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X-WR-CALNAME:GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen
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X-WR-CALDESC:évènements pour GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen
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TZID:Europe/Paris
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DTSTART:20260329T010000
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DTSTART:20261025T010000
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DTSTART;TZID=Europe/Paris:20260505T104500
DTEND;TZID=Europe/Paris:20260505T114500
DTSTAMP:20260615T163729
CREATED:20260526T120349Z
LAST-MODIFIED:20260526T120349Z
UID:12123-1777977900-1777981500@www.greyc.fr
SUMMARY:Séminaire Algorithmique : « From Elastic Degenerate Strings to Full-Text Indexing: Suffix Sorting\, BWT\, and FM-Index Construction and Search »\, Francesco Pio Marino (Univ. Catane\, Italie)
DESCRIPTION:Elastic degenerate strings provide a flexible framework for representing sequences with structured variability\, generalizing classical string models while preserving algorithmic tractability. In this talk\, we present a comprehensive framework for indexing such objects\, culminating in the construction of an FM-index that supports efficient pattern matching. \nWe begin by revisiting the notion of elastic degeneracy and its algorithmic implications. We then describe how classical building blocks—suffix sorting\, the Burrows–Wheeler Transform (BWT)\, and wavelet trees—can be extended to this richer setting. In particular\, we outline a linear-time suffix sorting approach based on an adaptation of the DC3 algorithm\, followed by the construction of the BWT and the associated wavelet tree representation. \nFinally\, we show how these components combine into a full FM-index and describe how the classical backward search procedure can be adapted to this setting\, enabling efficient pattern matching over elastic degenerate strings. The resulting framework bridges combinatorial pattern matching and compressed indexing\, opening the way to scalable querying in settings where uncertainty and variability are intrinsic.
URL:https://www.greyc.fr/event/seminaire-algorithmique-from-elastic-degenerate-strings-to-full-text-indexing-suffix-sorting-bwt-and-fm-index-construction-and-search-francesco-pio-marino-univ-catane-italie/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,News,Séminaire Algo
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DTSTART;TZID=Europe/Paris:20260505T110000
DTEND;TZID=Europe/Paris:20260505T120000
DTSTAMP:20260615T163729
CREATED:20260512T080924Z
LAST-MODIFIED:20260512T080924Z
UID:12097-1777978800-1777982400@www.greyc.fr
SUMMARY:Séminaire Image: Kirchhoff Forests: Theory and Applications par Yusuf Yigit Pilavci
DESCRIPTION:Nous aurons le plaisir d’écouter Yusuf Yigit Pilavci \, Postdoc a l’Institut Mines Telecom Nord Europe.\nIl donnera un séminaire IMAGE le mardi 05 mai 2026 à 11h en salle de séminaire F-200. \nTitre : « Kirchhoff Forests: Theory and Applications » \nRésumé : Many machine learning problems involve data structured as graphs\, from social networks and recommendation systems to traffic and biological networks. A key tool for analyzing these graphs is the graph Laplacian\, which captures important structural information but becomes expensive to compute at large scale.\nIn this presentation\, I will introduce a probabilistic tool called Kirchhoff forests for accelerating expensive operations involving graph Laplacians\, such as computing their inverse\, estimating the trace of the inverse\, and estimating effective resistances. This probabilistic method is based on a random process that allows us to generate graph sketches strongly connected to the graph Laplacian through various theoretical guarantees. In turn\, this approach leads to efficient algorithms for applications in graph signal processing and machine learning. \n 
URL:https://www.greyc.fr/event/seminaire-image-kirchhoff-forests-theory-and-applications-par-yusuf-yigit-pilavci/
LOCATION:ENSICAEN – Batiment F – Salle F-200\, 6 Bd Maréchal Juin\, Caen\, 14050\, France
CATEGORIES:General,Image,Seminaire Image
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