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51st International Colloquium on Automata, Languages, and Programming, ICALP 2024

作者： Foucaud, Florent Galby, Esther Khazaliya, Liana Li, Shaohua Mc Inerney, Fionn Sharma, Roohani Tale, Prafullkumar Université Clermont Auvergne CNRS Mines Saint-Étienne Clermont Auvergne INP LIMOS Clermont-Ferrand63000 France Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden University of Gothenburg Sweden Technische Universität Wien Austria CISPA Helmholtz Center for Information Security Saarbrücken Germany University of Bergen Norway Indian Institute of Science Education and Research Pune India

ISBN: (纸本)9783959773225

Treewidth serves as an important parameter that, when bounded, yields tractability for a wide class of problems. For example, graph problems expressible in Monadic Second Order (MSO) logic and Quantified SAT or, more generally, Quantified CSP, are fixed-parameter tractable parameterized by the treewidth of the input’s (primal) graph plus the length of the MSO-formula [Courcelle, Information & Computation 1990] and the quantifier rank [Chen, ECAI 2004], respectively. The algorithms generated by these (meta-)results have running times whose dependence on treewidth is a tower of exponents. A conditional lower bound by Fichte, Hecher, and Pfandler [LICS 2020] shows that, for Quantified SAT, the height of this tower is equal to the number of quantifier alternations. These types of lower bounds, which show that at least double-exponential factors in the running time are necessary, exhibit the extraordinary level of computational hardness for such problems, and are rare in the current literature: there are only a handful of such lower bounds (for treewidth and vertex cover parameterizations) and all of them are for problems that are #NP-complete, Σp2-complete, Πp2-complete, or complete for even higher levels of the polynomial hierarchy. Our results demonstrate, for the first time, that it is not necessary to go higher up in the polynomial hierarchy to achieve double-exponential lower bounds: we derive double-exponential lower bounds in the treewidth (tw) and the vertex cover number (vc), for natural, important, and well-studied NP-complete graph problems. Specifically, we design a technique to obtain such lower bounds and show its versatility by applying it to three different problems: Metric Dimension, Strong Metric Dimension, and Geodetic Set. We prove that these problems do not admit 22o(tw) ·nO(1)-time algorithms, even on bounded diameter graphs, unless the ETH fails (here, n is the number of vertices in the graph). In fact, for Strong Metric Dimension, the double-expo

关键词： Parameterization

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Double Averaging and Gradient Projection: Convergence Guarantees for Decentralized Constrained Optimization

arXiv

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arXiv 2022年

作者： Shahriari-Mehr, Firooz Panahi, Ashkan The department of Computer Science and Engineering Chalmers University of Technology Göteborg Sweden

We consider a generic decentralized constrained optimization problem over static, directed communication networks, where each agent has exclusive access to only one convex, differentiable, local objective term and one convex constraint set. For this setup, we propose a novel decentralized algorithm, called DAGP (Double Averaging and Gradient Projection), based on local gradients, projection onto local constraints, and local averaging. We achieve global optimality through a novel distributed tracking technique we call distributed null projection. Further, we show that DAGP can be used to solve unconstrained problems with non-differentiable objective terms with a problem reduction scheme. Assuming only smoothness of the objective terms, we study the convergence of DAGP and establish sub-linear rates of convergence in terms of feasibility, consensus, and optimality, with no extra assumption (e.g. strong convexity). For the analysis, we forego the difficulties of selecting Lyapunov functions by proposing a new methodology of convergence analysis in optimization problems, which we refer to as aggregate lower-bounding. To demonstrate the generality of this method, we also provide an alternative convergence proof for the standard gradient descent algorithm with smooth functions. Finally, we present numerical results demonstrating the effectiveness of our proposed method in both constrained and unconstrained problems. In particular, we propose a distributed scheme by DAGP for the optimal transport problem with superior performance and speed. © 2022, CC BY-SA.

关键词： Convex optimization

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Learning Test-Mutant Relationship for Accurate Fault Localisation

arXiv

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arXiv 2023年

作者： Kim, Jinhan An, Gabin Feldt, Robert Yoo, Shin School of Computing KAIST Daejeon Korea Republic of Dept. of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

Context: Automated fault localisation aims to assist developers in the task of identifying the root cause of the fault by narrowing down the space of likely fault locations. Simulating variants of the faulty program called mutants, several Mutation Based Fault Localisation (MBFL) techniques have been proposed to automatically locate faults. Despite their success, existing MBFL techniques suffer from the cost of performing mutation analysis after the fault is observed. Method: To overcome this shortcoming, we propose a new MBFL technique named SIMFL (Statistical Inference for Mutation-based Fault Localisation). SIMFL localises faults based on the past results of mutation analysis that has been done on the earlier version in the project history, allowing developers to make predictions on the location of incoming faults in a just-in-time manner. Using several statistical inference methods, SIMFL models the relationship between test results of the mutants and their locations, and subsequently infers the location of the current faults. Results: The empirical study on Defects4J dataset shows that SIMFL can localise 113 faults on the first rank out of 224 faults, outperforming other MBFL techniques. Even when SIMFL is trained on the predicted kill matrix, SIMFL can still localise 95 faults on the first rank out of 194 faults. Moreover, removing redundant mutants significantly improves the localisation accuracy of SIMFL by the number of faults localised at the first rank up to 51. Conclusion: This paper proposes a new MBFL technique called SIMFL, which exploits ahead-of-time mutation analysis to localise current faults. SIMFL is not only cost-effective, as it does not need a mutation analyse after the fault is observed, but also capable of localising faults accurately. © 2023, CC BY.

关键词： Location

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SoK: Analysis of Root Causes and Defense Strategies for Attacks on Microarchitectural Optimizations

arXiv

引用

arXiv 2022年

作者： Holtryd, Nadja Ramhöj Manivannan, Madhavan Stenström, Per Department of Computer Science and Engineering Chalmers University of Technology Göteborg Sweden

Microarchitectural optimizations are expected to play a crucial role in ensuring performance scalability. However, recent attacks have demonstrated that microarchitectural optimizations, which were assumed to be secure, can be exploited. Moreover, new attacks surface at a rapid pace limiting the scope of existing defenses. These developments prompt the need to review microarchitectural optimizations with an emphasis on security, understand the attack landscape and the potential defense strategies. We analyze timing-based side-channel attacks targeting a diverse set of microarchitectural optimizations. We provide a framework for analysing non-transient and transient attacks, which highlights the similarities. We identify the four root causes of timing-based side-channel attacks: determinism, sharing, access violation and information flow, through our systematic analysis. Our key insight is that a subset (or all) of the root causes are exploited by attacks and eliminating any of the exploited root causes, in any attack step, is enough to provide protection. Leveraging our framework, we systematize existing defenses and show that they target these root causes in the different attack steps. © 2022, CC BY.

关键词： Network security

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THE EQUIVARIANT MODEL STRUCTURE ON CARTESIAN CUBICAL SETS

arXiv

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arXiv 2024年

作者： Awodey, Steve Cavallo, Evan Coquand, Thierry Riehl, Emily Sattler, Christian Departments of Philosophy and Mathematics Carnegie Mellon University PittsburghPA15213 United States Department of Computer Science and Engineering Chalmers University of Technology University of Gothenburg Göteborg405 30 Sweden Department of Mathematics Johns Hopkins University BaltimoreMD21218 United States Department of Computer Science and Engineering Chalmers University of Technology University of Gothenburg GöteborgS-412 96 Sweden

We develop a constructive model of homotopy type theory in a Quillen model category that classically presents the usual homotopy theory of spaces. Our model is based on presheaves over the cartesian cube category, a well-behaved Eilenberg-Zilber category. The key innovation is an additional equivariance condition in the specification of the cubical Kan fibrations, which can be described as the pullback of an interval-based class of uniform fibrations in the category of symmetric sequences of cubical sets. The main technical results in the development of our model have been formalized in a computer proof assistant. Copyright © 2024, The Authors. All rights reserved.

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Thermodynamic Interpolation: A generative approach to molecular thermodynamics and kinetics

arXiv

引用

arXiv 2024年

作者： Moqvist, Selma Chen, Weilong Schreiner, Mathias Nüske, Feliks Olsson, Simon Department of Computer Science and Engineering Chalmers University of Technology University of Gothenburg GothenburgSE-41296 Sweden Max-Planck-Institute for Dynamics of Complex Technical Systems Magdeburg Germany

Using normalizing flows and reweighting, Boltzmann Generators enable equilibrium sampling from a Boltzmann distribution, defined by an energy function and thermodynamic state. In this work, we introduce Thermodynamic Interpolation (TI), which allows for generating sampling statistics in a temperature-controllable way. We introduce TI flavors that work directly in the ambient configurational space, mapping between different thermodynamic states or through a latent, normally distributed reference state. Our ambient-space approach allows for the specification of arbitrary target temperatures, ensuring generalizability within the temperature range of the training set and demonstrating the potential for extrapolation beyond it. We validate the effectiveness of TI on model systems that exhibit metastability and non-trivial temperature dependencies. Finally, we demonstrate how to combine TI-based sampling to estimate free energy differences through various free energy perturbation methods and provide corresponding approximated kinetic rates estimated through generator extended dynamic mode decomposition (gEDMD). Copyright © 2024, The Authors. All rights reserved.

关键词： Free energy

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On the performance of multidimensional constellation shaping for linear and nonlinear optical fiber channel

On the performance of multidimensional constellation shaping...

引用

49th European Conference on Optical Communications (ECOC 2023)

作者： B. Chen Z. Liang S. Li Y. Lei G. Liga A. Alvarado School of Computer Science and Information Engineering Hefei University of Technology People's Republic of China Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Department of Electrical Engineering Eindhoven University of Technology Netherlands

Multidimensional constellation shaping of up to 32 dimensions with different spectral efficiencies are compared through AWGN and fiber-optic simulations. The results show that no constellation is universal and the balance of required and effective SNRs should be jointly considered for the specific optical transmission scenario.

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A Stable Lithium-ion Battery SOH Estimation Framework for Suppressing Measurement Noise with Unknown Distribution

引用

IEEE Transactions on Transportation Electrification 2025年

作者： Ma, Wentao Xue, Jingsong Li, Yang Guo, Peng Liu, Xinghua Wei, Zhongbao Wang, Yiwen Chen, Badong Xi’an University of Technology School of Electrical Engineering 710048 China Chalmers University of Technology Department of Electrical Engineering Gothenburg41296 Sweden Beijing Institute of Technology National Engineering Laboratory for Electric Vehicles School of Mechanical Engineering Beijing100081 China Hong Kong University of Science and Technology Department of Electronic and Computer Engineering Hong Kong Institute of artificial intelligence and robotics Xi’an Jiaotong University Xi’an710048 China

Existing methods for estimating the state of health (SOH) of lithium-ion battery (LIB) typically rely on the assumption that the distribution of noise (or outliers) in the measurement data is known. However, this assumption rarely holds true for LIB operating under real-word conditions. This article proposes a stable framework for accurate SOH estimation that accommodates noises with unknown distribution in both measurement data and label values. The framework combines generalized correntropy loss (GCL) with Savitzky-Golay (SG) filter and extreme learning machine (ELM) to obtain measurement data filter named SG-GCL and SOH estimator named generalized ELM (GELM), respectively. The SG-GCL filtering of the measurement data keeps the root mean square error (RMSE) within 0.0365%, and Pearson correlation between extracted feature and SOH improves by 0.4963, which in turn leads to the reduction of the RMSE metrics of the ELM for the estimation of the SOH by 43.69%. From the filtering results, feature extraction and estimation results proved its necessity and effectiveness. GELM effectively suppresses the influence of label value noise on the model in the training process, which reduces the SOH estimation RMSE index by more than 0.66%. The results from experiments with different distributional noise conditions show that the proposed SOH estimation framework has excellent and stable performance. © 2015 IEEE.

关键词： Mean square error

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engineering Safety Requirements for Autonomous Driving with Large Language Models

arXiv

引用

arXiv 2024年

作者： Ali, Nouri Beatriz, Cabrero-Daniel Fredrik, Törner Håkan, Sivencrona Christian, Berger Volvo Cars & Chalmers University of Technology Gothenburg Sweden University of Gothenburg Department of Computer Science and Engineering Gothenburg Sweden Volvo Cars Gothenburg Sweden Zenseact Gothenburg Sweden

Changes and updates in the requirement artifacts, which can be frequent in the automotive domain, are a challenge for SafetyOps. Large Language Models (LLMs), with their impressive natural language understanding and generating capabilities, can play a key role in automatically refining and decomposing requirements after each update. In this study, we propose a prototype of a pipeline of prompts and LLMs that receives an item definition and outputs solutions in the form of safety requirements. This pipeline also performs a review of the requirement dataset and identifies redundant or contradictory requirements. We first identified the necessary characteristics for performing HARA and then defined tests to assess an LLM’s capability in meeting these criteria. We used design science with multiple iterations and let experts from different companies evaluate each cycle quantitatively and qualitatively. Finally, the prototype was implemented at a case company and the responsible team evaluated its efficiency. © 2024, CC BY-NC-ND.

关键词： Risk assessment

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On Shaping Gain of Multidimensional Constellation in Linear and Nonlinear Optical Fiber Channel

arXiv

引用

arXiv 2024年

作者： Chen, Bin Liang, Zhiwei Lei, Yi Deng, JingXin Li, Shen Liga, Gabriele School of Computer Science and Information Engineering Hefei University of Technology Hefei China Intelligent Interconnected Systems Laboratory of Anhui Province China Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Department of Electrical and Computer Engineering Université Laval Québec Canada Department of Electrical Engineering Eindhoven University of Technology Eindhoven Netherlands

Utilizing the multi-dimensional (MD) space for constellation shaping has been proven to be an effective approach for achieving shaping gains. Despite there exists a variety of MD modulation formats tailored for specific optical transmission scenarios, there remains a notable absence of a dependable comparison method for efficiently and promptly re-evaluating their performance in arbitrary transmission systems. In this paper, we introduce an analytical nonlinear interference (NLI) power model-based shaping gain estimation method to enable a fast performance evaluation of various MD modulation formats in coherent dual-polarization (DP) optical transmission system. In order to extend the applicability of this method to a broader set of modulation formats, we extend the established NLI model to take the 4D joint distribution into account and thus able to analyze the complex interactions of non-iid signaling in DP systems. With the help of the NLI model, we conduct a comprehensive analysis of the state-of-the-art modulation formats and investigate their actual shaping gains in two types of optical fiber communication scenarios (multi-span and single-span). The numerical simulation shows that for arbitrary modulation formats, the NLI power and relative shaping gains in terms of signal-to-noise ratio can be more accurately estimated by capturing the statistics of MD symbols. Furthermore, the proposed method further validates the effectiveness of the reported NLI-tolerant modulation format in the literature, which reveals that the linear shaping gains and modulation-dependent NLI should be jointly considered for nonlinearity mitigation. © 2024, CC BY-NC-SA.

关键词： Optical fibers

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