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École Normale Supérieure

Academic institutioneurope · fr
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Research library318linked papers
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Selected work

Representative Papers

Querying Inconsistent Prioritized Data with ORBITS: Algorithms, Implementation, and Experiments (Extended Abstract)

Feb 16, 2022Description Logics

This paper addresses inconsistent-tolerant query answering over prioritized knowledge bases—comprising logical theories, factual databases, and priority relations among conflicting facts. We systematically support query evaluation under three classical semantics—AR (cautious), IAR (intersection of all repairs), and brave—over two classes of optimal repair models: Pareto-optimal and completion-based repairs. Our key contribution is the first unified SAT encoding framework capable of handling arbitrary priority relations, enabling joint modeling and efficient solving for both repair classes and all three semantics. Based on this encoding, we implement ORBITS, a novel reasoning system. Experimental results demonstrate that ORBITS significantly outperforms baseline approaches across all semantics, highlighting the critical impact of semantic choice and solving strategy on performance. The work establishes a new paradigm for practical reasoning over inconsistent prioritized knowledge bases.

18 citationsRead paper

Deterministic Concurrency: A Clock-Synchronised Shared Memory Approach

Apr 16, 2018European Symposium on Programming

Concurrent programming faces a fundamental tension between expressiveness and determinism; conventional shared-memory models suffer from schedule-dependent behavior and non-reproducible outputs due to destructive updates. Method: This paper introduces Clock-Synchronized Memory (CSM), the first shared-memory abstraction that guarantees deterministic semantics for general-purpose concurrent programs—extending beyond the restricted primitives (e.g., registers, signals) supported in traditional synchronous programming (SP). Grounded in the formal mathematical semantics of SP, we design CSM memory primitives, a clock-synchronization protocol, and rigorously defined access rules, ensuring full compatibility with existing SP compilation and verification toolchains. Results: Experiments demonstrate that CSM significantly enhances expressiveness, modularity, and code reusability of concurrent programs while preserving formal verifiability. It provides a theoretically sound and practically deployable deterministic concurrency infrastructure for safety-critical systems.

13 citationsRead paper

Balanced-chromatic number and Hadwiger-like conjectures

Aug 02, 2023arXiv.org

This work addresses the extension of Hadwiger’s conjecture to signed graphs. It introduces the *balanced chromatic number*—the minimum number of vertex subsets required such that no subset induces a negative cycle—as the central combinatorial tool. By establishing a quantitative relationship between the balanced chromatic number and the existence of a ( ilde{K}_t) subdivision, the authors prove an upper bound of (O(t^2)), specifically (frac{79}{2}t^2). They formulate and rigorously prove the *signed-graph analogue of Hadwiger’s conjecture*, demonstrating its equivalence to the classical conjecture. Furthermore, they generalize Kawarabayashi’s result on odd minors to the signed-graph setting and uncover a deep connection between the balanced chromatic number and the odd Hadwiger conjecture. The work unifies structural coloring, minor theory, and subdivision analysis for signed graphs, providing a novel framework for Hadwiger-type problems in signed graph theory.

6 citationsRead paper

An Anytime Algorithm for Good Arm Identification

Oct 16, 2023arXiv.org

This paper studies the Good-Arm Identification (GAI) problem in stochastic multi-armed bandits—identifying arms whose expected rewards exceed a given threshold at any time. To address the lack of unified solutions across fixed-budget and anytime recommendation settings, we propose APGAI, the first parameter-free, truly anytime adaptive sampling algorithm for GAI. Its key contributions are threefold: (i) it is the first GAI algorithm achieving both anytime validity and parameter independence; (ii) we theoretically prove that its adaptive sampling strategy significantly outperforms uniform sampling in detecting the “no-good-arm” scenario; and (iii) we derive tight anytime upper bounds on both error probability and sampling complexity. APGAI integrates confidence-interval estimation, an anytime stopping rule, stochastic bandit analysis under random time horizons, and an empirical Bayes–inspired decision heuristic. Extensive experiments on synthetic and real-world datasets validate its efficiency, robustness, and theoretical guarantees.

4 citations1 influentialRead paper

The feasibility of multi-graph alignment: a Bayesian approach

Feb 24, 2025

This work establishes the statistical feasibility boundary for random multi-graph alignment, deriving the first rigorous phase transition thresholds under both Gaussian and sparse Erdős–Rényi (ER) models. For the Gaussian model, we prove a sharp information-theoretic threshold for exact alignment: above it, exact recovery is achievable with high probability; below it, even partial alignment is statistically impossible. For the sparse ER model, we rigorously characterize the critical edge density beyond which partial alignment becomes statistically infeasible, and conjecture that nontrivial partial alignment is attainable above this threshold. Methodologically, we develop the first general Bayesian estimation framework applicable to metric spaces, integrating information-theoretic analysis, random graph theory, and phase transition analysis. Our core contribution is a “all-or-nothing” solvability criterion for multi-graph alignment—delineating precise conditions under which alignment is either statistically feasible or fundamentally impossible—thereby providing a foundational theoretical basis for high-dimensional structural inference.

2 citationsRead paper
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