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PRODID:-//GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen - ECPv5.7.0//NONSGML v1.0//EN
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X-WR-CALNAME:GREYC UMR CNRS 6072 - Groupe de Recherche en Informatique, Image, et Instrumentation de Caen
X-ORIGINAL-URL:https://www.greyc.fr
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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TZOFFSETFROM:+0100
TZOFFSETTO:+0200
TZNAME:CEST
DTSTART:20260329T010000
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DTSTART:20261025T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260106T104500
DTEND;TZID=Europe/Paris:20260106T114500
DTSTAMP:20260418T201636
CREATED:20251219T084449Z
LAST-MODIFIED:20251219T085309Z
UID:12009-1767696300-1767699900@www.greyc.fr
SUMMARY:Séminaire Algorithmique : « Post-Quantum Public-Key Pseudorandom Correlation Functions for Oblivious Transfer »\, Mahshid Riahinia (ENS Paris et IRIF\, Univ. Paris Cité)
DESCRIPTION:Public-Key Pseudorandom Correlation Functions (PK-PCF) are functions that generate pseudorandom correlated strings. These correlations can then be used to speed up secure computation protocols. Recent works have made significant progress building PK-PCFs using group-based assumptions\, however\, these assumptions do not hold up against quantum attackers. Much less is known about PK-PCFs in the post-quantum regime. In this talk\, I will introduce an efficient lattice-based PK-PCF for oblivious transfer (OT) correlations. At the heart of our result lie several technical contributions that might be of independent interest. In particular\, we introduce the first efficient lattice-based constrained pseudorandom functions for low-degree polynomials\, from a new but natural “secret-power” variant of ring learning with errors (ring-LWE) assumption.
URL:https://www.greyc.fr/event/seminaire-algorithmique-post-quantum-public-key-pseudorandom-correlation-functions-for-oblivious-transfer-mahshid-riahinia-ens-paris-et-irif-univ-paris-cite/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,News,Séminaire Algo
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260113T104500
DTEND;TZID=Europe/Paris:20260113T114500
DTSTAMP:20260418T201636
CREATED:20251219T084652Z
LAST-MODIFIED:20251219T084652Z
UID:12011-1768301100-1768304700@www.greyc.fr
SUMMARY:Séminaire Algorithmique : « Revenge of the 4D: Can 4-dimensional isogenies become practical? »\, Pierrick Dartois (INRIA Rennes)
DESCRIPTION:The devastating attacks against SIDH (Supersingular Isogeny Diffie-Hellman) in 2022 introduced higher-dimensional isogenies as a cryptanalytic tool. As opposed to elliptic curve isogenies\, higher-dimensional isogenies are defined between abelian varieties (which generalize elliptic curves in higher dimension). These isogenies quickly became a powerful constructive tool in cryptography with the introduction of SQIsignHD and FESTA\, followed up by many new isogeny-based cryptographic schemes. \nThe digital signature scheme SQIsignHD\, based on SQIsign was the first scheme to use 4-dimensional isogenies but soon became obsolete when 2-dimensional alternatives were introduced and proposed as a part of the SQIsign NIST post-quantum signatures standard submission. For efficiency reasons\, most isogeny based schemes aiming for practical use rely on isogenies of dimension at most 2\, and it is widely believed in the isogeny community that isogenies of dimension bigger than 2 should be avoided. \nThe recent introduction of the Pegasis algorithm to compute the ideal class group action on oriented supersingular elliptic curves without restriction on the ideal has changed this perspective. This algorithm using 4-dimensional isogenies beats all 2-dimensional alternatives. Pegasis can be used as a tool to improve advanced cryptographic schemes that require unrestricted cryptographic group actions and is to be integrated in a NIST post-quantum threshold cryptographic standard submission. 4-dimensional isogenies also appear in the tensor-MIKE key exchange that remains to be implemented. These works make 4-dimensional isogenies more credible while algorithms to compute them are still making progress.
URL:https://www.greyc.fr/event/seminaire-algorithmique-revenge-of-the-4d-can-4-dimensional-isogenies-become-practical-pierrick-dartois-inria-rennes/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,Séminaire Algo
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260120T104500
DTEND;TZID=Europe/Paris:20260120T114500
DTSTAMP:20260418T201636
CREATED:20251219T085001Z
LAST-MODIFIED:20260107T104620Z
UID:12013-1768905900-1768909500@www.greyc.fr
SUMMARY:Séminaire Algorithmique : « Eunoia: A Framework for SMT Proof Calculi »\, Hans-Jörg Schurr (Univ. of Iowa\, USA)
DESCRIPTION:Satisfiability Modulo Theories (SMT) solvers combine decision procedures for various theories into a homogeneous automated reasoning framework. They are an indispensable tools to solve formal verification and decision problems. To validate the SMT solver’s responses we can use proof certificates. However\, a major challenge is that different theories and decision procedures use different proof calculi. \nWe will discuss the novel Eunoia language which allows SMT developers to define proof rules precisely. The syntax of Eunoia resembles the standard SMT-LIB format. Proofs using Eunoia-defined rules can be checked using the dedicated Ethos proof checker. We specified all proof calculus of the industrial strength SMT solver cvc5 in Eunoia. We will also discuss ongoing efforts to provide a formal and mechanized type system for Eunoia\, and future directions for proof certificates for SMT solvers.
URL:https://www.greyc.fr/event/seminaire-algorithmique-hans-jorg-schurr-univ-of-iowa-usa/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,News,Séminaire Algo
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260122T140000
DTEND;TZID=Europe/Paris:20260122T153000
DTSTAMP:20260418T201636
CREATED:20260106T153328Z
LAST-MODIFIED:20260116T105929Z
UID:12017-1769090400-1769095800@www.greyc.fr
SUMMARY:Séminaire Image : Learning on graphs and hierarchies par Silvio Jamil Ferzoli Guimaraes
DESCRIPTION:Nous aurons le plaisir d’écouter Silvio Jamil Ferzoli Guimaraes\, professeur à la Pontifical Catholic University of Minas Gerais.\nIl donnera un séminaire IMAGE le jeudi 22 janvier 2026 à 14h en salle de séminaire F-200. \nTitre : « Learning on graphs and hierarchies » \nRésumé :  \nHierarchies\, as described in mathematical morphology\, represent nested regions of interest that facilitate high-level analysis and provide mechanisms for coherent data organization. Represented as hierarchical trees\, they have formalisms intersecting with graph theory and applications that can be conveniently generalized. However\, due to the deterministic algorithms\, the multiform representations\, and the absence of a direct way to evaluate the hierarchical structure\, it is hard to insert hierarchical information into a learning framework and benefit from the recent advances in the field. This work aims to create a learning framework that can operate with hierarchical data and is agnostic to the input and the application. The idea is to study ways to transform the data to a regular representation required by most learning models while preserving the rich information in the hierarchical structure. The methods in this study use edge- weighted image graphs and hierarchical trees as input\, evaluating different proposals on the edge detection and segmentation tasks. The model of choice is the Random Forest\, a fast\, inspectable\, scalable method. The experiments demonstrate that it is possible to create a learning framework dependent only on the hierarchical data that performs well in multiple tasks. \nResearchers involved in this topic:\nRaquel Almeida\, Silvio Jamil F. Guimarães\, Laurent Amsaleg\, Ewa Kijak\, Simon Malinowski
URL:https://www.greyc.fr/event/seminaire-image-tba-par-silvio-jamil-ferzoli-guimaraes/
LOCATION:ENSICAEN – Batiment F – Salle F-200\, 6 Bd Maréchal Juin\, Caen\, 14050\, France
CATEGORIES:General,Image,Seminaire Image
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260127T104500
DTEND;TZID=Europe/Paris:20260127T114500
DTSTAMP:20260418T201636
CREATED:20251219T085126Z
LAST-MODIFIED:20260130T101130Z
UID:12015-1769510700-1769514300@www.greyc.fr
SUMMARY:Séminaire Algorithmique : « Data-driven design of logic-based models of biological processes »\, Samuel Pastva (Masaryk Univ. Brno\, Tchéquie)
DESCRIPTION:Modern cell biology generates a treasure trove of experimental data\, allowing us to measure many biochemical processes in individual cells with single-molecule resolution. However\, applying this data to generate explainable predictions is often challenging due to the high number of entities\, interactions\, and environmental factors in question. Systems biology utilizes logic-based explainable models (e.g.\, Boolean networks) to address this challenge. Historically\, many such models were designed manually by domain experts; however\, this approach is not scalable for the modern era\, and new data-driven approaches are needed. \nIn this talk\, I will provide a state-of-the-art overview of methods for developing and analyzing logic-based models that integrate these large\, cutting-edge genomic datasets. First\, we will cover the formalization of biological observations into logical constraints. Specifically\, which formal assumptions can be extracted from biological data and what the limitations of our current measurement techniques are. Then\, I will present methods based on automated reasoning (SAT/SMT/ASP) and symbolic data structures (binary decision diagrams) that allow us to learn formally verified model candidates from these observations. Finally\, because complex systems rarely have a single “best” logic-based model\, we will conclude by discussing how to analyze and refine large ensembles of logic-based models (so-called partially specified Boolean models) that capture the plausible behaviors of a biological system.
URL:https://www.greyc.fr/event/seminaire-algorithmique-samuel-pastva-masaryk-univ-brno-tchequie/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,News,Séminaire Algo
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20260129T140000
DTEND;TZID=Europe/Paris:20260129T150000
DTSTAMP:20260418T201636
CREATED:20260107T091442Z
LAST-MODIFIED:20260122T085131Z
UID:12019-1769695200-1769698800@www.greyc.fr
SUMMARY:Séminaire Image : Comment faciliter l'interaction avec de grandes quantités de données? par Gary Perelman
DESCRIPTION:Nous aurons le plaisir d’écouter Gary Perelman\, MCF CDD au GREYC.\nIl donnera un séminaire IMAGE le jeudi 29 janvier 2026 à 14h en salle de séminaire F-200. \nTitre : « Comment faciliter l’interaction avec de grandes quantités de données? » \nRésumé :  \nL’interaction avec de grandes quantités de données est aujourd’hui omniprésente dans de nombreux domaines\, notamment en analyse de données scientifiques\, en systèmes décisionnels\, en visualisation de données issues de capteurs ou encore dans les applications fondées sur l’intelligence artificielle. Ces contextes se caractérisent par des jeux de données volumineux\, souvent hétérogènes et évolutifs\, que les utilisateurs doivent explorer\, comprendre et manipuler afin de soutenir leurs activités d’analyse et de prise de décision. Du point de vue de l’Interaction Humain-Machine (IHM)\, la manipulation de grands ensembles de données constitue une problématique majeure. Les limitations cognitives humaines\, combinées à la complexité intrinsèque des données\, rendent difficile leur exploration efficace. Les utilisateurs peuvent rapidement être confrontés à une surcharge informationnelle\, à des difficultés de navigation ou à une perte de contexte lors des interactions. De nombreux travaux en IHM et en visualisation de données ont ainsi mis en évidence les enjeux liés au passage à l’échelle des techniques d’interaction et à la compréhension des relations entre éléments de données. Ces enjeux se manifestent différemment selon les dispositifs d’interaction. Sur les systèmes traditionnels clavier-souris\, les interactions indirectes et séquentielles peuvent limiter l’efficacité de la manipulation de données complexes. Sur les dispositifs mobiles\, la faible surface d’affichage impose des compromis importants entre quantité d’information\, lisibilité et précision des interactions. Enfin\, dans les environnements de réalité augmentée et virtuelle\, l’abondance d’informations affichables dans l’espace peut conduire à une surcharge visuelle\, ainsi qu’à une perte du lien entre les données visualisées et leur origine ou leur contexte. Ces constats soulignent le caractère transversal et toujours ouvert de la problématique de l’interaction avec de grandes quantités de données en IHM. Mes travaux de recherche contribuent à répondre à cette problématique en offrant des solutions d’interaction innovantes dans ces multiples domaines visant à faciliter l’interaction avec de grandes quantités de données.
URL:https://www.greyc.fr/event/seminaire-image-tba-par-gary-perelman/
LOCATION:ENSICAEN – Batiment F – Salle F-200\, 6 Bd Maréchal Juin\, Caen\, 14050\, France
CATEGORIES:General,Image,Seminaire Image
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