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On the Broadcast problem for mobile agents in dynamic networks
No full textInternational audienceWe study the standard communication problem of broadcast for mobile agents moving in a network, where a single agent called source, has to transmit a vital information to all other agents in the network. The agents move autonomously in the network and can communicate with other agents only when they meet at a node. Previous studies of this problem were restricted to static networks while, in this paper, we consider the problem in dynamic networks modelled as an evolving graph. The dynamicity of the graph is unknown to the agents; in each round an adversary selects which edges of the graph are available, and an agent can choose to traverse one of the available edges adjacent to its current location. The only restriction on the adversary is that the subgraph of available edges in each round must span all nodes; in other words the evolving graph is constantly connected. The agents have global visibility allowing them to see the location of all agents in the graph and move accordingly. Depending on the topology of the underlying graph, we determine the minimum value of k > 0, such that the broadcast from a source agent to k other agents can be solved in dynamic networks. While k = 2 agents are sufficient for ring networks, much larger teams of agents are necessary for denser graphs such as grid graphs and hypercubes, and finally for complete graphs of n nodes k ≥ n−2 agents are necessary and sufficient. We show lower bounds on the number of agents and provide algorithms for solving broadcast using the minimum number of agents, for various topologies. These results show how the connectivity of the underlying graph affects the communication capability of a team of mobile agents in constantly connected dynamic networks
Characterising memory in infinite games
No full textInternational audienceThis paper is concerned with games of infinite duration played over potentially infinite graphs. Recently, Ohlmann (TheoretiCS 2023) presented a characterisation of objectives admitting optimal positional strategies, by means of universal graphs: an objective is positional if and only if it admits well-ordered monotone universal graphs. We extend Ohlmann's characterisation to encompass (finite or infinite) memory upper bounds.We prove that objectives admitting optimal strategies with ε-memory less than m (a memory that cannot be updated when reading an ε-edge) are exactly those which admit well-founded monotone universal graphs whose antichains have size bounded by m. We also give a characterisation of chromatic memory by means of appropriate universal structures. Our results apply to finite as well as infinite memory bounds (for instance, to objectives with finite but unbounded memory, or with countable memory strategies).We illustrate the applicability of our framework by carrying out a few case studies, we provide examples witnessing limitations of our approach, and we discuss general closure properties which follow from our results.This document contains hyperlinks. Each occurrence of a notion is linked to its definition. On an electronic device, the reader can click on words or symbols (or just hover over them on some PDF readers) to see their definition.</div
Seasonal and spatial variability of dissolved black carbon in the Red River delta (North Vietnam)
No full textInternational audienceDissolved black carbon (DBC) is a key component of the global carbon cycle, yet its seasonal dynamics and river-to-sea transport remain poorly understood, particularly in Southeast Asia where anthropogenic pressures are intense. This study investigates the spatial and seasonal variability of DBC along with dissolved organic matter (DOM) in the main branch of the Red River (North Vietnam) based on three sampling campaigns conducted in March (dry season), June (early wet season), and September 2023 (late wet season). DBC concentrations increased from 29 μg C L⁻ 1 in March to 66 μg C L⁻ 1 in September, following rainfall-driven inputs. This seasonal pattern was accompanied by changes in DOM quality, as inferred from optical indices: higher SUVA₂₅₄ (specific UV absorbance at 254 nm), a CDOM( 350) (absorption coefficient of chromophoric DOM at 350 nm), and HIX (humification index) in September indicated more terrestrial and humified material, while higher BIX (biological index) in March suggested a higher contribution of fresher, autochthonous DOM. Spatial trends showed a downstream decrease in DBC in June, likely due to abiotic degradation (particularly photodegradation) and dilution. This contrasted with the increasing concentrations from Hanoi to the estuary in March and September, which may be linked to local inputs during dry-season groundwater dynamics and rainfall. DOM optical indices support a contribution of low-DBC groundwater near Hanoi in March. Estimated DBC fluxes at the estuary reached up to 20.7 Gg yr⁻ 1 , representing 0.11% of the global riverine DBC flux to the ocean during the wet season. These results emphasize the role of tropical rivers as dynamic conveyors of combustion-derived carbon, where seasonality and local processes, such as rainfall, photodegradation, and groundwater inflow, strongly shape DBC transport from land to sea
Ground and Excited State Aromaticity in Azulene‐Based Helicenes
No full textInternational audienceAbstract Electron delocalization is studied in the ground singlet and first excited triplet states of azulene‐containing helicenes. After showing that the compounds we study can be synthesized, we show that they exhibit a charge separation in the ground state, which does not appear in their triplet excited state. Then, magnetically induced properties (IMS3D and ACID) and electron density decomposition methods (EDDB) are used to rationalize aromaticity in these systems. For azulene‐based helicenes larger than a critical size, that is, for more than six fused cycles, unexpected aromatic delocalization circuits appear. This feature is understood via the decomposition of the wavefunction on sets of carefully chosen local electronic structures and fragment orbital diagrams
A Booklet of I-BioLex posters
No full textLivret des posters réalisés dans le cadre du projet ANR I-BioLex (2021-2025)From 1st January 2021 to 31 October 2025, the I-BioLex members and other colleagues have produced 26 posters that have been presented in International and European congresses in France and abroad. These posters are parts of the analysis conducted on fragmentation (division or segmentation), and defragmentation (gathering together, connecting or ‘harmonising’) of the European law on Biomedical innovations, regarding biological medicines and their subcategories, Advanced Therapy Medicinal Products and their subcategories, and orphan medicines. They relate to the various topics presented below in the table of contents
The logarithmic memristor-based Bayesian machine
No full textInternational audienceThe demand for explainable and energy-efficient artificial intelligence (AI) systems for edge computing has led to growing interest in electronic systems dedicated to Bayesian inference. Traditional designs of such systems often rely on stochastic computing, which offers high energy efficiency but suffers from latency issues and struggles with low-probability values. Here, we introduce the logarithmic memristor-based Bayesian machine, an innovative design that leverages the unique properties of memristors and logarithmic computing as an alternative to stochastic computing. We present a prototype machine fabricated in a hybrid CMOS/hafnium-oxide memristor process. We validate the versatility and robustness of our system through experimental validation and extensive simulations in two distinct applications: gesture recognition and sleep stage classification. The logarithmic approach simplifies the computational model by converting multiplications into additions and enhances the handling of low-probability events, which are crucial in time-dependent tasks. Our results demonstrate that the logarithmic Bayesian machine achieves superior performance in terms of accuracy and energy efficiency compared to its stochastic counterpart, particularly in scenarios involving complex probabilistic models. This approach enables the development of energy-efficient and reliable AI systems for edge devices
Complexity of Łukasiewicz Modal Probabilistic Logics
No full textInternational audienceModal probabilistic logics provide a framework for reasoning about probability in modal contexts, involving notions such as knowledge, belief, time, and action. In this paper, we study a particular family of these logics, extending the modal Łukasiewicz many-valued logic. These logics are shown to be capable of expressing nuanced probabilistic concepts, including upper and lower probabilities. Our main contribution is a PSPACE-completeness result for two variants of the local consequence problem, providing a precise computational characterisation.</div
The ANTARES detector: two decades of neutrino searches in the Mediterranean Sea
No full textInternational audienceInterest for studying cosmic neutrinos using deep-sea detectors has increase after the discovery of a diffuse flux of cosmic neutrinos by the IceCube collaboration and the possibility of wider multi-messenger studies with the observations of gravitational waves. The ANTARES detector was the first neutrino telescope in seawater, operating successfully in the Mediterranean Sea for more than a decade and a half. All challenges related to the operation in the deep sea were accurately addressed by the collaboration. Deployment and connection operations became smoother over time; data taking and constant re-calibration of the detector due to the variable environmental conditions were fully automated. A wealth of results on the subject of astroparticle physics, particle physics and multi-messenger astronomy have been obtained, despite the relative modest size of the detector, paving the way to a new generation of larger undersea detectors. This review summarizes the efforts by the ANTARES collaboration that made the possibility to operate neutrino telescopes in seawater a reality and the results obtained in this endeavor