Rajeev Motwani
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Interactive Proof Systems and Alternating Time-Space Complexity
Theoretical Computer Science 113 (1993) 55-73 55 Elsevier Interactive proof systems and alternating time-space complexity Lance Fortnow” and Carsten Lund** Department of Computer Science, Unicersity of Chicago. 1100 E. 58th Street, Chicago, IL 40637, USA Abstract Fortnow, L. and C. Lund, Interactive proof systems and alternating time-space complexity, Theoretical Computer Science 113 (1993) 55-73. We show a rough equivalence between alternating time-space complexity and a public-coin interactive proof system with the verifier having a polynomial-related time-space complexity. Special cases include the following: . All of NC has interactive proofs, with a log-space polynomial-time public-coin verifier vastly improving the best previous lower bound of LOGCFL for this model (Fortnow and Sipser, 1988). All languages in P have interactive proofs with a polynomial-time public-coin verifier using o(log’ n) space. l All exponential-time languages have interactive proof systems with public-coin polynomial-space exponential-time verifiers. To achieve better bounds, we show how to reduce a k-tape alternating Turing machine to a l-tape alternating Turing machine with only a constant factor increase in time and space. 1. Introduction In 1981, Chandra et al. [4] introduced alternating Turing machines, an extension of nondeterministic computation where the Turing machine can make both existential and universal moves. In 1985, Goldwasser et al. [lo] and Babai [l] introduced interactive proof systems, an extension of nondeterministic computation consisting of two players, an infinitely powerful prover and a probabilistic polynomial-time verifier. The prover will try to convince the verifier of the validity of some statement. -
Challenges in Web Search Engines
Challenges in Web Search Engines Monika R. Henzinger Rajeev Motwani* Craig Silverstein Google Inc. Department of Computer Science Google Inc. 2400 Bayshore Parkway Stanford University 2400 Bayshore Parkway Mountain View, CA 94043 Stanford, CA 94305 Mountain View, CA 94043 [email protected] [email protected] [email protected] Abstract or a combination thereof. There are web ranking optimiza• tion services which, for a fee, claim to place a given web site This article presents a high-level discussion of highly on a given search engine. some problems that are unique to web search en• Unfortunately, spamming has become so prevalent that ev• gines. The goal is to raise awareness and stimulate ery commercial search engine has had to take measures to research in these areas. identify and remove spam. Without such measures, the qual• ity of the rankings suffers severely. Traditional research in information retrieval has not had to 1 Introduction deal with this problem of "malicious" content in the corpora. Quite certainly, this problem is not present in the benchmark Web search engines are faced with a number of difficult prob• document collections used by researchers in the past; indeed, lems in maintaining or enhancing the quality of their perfor• those collections consist exclusively of high-quality content mance. These problems are either unique to this domain, or such as newspaper or scientific articles. Similarly, the spam novel variants of problems that have been studied in the liter• problem is not present in the context of intranets, the web that ature. Our goal in writing this article is to raise awareness of exists within a corporation. -
The Multiplicative Weights Update Method: a Meta Algorithm and Applications
The Multiplicative Weights Update Method: a Meta Algorithm and Applications Sanjeev Arora∗ Elad Hazan Satyen Kale Abstract Algorithms in varied fields use the idea of maintaining a distribution over a certain set and use the multiplicative update rule to iteratively change these weights. Their analysis are usually very similar and rely on an exponential potential function. We present a simple meta algorithm that unifies these disparate algorithms and drives them as simple instantiations of the meta algo- rithm. 1 Introduction Algorithms in varied fields work as follows: a distribution is maintained on a certain set, and at each step the probability assigned to i is multi- plied or divided by (1 + C(i)) where C(i) is some kind of “payoff” for element i. (Rescaling may be needed to ensure that the new values form a distribution.) Some examples include: the Ada Boost algorithm in ma- chine learning [FS97]; algorithms for game playing studied in economics (see below), the Plotkin-Shmoys-Tardos algorithm for packing and covering LPs [PST91], and its improvements in the case of flow problems by Young, Garg-Konneman, and Fleischer [You95, GK98, Fle00]; Impagliazzo’s proof of the Yao XOR lemma [Imp95], etc. The analysis of the running time uses a potential function argument and the final running time is proportional to 1/2. It has been clear to most researchers that these results are very similar, see for instance, Khandekar’s PhD thesis [Kha04]. Here we point out that these are all instances of the same (more general) algorithm. This meta ∗This project supported by David and Lucile Packard Fellowship and NSF grant CCR- 0205594. -
Oral History Interview with Severo Ornstein and Laura Gould
An Interview with SEVERO ORNSTEIN AND LAURA GOULD OH 258 Conducted by Bruce H. Bruemmer on 17 November 1994 Woodside, CA Charles Babbage Institute Center for the History of Information Processing University of Minnesota, Minneapolis Severo Ornstein and Laura Gould Interview 17 November 1994 Abstract Ornstein and Gould discuss the creation and expansion of Computer Professionals for Social Responsibility (CPSR). Ornstein recalls beginning a listserve at Xerox PARC for those concerned with the threat of nuclear war. Ornstein and Gould describe the movement of listserve participants from e-mail discussions to meetings and forming a group concerned with computer use in military systems. The bulk of the interview traces CPSR's organizational growth, fundraising, and activities educating the public about computer-dependent weapons systems such as proposed in the Strategic Defense Initiative (SDI). SEVERO ORNSTEIN AND LAURA GOULD INTERVIEW DATE: November 17, 1994 INTERVIEWER: Bruce H. Bruemmer LOCATION: Woodside, CA BRUEMMER: As I was going through your oral history interview I began to wonder about your political background and political background of the people who had started the organization. Can you characterize that? You had mentioned in your interview that you had done some antiwar demonstrations and that type of thing which is all very interesting given also your connection with DARPA. ORNSTEIN: Yes, most of the people at DARPA knew this. DARPA was not actually making bombs, you understand, and I think in the interview I talked about my feelings about DARPA at the time. I was strongly against the Vietnam War and never hid it from anyone. I wore my "Resist" button right into the Pentagon and if they didn't like it they could throw me out. -
Backmatter In
Appendices Bibliography This book is a little like the previews of coming attractions at the movies; it's meant to whet your appetite in several directions, without giving you the complete story about anything. To ®nd out more, you'll have to consult more specialized books on each topic. There are a lot of books on computer programming and computer science, and whichever I chose to list here would be out of date by the time you read this. Instead of trying to give current references in every area, in this edition I'm listing only the few most important and timeless books, plus an indication of the sources I used for each chapter. Computer science is a fast-changing ®eld; if you want to know what the current hot issues are, you have to read the journals. The way to start is to join the Association for Computing Machinery, 1515 Broadway, New York, NY 10036. If you are a full-time student you are eligible for a special rate for dues, which as I write this is $25 per year. (But you should write for a membership application with the current rates.) The Association publishes about 20 monthly or quarterly periodicals, plus the newsletters of about 40 Special Interest Groups in particular ®elds. 341 Read These! If you read no other books about computer science, you must read these two. One is an introductory text for college computer science students; the other is intended for a nonspecialist audience. Abelson, Harold, and Gerald Jay Sussman with Julie Sussman, Structure and Interpretation of Computer Programs, MIT Press, Second Edition, 1996. -
FOCS 2005 Program SUNDAY October 23, 2005
FOCS 2005 Program SUNDAY October 23, 2005 Talks in Grand Ballroom, 17th floor Session 1: 8:50am – 10:10am Chair: Eva´ Tardos 8:50 Agnostically Learning Halfspaces Adam Kalai, Adam Klivans, Yishay Mansour and Rocco Servedio 9:10 Noise stability of functions with low influences: invari- ance and optimality The 46th Annual IEEE Symposium on Elchanan Mossel, Ryan O’Donnell and Krzysztof Foundations of Computer Science Oleszkiewicz October 22-25, 2005 Omni William Penn Hotel, 9:30 Every decision tree has an influential variable Pittsburgh, PA Ryan O’Donnell, Michael Saks, Oded Schramm and Rocco Servedio Sponsored by the IEEE Computer Society Technical Committee on Mathematical Foundations of Computing 9:50 Lower Bounds for the Noisy Broadcast Problem In cooperation with ACM SIGACT Navin Goyal, Guy Kindler and Michael Saks Break 10:10am – 10:30am FOCS ’05 gratefully acknowledges financial support from Microsoft Research, Yahoo! Research, and the CMU Aladdin center Session 2: 10:30am – 12:10pm Chair: Satish Rao SATURDAY October 22, 2005 10:30 The Unique Games Conjecture, Integrality Gap for Cut Problems and Embeddability of Negative Type Metrics Tutorials held at CMU University Center into `1 [Best paper award] Reception at Omni William Penn Hotel, Monongahela Room, Subhash Khot and Nisheeth Vishnoi 17th floor 10:50 The Closest Substring problem with small distances Tutorial 1: 1:30pm – 3:30pm Daniel Marx (McConomy Auditorium) Chair: Irit Dinur 11:10 Fitting tree metrics: Hierarchical clustering and Phy- logeny Subhash Khot Nir Ailon and Moses Charikar On the Unique Games Conjecture 11:30 Metric Embeddings with Relaxed Guarantees Break 3:30pm – 4:00pm Ittai Abraham, Yair Bartal, T-H. -
The Evolution of Lisp
1 The Evolution of Lisp Guy L. Steele Jr. Richard P. Gabriel Thinking Machines Corporation Lucid, Inc. 245 First Street 707 Laurel Street Cambridge, Massachusetts 02142 Menlo Park, California 94025 Phone: (617) 234-2860 Phone: (415) 329-8400 FAX: (617) 243-4444 FAX: (415) 329-8480 E-mail: [email protected] E-mail: [email protected] Abstract Lisp is the world’s greatest programming language—or so its proponents think. The structure of Lisp makes it easy to extend the language or even to implement entirely new dialects without starting from scratch. Overall, the evolution of Lisp has been guided more by institutional rivalry, one-upsmanship, and the glee born of technical cleverness that is characteristic of the “hacker culture” than by sober assessments of technical requirements. Nevertheless this process has eventually produced both an industrial- strength programming language, messy but powerful, and a technically pure dialect, small but powerful, that is suitable for use by programming-language theoreticians. We pick up where McCarthy’s paper in the first HOPL conference left off. We trace the development chronologically from the era of the PDP-6, through the heyday of Interlisp and MacLisp, past the ascension and decline of special purpose Lisp machines, to the present era of standardization activities. We then examine the technical evolution of a few representative language features, including both some notable successes and some notable failures, that illuminate design issues that distinguish Lisp from other programming languages. We also discuss the use of Lisp as a laboratory for designing other programming languages. We conclude with some reflections on the forces that have driven the evolution of Lisp. -
Interactive Proofs
Interactive proofs April 12, 2014 [72] L´aszl´oBabai. Trading group theory for randomness. In Proc. 17th STOC, pages 421{429. ACM Press, 1985. doi:10.1145/22145.22192. [89] L´aszl´oBabai and Shlomo Moran. Arthur-Merlin games: A randomized proof system and a hierarchy of complexity classes. J. Comput. System Sci., 36(2):254{276, 1988. doi:10.1016/0022-0000(88)90028-1. [99] L´aszl´oBabai, Lance Fortnow, and Carsten Lund. Nondeterministic ex- ponential time has two-prover interactive protocols. In Proc. 31st FOCS, pages 16{25. IEEE Comp. Soc. Press, 1990. doi:10.1109/FSCS.1990.89520. See item 1991.108. [108] L´aszl´oBabai, Lance Fortnow, and Carsten Lund. Nondeterministic expo- nential time has two-prover interactive protocols. Comput. Complexity, 1 (1):3{40, 1991. doi:10.1007/BF01200056. Full version of 1990.99. [136] Sanjeev Arora, L´aszl´oBabai, Jacques Stern, and Z. (Elizabeth) Sweedyk. The hardness of approximate optima in lattices, codes, and systems of linear equations. In Proc. 34th FOCS, pages 724{733, Palo Alto CA, 1993. IEEE Comp. Soc. Press. doi:10.1109/SFCS.1993.366815. Conference version of item 1997:160. [160] Sanjeev Arora, L´aszl´oBabai, Jacques Stern, and Z. (Elizabeth) Sweedyk. The hardness of approximate optima in lattices, codes, and systems of linear equations. J. Comput. System Sci., 54(2):317{331, 1997. doi:10.1006/jcss.1997.1472. Full version of 1993.136. [111] L´aszl´oBabai, Lance Fortnow, Noam Nisan, and Avi Wigderson. BPP has subexponential time simulations unless EXPTIME has publishable proofs. In Proc. -
Distance-Sensitive Hashing∗
Distance-Sensitive Hashing∗ Martin Aumüller Tobias Christiani IT University of Copenhagen IT University of Copenhagen [email protected] [email protected] Rasmus Pagh Francesco Silvestri IT University of Copenhagen University of Padova [email protected] [email protected] ABSTRACT tight up to lower order terms. In particular, we extend existing Locality-sensitive hashing (LSH) is an important tool for managing LSH lower bounds, showing that they also hold in the asymmetric high-dimensional noisy or uncertain data, for example in connec- setting. tion with data cleaning (similarity join) and noise-robust search (similarity search). However, for a number of problems the LSH CCS CONCEPTS framework is not known to yield good solutions, and instead ad hoc • Theory of computation → Randomness, geometry and dis- solutions have been designed for particular similarity and distance crete structures; Data structures design and analysis; • Informa- measures. For example, this is true for output-sensitive similarity tion systems → Information retrieval; search/join, and for indexes supporting annulus queries that aim to report a point close to a certain given distance from the query KEYWORDS point. locality-sensitive hashing; similarity search; annulus query In this paper we initiate the study of distance-sensitive hashing (DSH), a generalization of LSH that seeks a family of hash functions ACM Reference Format: Martin Aumüller, Tobias Christiani, Rasmus Pagh, and Francesco Silvestri. such that the probability of two points having the same hash value is 2018. Distance-Sensitive Hashing. In Proceedings of 2018 International Confer- a given function of the distance between them. More precisely, given ence on Management of Data (PODS’18). -
Arxiv:2102.08942V1 [Cs.DB]
A Survey on Locality Sensitive Hashing Algorithms and their Applications OMID JAFARI, New Mexico State University, USA PREETI MAURYA, New Mexico State University, USA PARTH NAGARKAR, New Mexico State University, USA KHANDKER MUSHFIQUL ISLAM, New Mexico State University, USA CHIDAMBARAM CRUSHEV, New Mexico State University, USA Finding nearest neighbors in high-dimensional spaces is a fundamental operation in many diverse application domains. Locality Sensitive Hashing (LSH) is one of the most popular techniques for finding approximate nearest neighbor searches in high-dimensional spaces. The main benefits of LSH are its sub-linear query performance and theoretical guarantees on the query accuracy. In this survey paper, we provide a review of state-of-the-art LSH and Distributed LSH techniques. Most importantly, unlike any other prior survey, we present how Locality Sensitive Hashing is utilized in different application domains. CCS Concepts: • General and reference → Surveys and overviews. Additional Key Words and Phrases: Locality Sensitive Hashing, Approximate Nearest Neighbor Search, High-Dimensional Similarity Search, Indexing 1 INTRODUCTION Finding nearest neighbors in high-dimensional spaces is an important problem in several diverse applications, such as multimedia retrieval, machine learning, biological and geological sciences, etc. For low-dimensions (< 10), popular tree-based index structures, such as KD-tree [12], SR-tree [56], etc. are effective, but for higher number of dimensions, these index structures suffer from the well-known problem, curse of dimensionality (where the performance of these index structures is often out-performed even by linear scans) [21]. Instead of searching for exact results, one solution to address the curse of dimensionality problem is to look for approximate results. -
Hierarchical Clustering with Global Objectives: Approximation Algorithms and Hardness Results
HIERARCHICAL CLUSTERING WITH GLOBAL OBJECTIVES: APPROXIMATION ALGORITHMS AND HARDNESS RESULTS ADISSERTATION SUBMITTED TO THE DEPARTMENT OF COMPUTER SCIENCE AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Evangelos Chatziafratis June 2020 © 2020 by Evangelos Chatziafratis. All Rights Reserved. Re-distributed by Stanford University under license with the author. This work is licensed under a Creative Commons Attribution- Noncommercial 3.0 United States License. http://creativecommons.org/licenses/by-nc/3.0/us/ This dissertation is online at: http://purl.stanford.edu/bb164pj1759 ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Tim Roughgarden, Primary Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Moses Charikar, Co-Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Li-Yang Tan I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Gregory Valiant Approved for the Stanford University Committee on Graduate Studies. Stacey F. Bent, Vice Provost for Graduate Education This signature page was generated electronically upon submission of this dissertation in electronic format. -
Input-Oblivious Proof Systems and a Uniform Complexity Perspective on P/Poly
Electronic Colloquium on Computational Complexity, Report No. 23 (2011) Input-Oblivious Proof Systems and a Uniform Complexity Perspective on P/poly Oded Goldreich∗ and Or Meir† Department of Computer Science Weizmann Institute of Science Rehovot, Israel. February 16, 2011 Abstract We initiate a study of input-oblivious proof systems, and present a few preliminary results regarding such systems. Our results offer a perspective on the intersection of the non-uniform complexity class P/poly with uniform complexity classes such as NP and IP. In particular, we provide a uniform complexity formulation of the conjecture N P 6⊂ P/poly and a uniform com- plexity characterization of the class IP∩P/poly. These (and similar) results offer a perspective on the attempt to prove circuit lower bounds for complexity classes such as NP, PSPACE, EXP, and NEXP. Keywords: NP, IP, PCP, ZK, P/poly, MA, BPP, RP, E, NE, EXP, NEXP. Contents 1 Introduction 1 1.1 The case of NP ....................................... 1 1.2 Connection to circuit lower bounds ............................ 2 1.3 Organization and a piece of notation ........................... 3 2 Input-Oblivious NP-Proof Systems (ONP) 3 3 Input-Oblivious Interactive Proof Systems (OIP) 5 4 Input-Oblivious Versions of PCP and ZK 6 4.1 Input-Oblivious PCP .................................... 6 4.2 Input-Oblivious ZK ..................................... 7 Bibliography 10 ∗Partially supported by the Israel Science Foundation (grant No. 1041/08). †Research supported by the Adams Fellowship Program of the Israel Academy of Sciences and Humanities. ISSN 1433-8092 1 Introduction Various types of proof systems play a central role in the theory of computation.