311 research outputs found
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
The Fine-Grained Complexity of CFL Reachability
Many problems in static program analysis can be modeled as the context-free
language (CFL) reachability problem on directed labeled graphs. The CFL
reachability problem can be generally solved in time , where is the
number of vertices in the graph, with some specific cases that can be solved
faster. In this work, we ask the following question: given a specific CFL, what
is the exact exponent in the monomial of the running time? In other words, for
which cases do we have linear, quadratic or cubic algorithms, and are there
problems with intermediate runtimes? This question is inspired by recent
efforts to classify classic problems in terms of their exact polynomial
complexity, known as {\em fine-grained complexity}. Although recent efforts
have shown some conditional lower bounds (mostly for the class of combinatorial
algorithms), a general picture of the fine-grained complexity landscape for CFL
reachability is missing.
Our main contribution is lower bound results that pinpoint the exact running
time of several classes of CFLs or specific CFLs under widely believed lower
bound conjectures (Boolean Matrix Multiplication and -Clique). We
particularly focus on the family of Dyck- languages (which are strings with
well-matched parentheses), a fundamental class of CFL reachability problems. We
present new lower bounds for the case of sparse input graphs where the number
of edges is the input parameter, a common setting in the database
literature. For this setting, we show a cubic lower bound for Andersen's
Pointer Analysis which significantly strengthens prior known results.Comment: Appeared in POPL 2023. Please note the erratum on the first pag
Jornadas Nacionales de Investigación en Ciberseguridad: actas de las VIII Jornadas Nacionales de Investigación en ciberseguridad: Vigo, 21 a 23 de junio de 2023
Jornadas Nacionales de Investigación en Ciberseguridad (8ª. 2023. Vigo)atlanTTicAMTEGA: Axencia para a modernización tecnolóxica de GaliciaINCIBE: Instituto Nacional de Cibersegurida
A review of commercialisation mechanisms for carbon dioxide removal
The deployment of carbon dioxide removal (CDR) needs to be scaled up to achieve net zero emission pledges. In this paper we survey the policy mechanisms currently in place globally to incentivise CDR, together with an estimate of what different mechanisms are paying per tonne of CDR, and how those costs are currently distributed. Incentive structures are grouped into three structures, market-based, public procurement, and fiscal mechanisms. We find the majority of mechanisms currently in operation are underresourced and pay too little to enable a portfolio of CDR that could support achievement of net zero. The majority of mechanisms are concentrated in market-based and fiscal structures, specifically carbon markets and subsidies. While not primarily motivated by CDR, mechanisms tend to support established afforestation and soil carbon sequestration methods. Mechanisms for geological CDR remain largely underdeveloped relative to the requirements of modelled net zero scenarios. Commercialisation pathways for CDR require suitable policies and markets throughout the projects development cycle. Discussion and investment in CDR has tended to focus on technology development. Our findings suggest that an equal or greater emphasis on policy innovation may be required if future requirements for CDR are to be met. This study can further support research and policy on the identification of incentive gaps and realistic potential for CDR globally
Energy Data Analytics for Smart Meter Data
The principal advantage of smart electricity meters is their ability to transfer digitized electricity consumption data to remote processing systems. The data collected by these devices make the realization of many novel use cases possible, providing benefits to electricity providers and customers alike. This book includes 14 research articles that explore and exploit the information content of smart meter data, and provides insights into the realization of new digital solutions and services that support the transition towards a sustainable energy system. This volume has been edited by Andreas Reinhardt, head of the Energy Informatics research group at Technische Universität Clausthal, Germany, and Lucas Pereira, research fellow at Técnico Lisboa, Portugal
A high-performance open-source framework for multiphysics simulation and adjoint-based shape and topology optimization
The first part of this thesis presents the advances made in the Open-Source software SU2,
towards transforming it into a high-performance framework for design and optimization of
multiphysics problems. Through this work, and in collaboration with other authors, a tenfold
performance improvement was achieved for some problems. More importantly, problems that
had previously been impossible to solve in SU2, can now be used in numerical optimization
with shape or topology variables. Furthermore, it is now exponentially simpler to study new
multiphysics applications, and to develop new numerical schemes taking advantage of modern
high-performance-computing systems.
In the second part of this thesis, these capabilities allowed the application of topology optimiza-
tion to medium scale fluid-structure interaction problems, using high-fidelity models (nonlinear
elasticity and Reynolds-averaged Navier-Stokes equations), which had not been done before
in the literature. This showed that topology optimization can be used to target aerodynamic
objectives, by tailoring the interaction between fluid and structure. However, it also made ev-
ident the limitations of density-based methods for this type of problem, in particular, reliably
converging to discrete solutions. This was overcome with new strategies to both guarantee and
accelerate (i.e. reduce the overall computational cost) the convergence to discrete solutions in
fluid-structure interaction problems.Open Acces
1979 February, Memphis State University bulletin
Vol. 68, No. 1 of the Memphis State University bulletin containing the undergraduate catalog for 1979-1980, 1979 February.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1148/thumbnail.jp
Proceedings of the 11th International Conference on Kinanthropology
The 11th International Conference on Kinantropology was held on the Nov 29 – Dec 1, 2017 in Brno and was organized by the Faculty of Sports Studies, Masaryk University and the Faculty of Kinesiology, University of Zagreb. This year was divided into several themes: sports medicine, sport and social science, sport training, healthy lifestyle and healthy ageing, sports management, analysis of human movement. Part of the conference was also a symposium Atletika and Ortoreha that gathered specialists in physiotherapy
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