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Vertices of Degree k in random Unlabeled Trees

Electronic Notes in Discrete Mathematics 2009年 34卷 41-45页

作者： Panagiotou, Konstantinos Sinha, Makrand Department of Algorithms and Complexity Max-Planck-Institute for Informatics 66123 Saarbrücken Germany Department of Computer Science and Engineering Indian Institute of Technology Kanpur 208016 Kanpur India

Let Hn be the class of vertex-rooted unlabeled trees with n vertices, and denote by Hn a tree that is drawn uniformly at random from this set. In this work we study the number degk (Hn) of vertices of degree k in Hn. ... 详细信息

Let H_n be the class of vertex-rooted unlabeled trees with n vertices, and denote by H_n a tree that is drawn uniformly at random from this set. In this work we study the number deg_k (H_n) of vertices of degree k in H_n. In particular, for k = O ((frac(log n, log log n))^{1 / 2}) we show exponential-type bounds for the probability that deg_k (H_n) deviates from its expectation. On the technical side, our proofs are based on the analysis of a randomized algorithm that generates unlabeled trees in the so-called Boltzmann model. The analysis of such algorithms is quite well-understood for classes of labeled graphs. Comparable algorithms for unlabeled classes are unfortunately much more complex. We demonstrate in this work that they can be analyzed very precisely for classes of unlabeled graphs as well. © 2009 Elsevier B.V. All rights reserved.

关键词： Boltzmann Sampling Degree Sequence random Unlabeled Trees

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Search for Diphoton Events with Large Missing Transverse Energy in 7 TeV Proton-Proton Collisions with the ATLAS Detector

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Physical Review Letters 2011年第12期106卷 121803-121803页

作者： G. Aad B. Abbott J. Abdallah A. A. Abdelalim A. Abdesselam O. Abdinov B. Abi M. Abolins H. Abramowicz H. Abreu E. Acerbi B. S. Acharya M. Ackers D. L. Adams T. N. Addy J. Adelman M. Aderholz S. Adomeit P. Adragna T. Adye S. Aefsky J. A. Aguilar-Saavedra M. Aharrouche S. P. Ahlen F. Ahles A. Ahmad M. Ahsan G. Aielli T. Akdogan T. P. A. Åkesson G. Akimoto A. V. Akimov M. S. Alam M. A. Alam S. Albrand M. Aleksa I. N. Aleksandrov M. Aleppo F. Alessandria C. Alexa G. Alexander G. Alexandre T. Alexopoulos M. Alhroob M. Aliev G. Alimonti J. Alison M. Aliyev P. P. Allport S. E. Allwood-Spiers J. Almond A. Aloisio R. Alon A. Alonso J. Alonso M. G. Alviggi K. Amako P. Amaral C. Amelung V. V. Ammosov A. Amorim G. Amorós N. Amram C. Anastopoulos T. Andeen C. F. Anders K. J. Anderson A. Andreazza V. Andrei M-L. Andrieux X. S. Anduaga A. Angerami F. Anghinolfi N. Anjos A. Annovi A. Antonaki M. Antonelli S. Antonelli J. Antos F. Anulli S. Aoun L. Aperio Bella R. Apolle G. Arabidze I. Aracena Y. Arai A. T. H. Arce J. P. Archambault S. Arfaoui J-F. Arguin E. Arik M. Arik A. J. Armbruster K. E. Arms S. R. Armstrong O. Arnaez C. Arnault A. Artamonov G. Artoni D. Arutinov S. Asai R. Asfandiyarov S. Ask B. Åsman L. Asquith K. Assamagan A. Astbury A. Astvatsatourov G. Atoian B. Aubert B. Auerbach E. Auge K. Augsten M. Aurousseau N. Austin R. Avramidou D. Axen C. Ay G. Azuelos Y. Azuma M. A. Baak G. Baccaglioni C. Bacci A. M. Bach H. Bachacou K. Bachas G. Bachy M. Backes E. Badescu P. Bagnaia S. Bahinipati Y. Bai D. C. Bailey T. Bain J. T. Baines O. K. Baker S. Baker F. Baltasar Dos Santos Pedrosa E. Banas P. Banerjee Sw. Banerjee D. Banfi A. Bangert V. Bansal H. S. Bansil L. Barak S. P. Baranov A. Barashkou A. Barbaro Galtieri T. Barber E. L. Barberio D. Barberis M. Barbero D. Y. Bardin T. Barillari M. Barisonzi T. Barklow N. Barlow B. M. Barnett R. M. Barnett A. Baroncelli A. J. Barr F. Barreiro J. Barreiro Guimarães da Costa P. Barrillon R. Bartoldus A. E. Barton D. Bartsch R. L. Bates L. Batkova J. R. Batley A. Battaglia M. Battist Albert-Ludwigs-Universität Fakultät für Mathematik und Physik Hermann-Herder Str. 3 D - 79104 Freiburg i.Br. Germany University of Oklahoma Homer L. Dodge Department of Physics and Astronomy 440 West Brooks Room 100 Norman Oklahoma 73019-0225 USA Institut de Física d’Altes Energies IFAE Edifici Cn Universitat Autònoma de Barcelona ES - 08193 Bellaterra (Barcelona) Spain Université de Genève Section de Physique 24 rue Ernest Ansermet CH - 1211 Geneve 4 Switzerland Oxford University Department of Physics Denys Wilkinson Building Keble Road Oxford OX1 3RH United Kingdom Institute of Physics Azerbaijan Academy of Sciences H. Javid Avenue 33 AZ 143 Baku Azerbaijan Oklahoma State University Department of Physics 145 Physical Sciences Building Stillwater Oklahoma 74078-3072 USA Michigan State University Department of Physics and Astronomy High Energy Physics Group East Lansing Michigan 48824-2320 USA Tel Aviv University Raymond and Beverly Sackler School of Physics and Astronomy Ramat Aviv IL - Tel Aviv 69978 Israel LAL Université Paris-Sud IN2P3/CNRS Orsay France INFN Sezione di Milano Milano Italy Università di Milano Dipartimento di Fisica via Celoria 16 IT - 20133 Milano Italy INFN Gruppo Collegato di Udine Udine Italy ICTP Strada Costiera 11 IT-34014 Trieste Italy University of Bonn Physikalisches Institut Nussallee 12 D - 53115 Bonn Germany Brookhaven National Laboratory Physics Department Building 510A Upton New York 11973 USA Hampton University Department of Physics Hampton Virginia 23668 USA Yale University Department of Physics PO Box 208121 New Haven Connecticut 06520-8121 USA Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6 80805 München Germany Ludwig-Maximilians-Universität München Fakultät für Physik Am Coulombwall 1 DE - 85748 Garching Germany Queen Mary University of London Department of Physics Mile End Road London E1 4NS United Kingdom Rutherford Appleton Laboratory Science and Technolo

A search for diphoton events with large missing transverse energy is presented. The data were collected with the ATLAS detector in proton-proton collisions at s=7 TeV at the CERN Large Hadron Collider and correspond to an integrated luminosity of 3.1 pb−1. No excess of such events is observed above the standard model background prediction. In the context of a specific model with one universal extra dimension with compactification radius R and gravity-induced decays, values of 1/R<729 GeV are excluded at 95% C. L., providing the most sensitive limit on this model to date.

关键词： Tellurium compounds

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On assessing robustness in transportation planning

On assessing robustness in transportation planning

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9th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems, ATMOS 2009

作者： Bessas, Apostolus Zaroliagis, Christos R.A. Computer Technology Institute Patras University Campus N. Kazantzaki Str. 26504 Patras Greece Department of Computer Engineering and Informatics University of Patras 26500 Patras Greece

ISBN: (纸本)9783939897118

We consider a fundamental problem, called QoS-aware Multicommodity Flow, for assessing robustness in transportation planning. It constitutes a natural generalization of the weighted multicommodity flow problem, where the demands and commodity values are elastic to the Quality-of-Service (QoS) characteristics of the underlying network. The problem is also fundamental in other domains beyond transportation planning. In this work, we provide an extensive experimental study of two FPTAS for the QoS-aware Multicommodity Flow Problem enhanced with several heuristics, and show the superiority of a new heuristic we introduce here.

关键词： Operations research

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Incentive-compatible robust line planning

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作者： Bessas, Apostolos Kontogiannis, Spyros Zaroliagis, Christos R.A. Computer Technology Institute Patras University Campus N. Kazantzaki Str. Patras 26500 Greece Computer Science Department University of Ioannina Ioannina 45110 Greece Department of Computer Engineering and Informatics University of Patras Patras 26500 Greece

ISBN: (纸本)3642054641

The problem of robust line planning requests for a set of origin-destination paths (lines) along with their frequencies in an underlying railway network infrastructure, which are robust to fluctuations of real-time parameters of the solution. In this work, we investigate a variant of robust line planning stemming from recent regulations in the railway sector that introduce competition and free railway markets, and set up a new application scenario: There is a (potentially large) number of line operators that have their lines fixed and operate as competing entities issuing frequency requests, while the management of the infrastructure itself remains the responsibility of a single entity, the network operator. The line operators are typically unwilling to reveal their true incentives, while the network operator strives to ensure a fair (or socially optimal) usage of the infrastructure, e.g., by maximizing the (unknown to him) aggregate incentives of the line operators. By investigating a resource allocation mechanism (originally developed in the context of communication networks), we show that a socially optimal solution can be accomplished in certain situations via an anonymous incentive-compatible pricing scheme for the usage of the shared resources that is robust against the unknown incentives and the changes in the demands of the *** brings up a new notion of robustness, which we call incentive-compatible robustness, that considers as robustness of the system its tolerance to the entities' unknown incentives and elasticity of demands, aiming at an eventual stabilization to an equilibrium point that is as close as possible to the social optimum. © 2009 Springer-Verlag Berlin Heidelberg.

关键词： Planning

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Applying fuzzy DLs in the extraction of image semantics

Applying fuzzy DLs in the extraction of image semantics

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作者： Dasiopoulou, Stamatia Kompatsiaris, Ioannis Strintzis, Michael G. Centre for Research and Technology Hellas Informatics and Telematics Institute Thessaloniki Greece Information Processing Laboratory Electrical and Computer Engineering Department Aristotle University of Thessaloniki Greece

ISBN: (纸本)3642105610

Statistical learning approaches, bounded mainly to knowledge related to perceptual manifestations of semantics, fall short to adequately utilise the meaning and logical connotations pertaining to the extracted image semantics. Instigated by the Semantic Web, ontologies have appealed to a significant share of synergistic approaches towards the combined use of statistical learning and explicit semantics. While the relevant literature tends to disregard the uncertainty involved, and treats the extracted image descriptions as coherent, two valued propositions, this paper explores reasoning under uncertainty towards a more accurate and pragmatic handling of the underlying semantics. Using fuzzy DLs, the proposed reasoning framework captures the vagueness of the extracted image descriptions and accomplishes their semantic interpretation, while resolving inconsistencies rising from contradictory descriptions. To evaluate the proposed reasoning framework, an experimental implementation using the fuzzyDL Description Logic reasoner has been carried out. Experiments in the domain of outdoor images illustrate the added value, while outlining challenges to be further addressed. © 2009 Springer-Verlag.

关键词： Data description

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A preemptive scheduling scheme for flexible QoS provisioning in OBS networks

A preemptive scheduling scheme for flexible QoS provisioning...

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2009 6th International Conference on Broadband Communications, Networks and Systems, BROADNETS 2009

作者： ramantas, Kostas Vargas, Tito raúl Guerri, Juan Carlos Vlachos, Kyriakos Computer Engineering and Informatics Department Research Academic Computer Technology Institute University of Patras Rio Greece ITEAM Instituto de Telecomunicaciones Y Aplicaciones Multimedia Universidad Politécnica de Valencia Valencia Spain

ISBN: (纸本)9789639799493

In Optical Burst Switching (OBS) networks one of the most challenging problems is to provide service differentiation. The lack of buffering in the intermediate nodes, makes QoS provisioning in OBS networks a difficult problem to address. In this work, we propose a scheduling algorithm that supports QoS based on preemptions, which are controlled by a novel preemption policy. Our claims are validated by analytical modelling and experimental analysis through simulations using data belonging to two different classes of service - best effort and video streaming data. Performance evaluation is based on throughput measurements for best effort class, and perceived quality metrics like PSNR and MOS scores for the video streaming class.

关键词： Quality of service

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Study of jet shapes in inclusive jet production in pp collisions at s=7 TeV using the ATLAS detector

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Physical Review D 2011年第5期83卷 052003-052003页

作者： G. Aad B. Abbott J. Abdallah A. A. Abdelalim A. Abdesselam O. Abdinov B. Abi M. Abolins H. Abramowicz H. Abreu E. Acerbi B. S. Acharya M. Ackers D. L. Adams T. N. Addy J. Adelman M. Aderholz S. Adomeit P. Adragna T. Adye S. Aefsky J. A. Aguilar-Saavedra M. Aharrouche S. P. Ahlen F. Ahles A. Ahmad M. Ahsan G. Aielli T. Akdogan T. P. A. Åkesson G. Akimoto A. V. Akimov M. S. Alam M. A. Alam S. Albrand M. Aleksa I. N. Aleksandrov M. Aleppo F. Alessandria C. Alexa G. Alexander G. Alexandre T. Alexopoulos M. Alhroob M. Aliev G. Alimonti J. Alison M. Aliyev P. P. Allport S. E. Allwood-Spiers J. Almond A. Aloisio R. Alon A. Alonso J. Alonso M. G. Alviggi K. Amako P. Amaral C. Amelung V. V. Ammosov A. Amorim G. Amorós N. Amram C. Anastopoulos T. Andeen C. F. Anders K. J. Anderson A. Andreazza V. Andrei M-L. Andrieux X. S. Anduaga A. Angerami F. Anghinolfi N. Anjos A. Annovi A. Antonaki M. Antonelli S. Antonelli J. Antos F. Anulli S. Aoun L. Aperio Bella R. Apolle G. Arabidze I. Aracena Y. Arai A. T. H. Arce J. P. Archambault S. Arfaoui J-F. Arguin E. Arik M. Arik A. J. Armbruster K. E. Arms S. R. Armstrong O. Arnaez C. Arnault A. Artamonov G. Artoni D. Arutinov S. Asai R. Asfandiyarov S. Ask B. Åsman L. Asquith K. Assamagan A. Astbury A. Astvatsatourov G. Atoian B. Aubert B. Auerbach E. Auge K. Augsten M. Aurousseau N. Austin R. Avramidou D. Axen C. Ay G. Azuelos Y. Azuma M. A. Baak G. Baccaglioni C. Bacci A. M. Bach H. Bachacou K. Bachas G. Bachy M. Backes E. Badescu P. Bagnaia S. Bahinipati Y. Bai D. C. Bailey T. Bain J. T. Baines O. K. Baker S. Baker F. Baltasar Dos Santos Pedrosa E. Banas P. Banerjee Sw. Banerjee D. Banfi A. Bangert V. Bansal H. S. Bansil L. Barak S. P. Baranov A. Barashkou A. Barbaro Galtieri T. Barber E. L. Barberio D. Barberis M. Barbero D. Y. Bardin T. Barillari M. Barisonzi T. Barklow N. Barlow B. M. Barnett R. M. Barnett A. Baroncelli A. J. Barr F. Barreiro J. Barreiro Guimarães da Costa P. Barrillon R. Bartoldus A. E. Barton D. Bartsch R. L. Bates L. Batkova J. R. Batley A. Battaglia M. Battist Albert-Ludwigs-Universität Fakultät für Mathematik und Physik Hermann-Herder Str. 3 D - 79104 Freiburg i.Br. Germany University of Oklahoma Homer L. Dodge Department of Physics and Astronomy 440 West Brooks Room 100 Norman Oklahoma 73019-0225 USA Institut de Física d’Altes Energies IFAE Edifici Cn Universitat Autònoma de Barcelona ES - 08193 Bellaterra (Barcelona) Spain Université de Genève Section de Physique 24 rue Ernest Ansermet CH - 1211 Geneve 4 Switzerland Oxford University Department of Physics Denys Wilkinson Building Keble Road Oxford OX1 3RH United Kingdom Institute of Physics Azerbaijan Academy of Sciences H. Javid Avenue 33 AZ 143 Baku Azerbaijan Oklahoma State University Department of Physics 145 Physical Sciences Building Stillwater Oklahoma 74078-3072 USA Michigan State University Department of Physics and Astronomy High Energy Physics Group East Lansing Michigan 48824-2320 USA Tel Aviv University Raymond and Beverly Sackler School of Physics and Astronomy Ramat Aviv IL - Tel Aviv 69978 Israel LAL Université Paris-Sud IN2P3/CNRS Orsay France INFN Sezione di Milano via Celoria 16 IT - 20133 Milano Italy Università di Milano Dipartimento di Fisica via Celoria 16 IT - 20133 Milano Italy INFN Gruppo Collegato di Udine Strada Costiera 11 IT-34014 Trieste Italy ICTP Strada Costiera 11 IT-34014 Trieste Italy University of Bonn Physikalisches Institut Nussallee 12 D - 53115 Bonn Germany Brookhaven National Laboratory Physics Department Building 510A Upton New York 11973 USA Hampton University Department of Physics Hampton Virginia 23668 USA Yale University Department of Physics P.O. Box 208121 New Haven Connecticut 06520-8121 USA Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6 80805 München Germany Ludwig-Maximilians-Universität München Fakultät für Physik Am Coulombwall 1 DE - 85748 Garching Germany Queen Mary University of London Department of Physics Mile End Road London E1 4NS United

Jet shapes have been measured in inclusive jet production in proton-proton collisions at s=7 TeV using 3 pb−1 of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeVrapidity in the region |y|<2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and nonperturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.

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Least-squares polynomial approximation for short-term generation unit asset valuation

Least-squares polynomial approximation for short-term genera...

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2009 IEEE/PES Power Systems Conference and Exposition, PSCE 2009

作者： Sisworahardjo, N.S. El-Keib, A.A. Alam, M.S. School of Electrical Engineering and Informatics Bandung Institute of Technology Bandung 40132 Indonesia Department of Electrical and Computer Engineering University of South Alabama Mobile AL 36688 United States Department of Electrical Engineering Petroleum Institute United Arab Emirates

ISBN: (纸本)9781424438112

In short-term generation unit asset valuation, a decision whether to turn the unit "on" or "off" is relied upon the present realization of electricity and fuel prices. When the electricity and fuel prices are on an indifference locus (IL), the decision made will not effecting the expected profit. Therefore, the identification of ILs is crucial step in unit asset valuation method. A novel least-squares polynomial-based technique to approximate the continuous path of ILs is developed and implemented. By using this technique, the unit asset valuation problem can be solved faster than the standard method without compromising its accuracy. Testing and model verification are performed on actual data of the PJM power market. The results indicate that the proposed technique is effective and efficient while producing significantly accurate results. It reduces the computational burden by more than 245 times and 0.90% error for 2000 simulation times. ©2009 IEEE.

关键词： Polynomial approximation

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Measurement of underlying event characteristics using charged particles in pp collisions at s=900 GeV and 7 TeV with the ATLAS detector

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Physical Review D 2011年第11期83卷 112001-112001页

作者： G. Aad B. Abbott J. Abdallah A. A. Abdelalim A. Abdesselam O. Abdinov B. Abi M. Abolins H. Abramowicz H. Abreu E. Acerbi B. S. Acharya M. Ackers D. L. Adams T. N. Addy J. Adelman M. Aderholz S. Adomeit P. Adragna T. Adye S. Aefsky J. A. Aguilar-Saavedra M. Aharrouche S. P. Ahlen F. Ahles A. Ahmad H. Ahmed M. Ahsan G. Aielli T. Akdogan T. P. A. Åkesson G. Akimoto A. V. Akimov M. S. Alam M. A. Alam S. Albrand M. Aleksa I. N. Aleksandrov M. Aleppo F. Alessandria C. Alexa G. Alexander G. Alexandre T. Alexopoulos M. Alhroob M. Aliev G. Alimonti J. Alison M. Aliyev P. P. Allport S. E. Allwood-Spiers J. Almond A. Aloisio R. Alon A. Alonso J. Alonso M. G. Alviggi K. Amako P. Amaral C. Amelung V. V. Ammosov A. Amorim G. Amorós N. Amram C. Anastopoulos T. Andeen C. F. Anders K. J. Anderson A. Andreazza V. Andrei M-L. Andrieux X. S. Anduaga A. Angerami F. Anghinolfi N. Anjos A. Annovi A. Antonaki M. Antonelli S. Antonelli J. Antos B. Antunovic F. Anulli S. Aoun R. Apolle G. Arabidze I. Aracena Y. Arai A. T. H. Arce J. P. Archambault S. Arfaoui J-F. Arguin T. Argyropoulos E. Arik M. Arik A. J. Armbruster K. E. Arms S. R. Armstrong O. Arnaez C. Arnault A. Artamonov D. Arutinov S. Asai R. Asfandiyarov S. Ask B. Åsman L. Asquith K. Assamagan A. Astbury A. Astvatsatourov G. Atoian B. Aubert B. Auerbach E. Auge K. Augsten M. Aurousseau N. Austin R. Avramidou D. Axen C. Ay G. Azuelos Y. Azuma M. A. Baak G. Baccaglioni C. Bacci A. M. Bach H. Bachacou K. Bachas G. Bachy M. Backes E. Badescu P. Bagnaia Y. Bai D. C. Bailey T. Bain J. T. Baines O. K. Baker S. Baker F. Baltasar Dos Santos Pedrosa E. Banas P. Banerjee Sw. Banerjee D. Banfi A. Bangert V. Bansal H. S. Bansil L. Barak S. P. Baranov A. Barashkou A. Barbaro Galtieri T. Barber E. L. Barberio D. Barberis M. Barbero D. Y. Bardin T. Barillari M. Barisonzi T. Barklow N. Barlow B. M. Barnett R. M. Barnett A. Baroncelli A. J. Barr F. Barreiro J. Barreiro Guimarães da Costa P. Barrillon R. Bartoldus A. E. Barton D. Bartsch R. L. Bates L. Batkova J. R. Batley A. Battaglia M. Battistin Albert-Ludwigs-Universität Fakultät für Mathematik und Physik Hermann-Herder Strasse 3 D - 79104 Freiburg i.Br. Germany University of Oklahoma Homer L. Dodge Department of Physics and Astronomy 440 West Brooks Room 100 Norman Oklahoma 73019-0225 USA Institut de Física d’Altes Energies IFAE Edifici Cn Universitat Autònoma de Barcelona ES - 08193 Bellaterra (Barcelona) Spain Université de Genève Section de Physique 24 rue Ernest Ansermet CH - 1211 Geneve 4 Switzerland Oxford University Department of Physics Denys Wilkinson Building Keble Road Oxford OX1 3RH United Kingdom Institute of Physics Azerbaijan Academy of Sciences H. Javid Avenue 33 AZ 143 Baku Azerbaijan Oklahoma State University Department of Physics 145 Physical Sciences Building Stillwater Oklahoma 74078-3072 USA Michigan State University Department of Physics and Astronomy High Energy Physics Group East Lansing Michigan 48824-2320 USA Tel Aviv University Raymond and Beverly Sackler School of Physics and Astronomy Ramat Aviv IL - Tel Aviv 69978 Israel LAL Université du Paris-Sud IN2P3/CNRS Orsay France INFN Sezione di Milano Italy Università di Milano Dipartimento di Fisica via Celoria 16 IT - 20133 Milano Italy INFN Gruppo Collegato di Udine Italy ICTP Strada Costiera 11 IT-34014 Trieste Italy University of Bonn Physikalisches Institut Nussallee 12 D - 53115 Bonn Germany Brookhaven National Laboratory Physics Department Building 510A Upton New York 11973 USA Hampton University Department of Physics Hampton Virginia 23668 USA Yale University Department of Physics P.O. Box 208121 New Haven Connecticut 06520-8121 USA Max-Planck-Institut für Physik (Werner-Heisenberg-Institut) Föhringer Ring 6 80805 München Germany Ludwig-Maximilians-Universität München Fakultät für Physik Am Coulombwall 1 DE - 85748 Garching Germany Queen Mary University of London Department of Physics Mile End Road London E1 4NS United Kingdom Rutherford Appleton Laboratory Science and Technology Facili

Measurements of charged particle distributions, sensitive to the underlying event, have been performed with the ATLAS detector at the LHC. The measurements are based on data collected using a minimum-bias trigger to select proton-proton collisions at center-of-mass energies of 900 GeV and 7 TeV. The “underlying event” is defined as those aspects of a hadronic interaction attributed not to the hard scattering process, but rather to the accompanying interactions of the rest of the proton. Three regions are defined in azimuthal angle with respect to the highest transverse momentum charged particle in the event, such that the region transverse to the dominant momentum-flow is most sensitive to the underlying event. In each of these regions, distributions of the charged particle multiplicity, transverse momentum density, and average pT are measured. The data show generally higher underlying event activity than that predicted by Monte Carlo models tuned to pre-LHC data.

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Efficient Coordination Mechanisms for Unrelated Machine Scheduling 09

Efficient Coordination Mechanisms for Unrelated Machine Sche...

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Annual ACM-Society for Industrial and Applied Mathmatics Symposium on Discrete Algorithms

作者： Ioannis Caragiannis Research Academic Computer Technology Institute & Department of Computer Engineering and Informatics University of Patras

We present three new coordination mechanisms for scheduling n selfish jobs on m unrelated machines. A coordination mechanism aims to mitigate the impact of selfishness of jobs on the efficiency of schedules by defining a local scheduling policy on each machine. The scheduling policies induce a game among the jobs and each job prefers to be scheduled on a machine so that its completion time is minimum given the assignments of the other jobs. We consider the maximum completion time among all jobs as the measure of the efficiency of schedules. The approximation ratio of a coordination mechanism quantifies the efficiency of pure Nash equilibria (price of anarchy) of the induced game. Our mechanisms are deterministic, local, and preemptive in the sense that the scheduling policy does not necessarily process the jobs in an uninterrupted way and may introduce some idle time. Our first coordination mechanism has approximation ratio O(logm) and always guarantees that the induced game has pure Nash equilibria to which the system con- verges in at most n rounds. This result improves a recent bound of O(log^2 m) due to Azar, Jain, and Mirrokni and, similarly to their mechanism, our mechanism uses a global ordering of the jobs according to their distinct IDs. Next we study the intriguing scenario where jobs are anonymous, i.e., they have no IDs. In this case, coordination mechanisms can only distinguish between jobs that have different load characteristics. Our second mechanism handles anonymous jobs and has approximation ratio O (logm/log logm) although the game induced is not a potential game and, hence, the existence of pure Nash equilibria is not guaranteed by potential function arguments. However, it provides evidence that the known lower bounds for non-preemptive coordination mechanisms could be beaten using preemptive scheduling policies. Our third coordination mechanism also handles anonymous jobs and has a nice "cost-revealing" potential function. Besides in proving the

关键词： jobs Game theory Game animals machine scheduling potential function Hunting Completion time Anarchy scheduling policy Nash equilibrium

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