in pelagic pair-trawls. We have assessed the resulting impact of bycatch on this population using a demographic modeling approach. We relied on a sample of females stranded along the French Atlantic and western Channel coasts. Strandings represent an extensive source of demographic information to monitor our study population. Necropsy analysis provided an estimate of individual age and reproductive state. Then we estimated effective survivorship (including natural and human-induced mortality), age at first reproduction and pregnancy rates. Reproductive parameters were consistent with literature, but effective survivorship was unexpectedly low. Demographic parameters were then used as inputs in two models. A constant parameter matrix proposed an effective growth rate of −5.5±0.5%, corresponding to the current situation (including bycatch mortality). Subsequently, deterministic projections suggested that the population would be reduced to 20% of its current size in 30 years and would be extinct in 100 years. The demographic invariant model suggested a maximum growth rate of +4.5±0.09%, corresponding to the optimal demographic situation. Then, a risk analysis incorporating Potential Biological Removal (PBR), based on two plausible scenarii for stock structure suggested that bycatch level was unsustainable for the neritic population of the Bay of Biscay under a two-stock scenario. In depth assessment of stock structure and improved observer programs to provide scientifically robust bycatch estimates are needed. Effective conservation measures would be reducing bycatch to less than 50% of the current level in the neritic stock to reach PBR. Our approach provided indicators of the status and trajectory of the common dolphin population in the eastern North Atlantic and therefore proved to be a valuable tool for management, applicable to other dolphin populations

A Comprehensive Survey of Pelagic Megafauna: Their Distribution, Densities, and Taxonomic Richness in the Tropical Southwest Indian Ocean

The distribution and density of pelagic megafauna (marine mammals, seabirds, elasmobranches, and sea turtles) are important indicators of marine biodiversity, reflecting the condition of the underlying ecosystems. A dedicated aerial survey was conducted in the tropical Southwest Indian Ocean to map their distribution, the taxonomic diversity, and to estimate their densities to serve as a baseline for the area. This large survey across three ecological sub-regions revealed contrasting spatial distributions: maps of taxonomic richness of marine mammals and seabirds revealed different “hotspots” in the area. Densities were estimated for eight cetacean taxa with small and large Delphininae, or small Globicephalinae dominating, and for seven seabird taxa, with terns and noddies dominating. At the community level, the Southwest Indian Ocean megafauna was structured by the marine environment with strong differences between the Mozambique Channel and the Mascarene Islands, or between shelf and slope/oceanic habitats. Our results illustrate how multi-taxa aerial surveys are relevant and cost-effective monitoring tools for marine megafauna, allowing a community-wide approach