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Approximation and competitive algorithms for single-minded selling problem 1

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12th International Conference on Algorithmic Aspects in Information and Management, AAIM 2018

作者： Chin, Francis Y. L. Poon, Sheung-Hung Ting, Hing-Fung Xu, Dachuan Yu, Dongxiao Zhang, Yong Department of Computer Science The University of Hong Kong Pok Fu Lam Hong Kong School of Computer Science University of Nottingham Ningbo China Ningbo China Beijing Institute for Scientific and Engineering Computing Beijing University of Technology Beijing China Institute of Intelligent Computing School of Computer Science and Technology Shandong University Qingdao266237 China Research Center for High Performance Computing Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China

ISBN: (数字)9783030046187

ISBN: (纸本)9783030046170

The problem of item selling with the objective of maximizing the revenue is studied. Given a seller with k types of items and n single-minded buyers, i.e., each buyer is only interested in a particular bundle of items, to maximize the revenue, the seller must carefully assign some amount of bundles to each buyer with respect to the buyer’s accepted price. Each buyer bi is associated with a value function vi(·) such that vi(x) is the accepted unit bundle price bi is willing to pay for x bundles. We show that the single-minded item selling problem is NP-hard. Moreover, we give an O(√k)-approximation algorithm. For the online version, i.e., the buyers come one by one and the decision on each buyer must be made before the arrival of the next buyer, an O(√k · (log h + log k))- competitive algorithm is achieved, where h is the highest unit item price among all buyers. © Springer Nature Switzerland AG 2018.

关键词： Sales

Simulating nearby disc galaxies on the main star formation sequence I. Bar formation and the building of the central gas reservoir

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arXiv 2024年

作者： Verwilghen, Pierrick Emsellem, Eric Renaud, Florent Valentini, Milena Sun, Jiayi Jeffreson, Sarah Klessen, Ralf S. Sormani, Mattia C. Barnes, Ashley T. Dolag, Klaus Grasha, Kathryn Liang, Fu-Heng Meidt, Sharon Neumann, Justus Querejeta, Miguel Schinnerer, Eva Williams, Thomas G. Excellence Cluster ORIGINS Boltzmannstraße 2 Garching85748 Germany European Southern Observatory Karl-Schwarzschild-Straße 2 Garching85748 Germany Univ Lyon Univ Lyon1 ENS de Lyon CNRS Centre de Recherche Astrophysique de Lyon UMR5574 Saint-Genis-LavalF-69230 France Observatoire Astronomique de Strasbourg Université de Strasbourg CNRS UMR 7550 StrasbourgF-67000 France University of Strasbourg Institute for Advanced Study 5 allée du Général Rouvillois StrasbourgF-67083 France Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 TriesteI-34131 Italy INAF – Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy Department of Astrophysical Sciences Princeton University 4 Ivy Lane PrincetonNJ08544 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA United States Universität Heidelberg Zentrum für Astronomie Institut für Theoretische Astrophysik Albert-Ueberle-Str. 2 HeidelbergD-69120 Germany Universität Heidelberg Interdisziplinäres Zentrum für Wissenschaftliches Rechnen Im Neuenheimer Feld 205 HeidelbergD-69120 Germany Università dell’Insubria via Valleggio 11 Como22100 Italy Department of Physics University of Surrey GuildfordGU2 7XH United Kingdom Universitäts-Sternwarte Fakultät für Physik Ludwig-Maximilians-Universität München Scheinerstr. 1 München81679 Germany Max-Planck-Institut für Astrophysik Karl-Schwarzschild-Straße 1 Garching85741 Germany Research School of Astronomy and Astrophysics Australian National University CanberraACT2611 Australia Australia Sub-Department of Astrophysics Department of Physics University of Oxford Keble Road OxfordOX1 3RH United Kingdom Sterrenkundig Observatorium Universiteit Gent Krijgslaan 281 S9 GentB-9000 Belgium Max Planck Institut für Astronomie Königstuhl 17 Heidelberg69117 Germany C/Alfonso XII 3 Madri

Past studies have long emphasised the key role played by galactic stellar bars in the context of disc secular evolution, via the redistribution of gas and stars, the triggering of star formation, and the formation of prominent structures such as rings and central mass concentrations. However, the exact physical processes acting on those structures, as well as the timescales associated with the building and consumption of central gas reservoirs are still not well understood. We are building a suite of hydro-dynamical RAMSES simulations of isolated, low-redshift galaxies that mimic the properties of the PHANGS sample. The initial conditions of the models reproduce the observed stellar mass, disc scale length, or gas fraction, and this paper presents a first subset of these models. Most of our simulated galaxies develop a prominent bar structure, which itself triggers central gas fuelling and the building of an over-density with a typical scale of 100-1000 pc. We confirm that if the host galaxy features an ellipsoidal component, the formation of the bar and gas fuelling are delayed. We show that most of our simulations follow a common time evolution, when accounting for mass scaling and the bar formation time. In our simulations, the stellar mass of 1010 M☉ seems to mark a change in the phases describing the time evolution of the bar and its impact on the interstellar medium. In massive discs (M★ ≥ 1010 M☉), we observe the formation of a central gas reservoir with star formation mostly occurring within a restricted starburst region, leading to a gas depletion phase. Lower-mass systems (M★ 10 M☉) do not exhibit such a depletion phase, and show a more homogeneous spread of star-forming regions along the bar structure, and do not appear to host inner bar-driven discs or rings. Our results seem to be supported by observations, and we briefly discuss how this new suite of simulations can help our understanding of the secular evolution of main sequence disc galaxies. © 2024,

关键词： Gases

A persistent excess of galaxy-galaxy strong lensing observed in galaxy clusters

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arXiv 2023年

作者： Meneghetti, Massimo Cui, Weiguang Rasia, Elena Yepes, Gustavo Acebron, Ana Angora, Giuseppe Bergamini, Pietro Borgani, Stefano Calura, Francesco Despali, Giulia Giocoli, Carlo Granata, Giovanni Grillo, Claudio Knebe, Alexander Macciò, Andrea V. Mercurio, Amata Moscardini, Lauro Natarajan, Priyamvada Ragagnin, Antonio Rosati, Piero Vanzella, Eros INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Piero Gobetti 93/3 BolognaI-40129 Italy INFN-Sezione di Bologna Viale Berti Pichat 6/2 BolognaI-40127 Italy Departamento de Física Teórica Facultad de Ciencias Universidad Autónoma de Madrid Módulo 8 MadridE-28049 Spain Facultad de Ciencias Universidad Autónoma de Madrid MadridE-28049 Spain Institute for Astronomy University of Edinburgh Royal Observatory EdinburghEH9 3HJ United Kingdom INAF – Osservatorio Astronomico di Trieste via Tiepolo 11 TriesteI-34131 Italy IFPU Institute for Fundamental Physics of the Universe via Beirut 2 Trieste34151 Italy INFN Istituto Nazionale di Fisica Nucleare Via Valerio 2 TriesteI-34127 Italy Dipartimento di Fisica Università degli Studi di Milano Via Celoria 16 MilanoI-20133 Italy Dipartimento di Fisica e Scienze della Terra Università degli Studi di Ferrara Via Saragat 1 FerraraI-44122 Italy INAF-Osservatorio Astronomico di Capodimonte Via Moiariello 16 Napoli80131 Italy Astronomy Unit Department of Physics University of Trieste via Tiepolo 11 TriesteI-34131 Italy Dipartimento di Fisica e Astronomia "Augusto Righi" Alma Mater Studiorum Università di Bologna via Gobetti 93/2 BolognaI-40129 Italy INAF - IASF Milano via A. Corti 12 MilanoI-20133 Italy International Centre for Radio Astronomy Research University of Western Australia 35 Stirling Highway CrawleyWA6009 Australia New York University Abu Dhabi PO Box Abu Dhabi129188 United Arab Emirates New York University Abu Dhabi United Arab Emirates Max-Planck-Institut für Astronomie Königstuhl 17 HeidelbergD-69117 Germany FiscianoI–84084 Italy Department of Astronomy Yale University New HavenCT06511 United States Department of Physics Yale University New HavenCT06520 United States ICSC - Italian Research Center on High Performance Computing Big Data and Quantum Computing Italy

Context. Previous studies have revealed that the estimated probability of galaxy-galaxy strong lensing in observed galaxy clusters exceeds the expectations from the Λ Cold Dark Matter cosmological model by one order of magnitude. Aims. We aim to understand the origin of this excess by analyzing a larger set of simulated galaxy clusters, and investigating how the theoretical expectations vary under different adopted prescriptions and numerical implementations of star formation and feedback in simulations. Methods. We performed a ray-tracing analysis of 324 galaxy clusters from the Three Hundred project, comparing the Gadget-X and Gizmo-Simba runs. These simulations, which start from the same initial conditions, were performed with different implementations of hydrodynamics and galaxy formation models tailored to match different observational properties of the intracluster medium and cluster galaxies. Results. We find that galaxies in the Gizmo-Simba simulations develop denser stellar cores than their Gadget-X counterparts. Consequently, their probability for galaxy-galaxy strong lensing is higher by a factor of ∼ 3. This increment is still insufficient to fill the gap with observations as a discrepancy by a factor ∼ 4 still persists. In addition, we find that several simulated galaxies have Einstein radii that are too large compared to observations. Conclusions. We conclude that a persistent excess of galaxy-galaxy strong lensing exists in observed galaxy clusters. The origin of this discrepancy with theoretical predictions is still unexplained in the framework of the cosmological hydrodynamical simulations. This might signal a hitherto unknown issue with either the simulation methods or our assumptions regarding the standard cosmological model. Copyright © 2023, The Authors. All rights reserved.

关键词： Galaxies

The Wide-field Spectroscopic Telescope (WST) Science White Paper

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arXiv 2024年

作者： Mainieri, Vincenzo Anderson, Richard I. Brinchmann, Jarle Cimatti, Andrea Ellis, Richard Hill, Vanessa Kneib, Jean-Paul McLeod, Anna Opitom, Cyrielle Roth, Martin M. Sáez, Paula Sánchez Smiljanic, Rodolfo Tolstoy, Eline Bacon, Roland Randich, Sofia Pasquini, Luca Barsanti, Stefania Bryant, Julia Bryson, Ian Casali, Mark Colless, Matthew Couch, Warrick Danielski, Camilla Dierickx, Philippe Driver, Simon Fontana, Adriano Garilli, Bianca de Jong, Roelof S. Lee, David Lehnert, Matt Magrini, Laura Montet, Ben Sanchez-Janssen, Ruben Pandey-Pommier, Mamta Sargent, Mark Schipani, Pietro Steinmetz, Matthias Travouillon, Tony Tresse, Laurence Vernet, Joël Yeche, Christophe Ziegler, Bodo Audard, Marc Arévalo, Patricia Bayo Aran, Amelia M. Bisero, Sofia Bisogni, Susanna Blondin, Stéphane Bonito, Rosaria Branchesi, Marica Catelan, Márcio D'Ammando, Filippo Dainotti, Maria G. De Cia, Annalisa Dhawan, Suhail Dupletsa, Ulyana Hazra, Nandini Ilić, Dragana Ivanov, Valentin D. Izzo, Luca Kovačević, Andjelka B. Kuncarayakti, Hanindyo Kwon, Yuna La Forgia, Fiorangela Lazzarin, Monica Lira, Paulina Loffredo, Eleonora Maguire, Kate Majidi, Fatemeh Z. Marconi, Marcella McGee, Sean Migliorini, Alessandra Minniti, Dante Nicholl, Matt Onori, Francesca Pala, Anna F. Panda, Swayamtrupta Pawlak, Michal Pessi, Priscila J. Popović, Luka Č. Smith, Graham P. Vergani, Susanna D. Vietri, Giustina Ye, Quanzhi Zafar, Tayyaba Matsuno, Tadafumi Kordopatis, Georges Annibali, Francesca Bayo, Amelia Bellazzini, Michele Beltran, Maria Teresa Berni, Leda Bianchi, Simone Biazzo, Katia Bland-Hawthorn, Joss Boffin, Henri M.J. Bono, Giuseppe Bowman, Dominic Braga, Vittorio F. Bragaglia, Angela Brucalassi, Anna Busà, Innocenza Casali, Giada Casasola, Viviana Castro, Norberto Cavallo, Lorenzo Chiappini, Cristina Colzi, Laura Damiani, Francesco da Silva, Ronaldo D'Orazi, Valentina Escorza, Ana Fabrizio, Michele Fiorentino, Giuliana Fontani, Francesco François, Patrick Galindo-Guil, Francisco J. Galli, Daniele Garcia-Rojas, Jorge Guarcello, Mario Giuseppe Helmi, Am European Southern Observatory Karl-Schwarzschild-Strasse 2 Garching bei München85748 Germany Switzerland Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Portugal Dipartimento di Fisica e Astronomia "Augusto Righi" Alma Mater Studiorum Università di Bologna Italy Department of Physics and Astronomy University College London United Kingdom Observatoire de la Côte d'Azur Université Côte d'Azur CNRS Laboratoire Lagrange France Centre for Extragalactic Astronomy Department of Physics Durham University United Kingdom Institute for Computational Cosmology Department of Physics University of Durham United Kingdom Institute for Astronomy University of Edinburgh United Kingdom Germany Nicolaus Copernicus Astronomical Center Polish Academy of Sciences Poland Kapteyn Astronomical Institute University of Groningen Netherlands France INAF - Osservatorio Astrofisico di Arcetri Italy Stockholm University Sweden INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Italy Universidad de Valparaíso Chile University of Geneva Switzerland Research School of Astronomy and Astrophysics Australian National University CanberraACT2611 Australia Australia Instituto de Astrofísica de Canarias Spain Universidad de La Laguna Spain SISSA - Scuola Internazionale Superiore di Studi Avanzati Italy University of Florence Italy INAF - Osservatorio Astronomico di Roma Italy GEPI Observatoire de Paris Universite PSL CNRS France INAF Istituto di Astrofisica Spaziale e Fisica cosmica Milano Italy Sydney Institute for Astronomy School of Physics The University of Sydney Australia Aix Marseille Univ CNRS CNES LAM France INAF - Osservatorio Astronomico di Palermo Italy University of Rome Tor Vergata Italy Newcastle University United Kingdom Italy UK Astronomy Technology Ctr. Royal Observatory Edinburgh United Kingdom INAF OACT Italy Dipartimento di Fisica Università degli Studi di Torino Italy Istituto Nazionale di Fisica Nucleare INFN Sezione di

The WST is proposed as a new facility dedicated to the efficient delivery of spectroscopic surveys and this white paper summarises the initial concept as well as the corresponding science cases. It will provide an end-to-end service from the preparation of surveys to the delivery of high-quality calibrated science data product. Uniquely, it will have the ability to simultaneously deliver fibre-fed multi-object spectroscopy over a large field of view (MOS) and integral field imaging spectroscopy of a central field of 3 × 3 arcmin2 (IFS). WST will fill a crucial gap in the astronomical landscape and will allow full exploitation of major current and upcoming ground and space-based facilities. WST will address outstanding scientific questions in the areas of cosmology;galaxy assembly, evolution, and enrichment, including our own Milky Way;origin of stars and planets;time domain and multi-messenger astrophysics. WST features a 12 meter aperture telescope that covers the UV to the H band and operates in seeing limited conditions. Its field of view (FoV) of 3.1 deg2 will be the largest of any telescope equipped with a MOS. In particular, its FoV is 2.5 times larger than PFS@Subaru and a remarkable 22 times larger than MOONS@VLT. In addition, the WST has a substantial aperture, twice as large (100 square metres) as its 8 meter class competitors. A central circular area with a diameter of 13 arcmin is available for simultaneous IFS observations. Within this area, the IFS with a FoV of 3 × 3 arcmin2 (9 times larger than MUSE@VLT) can be utilised simultaneously with the MOS. In addition, the IFS can be used to mosaic a larger area within the 13 arcmin circle (an area larger than the entire FoV of the ELT) while the MOS positioner can perform multiple configurations. The WST operational model will also implement target of opportunity (ToO) operations at both the telescope and MOS fibre levels to support the time domain science cases. The demand for a facility dedicated to spect

关键词： Telescopes

Stochastic modified equations and dynamics of stochastic gradient algorithms I: Mathematical foundations

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arXiv 2018年

作者： Li, Qianxiao Tai, Cheng Weinan, E. Institute of High Performance Computing Agency for Science Technology and Research 1 Fusionopolis Way Connexis North138632 Singapore Beijing Institute of Big Data Research Peking University Beijing100080 China Princeton University PrincetonNJ08544 United States

关键词： Stochastic systems

The GAPS program at TNG XLVII: The unusual formation history of V1298 Tau

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arXiv 2023年

作者： Turrini, D. Marzari, F. Polychroni, D. Claudi, R. Desidera, S. Mesa, D. Pinamonti, M. Sozzetti, A. Mascareño, A. Suárez Damasso, M. Benatti, S. Malavolta, L. Micela, G. Zinzi, A. Béjar, V.J.S. Biazzo, K. bignamini, A. Bonavita, M. Borsa, F. Del Burgo, C. Chauvin, G. Delorme, P. Hernández, J.I. González Gratton, R. Hagelberg, J. Janson, M. Langlois, M. Lanza, A.F. Lazzoni, C. Lodieu, N. Maggio, A. Mancini, L. Molinari, E. Molinaro, M. Murgas, F. Nardiello, D. Inaf - Osservatorio Astrofisico di Torino via Osservatorio 20 Pino TorineseI-10025 Italy Icsc National Research Centre for High Performance Computing Big Data and Quantum Computing Via Magnanelli 2 Casalecchio di RenoI-40033 Italy Inaf - Istituto di Astrofisica e Planetologia Spaziali via Fosso del Cavaliere 100 RomaI-00133 Italy Dipartimento di Fisica e Astronomia Università di Padova Via Marzolo 8 PadovaI-35121 Italy Inaf - Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5 PadovaI-35122 Italy Inaf - Osservatorio Astronomico di Trieste Via G. B. Tiepolo 11 TriesteI-34143 Italy Inaf - Osservatorio Astronomico di Palermo Piazza del Parlamento 1 Palermo90134 Italy Space Science Data Center - Asi Via del Politecnico snc Roma00133 Italy Instituto de Astrofísica de Canarias Tenerife La LagunaE-38200 Spain Universidad de la Laguna Dept. Astrofísica Tenerife La LagunaE-38206 Spain Inaf - Osservatorio Astronomico di Roma Via Frascati 33 Monte Porzio CatoneI-00040 Italy School of Physical Sciences The Open University Walton Hall Milton KeynesMK7 6AA United Kingdom Supa Institute for Astronomy University of Edinburgh Blackford Hill EdinburghEH9 3HJ United Kingdom Inaf - Osservatorio Astronomico di Brera Via E. Bianchi 46 MerateI-23087 Italy Instituto Nacional de Astrofísica Óptica y Electrónica Luis Enrique Erro 1 Sta. Ma. Tonantzintla Puebla Mexico Universitè Côte d'Azur Observatoire de la Côte d'Azur Cnrs Laboratoire Lagrange Nice France Universitè Grenoble Alpes Cnrs Ipag Grenoble38000 France Geneva Observatory University of Geneva Chemin Pegasi 51 Versoix1290 Switzerland Department of Astronomy Stockholm University AlbaNova University Center Stockholm10691 Sweden Cral Umr 5574 Cnrs Université de Lyon Ecole Normale Supérieure de Lyon 46 allée d'Italie Lyon69364 Cedex 07 France Inaf - Osservatorio Astrofisico di Catania Via Santa Sofia 78 Catania95123 Italy Department of Physics and Astronomy University of Ex

Context. Observational data from space and ground-based campaigns reveal that the 10-30 Ma old V1298 Tau star hosts a compact and massive system of four planets. Mass estimates are available for the two outer giant planets and point to unexpectedly high densities for their young ages. Aims. We investigate the formation of these two outermost giant planets, V1298 Tau b and e, and the present dynamical state of V1298 Tau's global architecture to shed light on the history of this young and peculiar extrasolar system. Methods. We perform detailed N-body simulations to explore the link between the densities of V1298 Tau b and e and their migration and accretion of planetesimals within the native circumstellar disk. We combine N-body simulations and the normalized angular momentum deficit (NAMD) analysis of the architecture to characterize V1298 Tau's dynamical state and connect it to the formation history of the system. We search for outer planetary companions to constrain V1298 Tau's planetary architecture and the extension of its primordial circumstellar disk. Results. The high densities of V1298 Tau b and e suggest they formed quite distant from their host star, likely beyond the CO2snowline. The higher nominal density of V1298 Tau e suggests it formed farther out than V1298 Tau b. The current architecture of V1298 Tau is not characterized by resonant chains. Planet-planet scattering with an outer giant planet is the most likely cause for the instability, but our search for outer companions using SPHERE and GAIA observations can currently exclude only the presence of planets more massive than 2 MJ. Conclusions. The most plausible scenario for V1298 Tau's formation is that the system is formed by convergent migration and resonant trapping of planets born in a compact and plausibly massive disk. The migration of V1298 Tau b and e leaves in its wake a dynamically excited protoplanetary disk and naturally creates the conditions for the later breaking of the resonant chain

关键词： Stars

A mean-field optimal control formulation of deep learning

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arXiv 2018年

作者： Weinan, E. Han, Jiequn Li, Qianxiao Princeton University PrincetonNJ08544 United States Beijing Institute of Big Data Research and Peking University Beijing100871 China Institute of High Performance Computing Agency for Science Technology and Research Connexis North 1 Fusionopolis Way Singapore138632 Singapore

Recent work linking deep neural networks and dynamical systems opened up new avenues to analyze deep learning. In particular, it is observed that new insights can be obtained by recasting deep learning as an optimal control problem on difference or differential equations. However, the mathematical aspects of such a formulation have not been systematically explored. This paper introduces the mathematical formulation of the population risk minimization problem in deep learning as a mean-field optimal control problem. Mirroring the development of classical optimal control, we state and prove optimality conditions of both the Hamilton-Jacobi-Bellman type and the Pontryagin type. These mean-field results reflect the probabilistic nature of the learning problem. In addition, by appealing to the mean-field Pontryagin's maximum principle, we establish some quantitative relationships between population and empirical learning problems. This serves to establish a mathematical foundation for investigating the algorithmic and theoretical connections between optimal control and deep learning. Copyright © 2018, The Authors. All rights reserved.

关键词： Optimal control systems

Design Evaluation of a performance Analysis Trace Repository

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Procedia Computer Science 2017年 108卷 2190-2199页

作者： Richard Grunzke Maximilian Neumann Thomas Ilsche Volker Hartmann Thomas Jejkal Rainer Stotzka Andreas Knüpfer Wolfgang E. Nagel Center for Information Services and High Performance Computing Technische Universität Dresden Dresden Germany Institute for Data Processing and Electronics Karlsruhe Institute of Technology Karlsruhe Germany

Parallel and high performance computing experts are obsessed with performance and scalability. performance analysis and tuning are important and complex but there are a number of software tools to support this. One methodology is the detailed recording of parallel runtime behavior in event traces and their subsequent analysis. This regularly produces very large data sets with their own challenges for handling and data management. This paper evaluates the utilization of the MASi research data management service as a trace repository to store, manage, and find traces in an efficient and usable way. First, we give an introduction to trace technologies in general, metadata in OTF2 traces specifically, and the MASi research data management service. Then, the trace repository is described with its potential for both performance analysts and parallel tool developers, followed with how we implemented it using existing metadata and how it can utilized. Finally, we give an outlook on how we plan to put the repository into productive use for the benefit of researchers using traces.

关键词： performance Analysis data Repository Metadata Extraction

Unveiling latent behaviors of video viewers with cross-platform information 27

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Unveiling latent behaviors of video viewers with cross-platf...

27th ACM Workshop on Network and Operating Systems Support for Digital Audio and Video, NOSSDAV 2017

作者： Gu, Xuhong Zhou, Yipeng Wu, Di Chan, Terence H. Chen, Min School of Data and Computer Science Sun Yat-sen University China Institute for Telecommunications Research University of South Australia Australia Guangdong Province Key Laboratory of Big Data Analysis and Processing Sun Yat-sen University China Collaborative Innovation Center of High Performance Computing National University of Defense Technology China School of Computer Science and Technology Huazhong University of Science and Technology China

ISBN: (纸本)9781450350037

The online video streaming service is of huge market values with billions of worldwide users. For online video providers, e.g., Net-flix, Youku, the crucial question is how to understand users' view behaviors and preferences because this knowledge is important for their business operation. Existing solutions mainly rely on analyzing users' historical view records, which however are not always available, especially for new videos and unprovided videos. Different from existing solutions, we propose to infer user behaviors and preferences by jointly analyzing data collected from multiple platforms (e.g., video streaming systems, video databases, etc.). In particular, we use the movie data crawled from a leading video streaming system (i.e., Youku), and a well-known video database in China (i.e, Douban) for this study. Our investigation points out that movie quality (evaluated in terms of Douban scores) and release date jointly influence viewers' preferences. In addition, we reveal a series of user behaviors, e.g., users are reluctant to post comments or ratings for movies they do not like, and user eyeballs are heavily captured by new movies. Understanding of these user behaviors covered by this study is essential for video recommendation and video popularity prediction which can benefit video procurement and advertisement campaign. © 2017 ACM.

关键词： Video streaming