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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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DTSTART:20250330T010000
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DTSTART:20251026T010000
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BEGIN:VEVENT
DTSTART;TZID=Europe/Paris:20250304T104500
DTEND;TZID=Europe/Paris:20250304T114500
DTSTAMP:20260421T122920
CREATED:20250204T142355Z
LAST-MODIFIED:20250204T142355Z
UID:11793-1741085100-1741088700@www.greyc.fr
SUMMARY:Séminaire algorithmique : Vincent Jugé (LIGM\, Univ. G. Eiffel\, Paris Est)\, « Write-efficient updates for AVL trees »
DESCRIPTION:Balanced binary search trees are a common data structure for implementing ordered sets\, with three kinds of queries: checking whether a given value belongs to the set\, inserting a value\, and deleting a value; the two latter queries require updating the data structure. Some implementations\, like red-black trees or weak AVL trees\, allow efficient update procedures\, which run in a top-down way and require an amortized constant number of write operations per update query; by contrast\, AVL trees still require bottom-up updating procedures\, which may require a logarithmic number of write operations per query. \nWe will present recent algorithms for updating AVL trees that bridge this gap: they run in a top-down way and/or require only an amortized constant number of write operations per update query; most of the presentation will be devoted to the latter aspect.
URL:https://www.greyc.fr/event/seminaire-algorithmique-vincent-juge-ligm-univ-g-eiffel-paris-est-write-efficient-updates-for-avl-trees/
LOCATION:Sciences 3- S3 351
CATEGORIES:Amacc,General,News,Séminaire Algo
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DTSTART;TZID=Europe/Paris:20250305T140000
DTEND;TZID=Europe/Paris:20250305T150000
DTSTAMP:20260421T122920
CREATED:20250224T143502Z
LAST-MODIFIED:20250224T143502Z
UID:11804-1741183200-1741186800@www.greyc.fr
SUMMARY:Laura Luzzi - Finite blocklength secrecy analysis of polar and Reed-Muller codes in binary erasure wiretap channels
DESCRIPTION:Physical layer security aims to exploit the randomness of noisy channels in order to enhance security through coding and signal processing techniques. Unlike cryptography\, it does not place any limitations on the adversary’s computational power\, but relies on an asymmetry in the channel quality between the legitimate users and the adversary. In this talk\, we focus on the wiretap channel model\, where a legitimate transmitter and receiver communicate in the presence of an eavesdropper who observes a degraded version of the receiver’s outputs. For this model\, secrecy can be measured in terms of mutual information leakage\, or alternatively in terms of the average variational distance between output distributions corresponding to different confidential messages. \nMotivated by IoT applications that require short packets or low latency\, we focus on the performance of wiretap codes in finite blocklength. We consider a simple channel model where the main channel is noiseless and the eavesdropper’s channel is a binary erasure channel\, and provide lower bounds for the achievable secrecy rates of polar and Reed-Muller codes. We show that under a total variation secrecy metric\, Reed-Muller codes can achieve secrecy rates very close to the optimal second order coding rates.
URL:https://www.greyc.fr/event/laura-luzzi-finite-blocklength-secrecy-analysis-of-polar-and-reed-muller-codes-in-binary-erasure-wiretap-channels/
LOCATION:Sciences 3- S3 351
CATEGORIES:General,News,Safe,Séminaire Cryptologie et sécurité
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