May 2010 - talks - lists.cs.princeton.edu

Novel User Interfaces for Audio and Music Computing: Friday 5/28, 2-3pm
by Rebecca A. Fiebrink 18 May '10

18 May '10

Hi everyone, Joern Loviscach is a prolific researcher in music technology, HCI, machine learning, and beyond. He's coming next Friday to give a talk at Princeton, so please come meet him and hear about his work! Abstract & bio are below. Rebecca *** Novel User Interfaces for Audio and Music Computing Friday May 28, 2010, 2-3pm Woolworth Music Building, Room 101 Many tasks in digital music making, audio retrieval, and audio processing become chores, with only few occasions for inspiration and serendipity. This talk is a show & tell presentation of a range of prototypes of enhanced user interfaces developed by the presenter and his collaborators to bring back the fun, such as: * Acoustic and visual support for finding music and sounds * Improved visual feedback in music sequencers and digital audio workstations * Modified on-screen fader controls, modified mice, and color-changing buttons used as controllers for music software * Digital music making with the Wii remote controller, a loudspeaker, and other items, among them a bass guitar For examples, see http://www.youtube.com/watch?v=eiwj7Td7Pec http://www.youtube.com/watch?v=UuUjf-c6L6U http://www.youtube.com/watch?v=fTLkafr2Xp8 Bio Joern Loviscach ( www.j3L7h.de ) is a professor of technical mathematics and computer engineering at Fachhochschule Bielefeld (University of Appleid Sciences), Germany. In his research, he aims at connecting human-computer interaction, visual computing, signal processing, machine learning, and electronics. He is a regular contributor to conferences such as SIGGRAPH, Eurographics, AES Convention, and ICMC. In addition, he has published numerous chapters in book series such as Game Programming Gems and ShaderX Programming.

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W Josephson preFPO
by Melissa Lawson 18 May '10

18 May '10

William Josephson will present his preFPO on Tuesday May 25 at 1:30PM in Room 402. The members of his committee are: Kai Li, advisor; Brian Kernighan and Jen Rexford, readers; Mike Freedman and Doug Clark, nonreaders. Everyone is invited to attend his talk. His abstract follows below. -------------------------------------- Title: Rethinking The Storage Software Stack for Flash Memory Flash memory has recently emerged as an important component of the storage infrastructure in the data center, but presents several unique challenges to storage system designers: individual blocks must be erased before they can be rewritten, block erasure is time consuming, and individual blocks may be erased only a limited number of times. By combining hardware parallelism and a log-structured approach, state of the art flash storage systems can deliver two to three orders of mangitude more I/O operations per second than existing high-performance fibre channel disk drives. Despite the emergence of state of the art solid state disks, the storage software stack has changed little and is still optimized for magnetic disks; the basic abstraction remains a linear array of fix-sized blocks together with a very large DRAM cache to convert user I/O to a smaller number of large I/O transfers. In this talk, we first examine the impact SSDs have had on the utility of the buffer cache. As SSD performance and density improves, the value of very large DRAM based buffer caches declines. We examine the change in tradeoffs through database buffer cache traces and simulation and offer some simple heuristics to take advantage of these changes. Second, we propose a richer interface more suitable for solid-state storage systems. This interface provides for sparse block or object-based allocation, atomic multi-block updates, and a block discard interface to facilitate reclamation of unused storage. Finally, we present DFS, a file system designed specifically for next generation flash memory systems that takes advantage of our proposed storage interface. The result is a much-simplified file system implementation that runs under Linux. In both micro- and application benchmarks DFS shows consistent improvement over ext3 both in throughput and in CPU usage. For direct access DFS delivers as much as a 20% performance improvement in microbenchmarks. On an application level benchmark, DFS outperforms ext3 by 7 to 250% while requiring less CPU power.

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C Toler-Franklin preFPO
by Melissa Lawson 18 May '10

18 May '10

Corey Toler-Franklin will present her preFPO on Wednesday May 26 at 2:30PM in Room 402. The members of her committee are: Szymon Rusinkiewicz, advisor; Tom Funkhouser and Holly Rushmeier (Yale), readers; Adam Finkelstein and David Blei, nonreaders. Everyone is invited to attend her talk. Her abstract follow below. --------------------------------------------- Title: Matching, Visualizing and Archiving Cultural Heritage Artifacts Using Multi-Channel Images Abstract Recent advancements in low-cost acquisition technologies have made it more practical to acquire real-world datasets on a large scale. This has lead to a number of computer-based solutions for reassembling, archiving and visualizing cultural heritage artifacts. In this thesis, we combine aspects of these technologies in novel ways and introduce algorithms to improve upon their overall efficiency and robustness. First, we introduce a 2D acquisition system to address the challenge of acquiring higher resolution color and normal maps than those available with 3D scanning devices. Next, we incorporate our normal maps into a novel multi-cue matching system for reassembling small fragments of artifacts. We then present a non-photorealistic rendering pipeline for illustrating geometrically complex objects using images with multiple channels of information. Finally, we propose a data mining approach for visualizing historic artifacts from digital image collections. State-of-the-art 3D acquisition systems capture 3D geometry at archeological sites using affordable, off-the shelf scanners. Although multiple scans at varying viewpoints are required to assemble a complete model, robust registration and alignment algorithms, as well as new work-flow methodologies, significantly reduce the post-processing time. However, the color and normal maps obtained from these systems lack the subtle sub-millimeter details necessary for careful analysis, and high fidelity documentation. We introduce an algorithm that generates higher resolution normal maps and diffuse reflectance (true color texture), while minimizing acquisition time. Using shape from shading, we compute our normal maps from high resolution color scans of the object taken at four orientations on a 2D flat-bed scanner. A key contribution of our work is a novel calibration process to measure the observed brightness as a function of the surface normal. This calibration is important because the scanner's light is linear (rather than a point), and we cannot solve for the surface normal using the traditional formulation of the Lambertian lighting law. High resolution digital SLR cameras provide alternative solutions when objects are too large or fragile to place on a scanner. However, they require more control over the ambient light in the environment and additional manual effort to continually re-position a hand-held flash. They lack the high resolutions we obtain from the scanner. Several projects have been explored to leverage these newly acquired datasets for computer-assisted reassembly, and have proven successful in some domains. However, current matching algorithms do not perform well when artifacts have deteriorated over many years. One limitation is their reliance on previous acquisition methods that do not capture fine surface details that are important matching cues when features such as color, 2D contours or 3D geometry are no longer reliable. We introduce a set of feature descriptors that are based not only on color and shape, but also normal maps with a high data quality. Rather than rely exclusively on one form of data, we use machine-learning techniques to combine descriptors in a multi-cue matching framework. We have tested our system on three datasets of fresco fragments: Theran Frescos from the site of Akrotiri, Greece; Roman frescoes from Kerkrade in the Netherlands; and a Synthetic fresco created by conservators in a style similar to Akrotiri frescos. We demonstrate that multi-cue matching using different subsets of features leads to different tradeoffs between efficiency and effectiveness. We observe that individual feature performance varies from dataset to dataset and discuss the implications of feature importance for matching in this domain. Our results show good retrieval performance, significantly improving upon the match prediction rate of state-of the-art 3D matching algorithms. The Illustrative depictions found in biology or medical text-books are one possible method of archiving and distributing historic information. Using a datatype that stores both color and normals, RGBN images, we develop 2D analogs to 3D NPR rendering equations. Our approach extends signal processing tools such as scale-space analysis and segmentation for this new data type. We investigate stylize depiction techniques such as toon shading, line drawing and exaggerated shading. By incorporating some 3D information, we reveal fine details while maintaining the simplicity of a 2D implementation. Our results achieve levels of detail that are impractical to create with more conventional methods like manual 3D modeling or 3D scanning. Museums use digital cameras to archive their collections. When combined with the internet, digital collections create another powerful tool for disseminating information about history and culture. However, most systems permit only simplistic navigation through a fixed set of color or grayscale images. We propose a visualization technique that examines many images in the frequency domain to reveal information not easily apparent in conventional images, such as embedded watermarks, faded pigments or patterns in materials. In addition to RGBN images, our multi-channel image stacks combine many types of images including images with varied lighting and multiple wave lengths. We present algorithms to efficiently navigate a large search space, extract salient information across multiple images, and generate effective visualizations without manual adjustment of a large set of parameters. Unlike current techniques that are restricted to a single input image, we are able to reduce data loss and limit artifacts. We demonstrate these multi-channel image stacks using digital image collections provided by several institutions including the Smithsonian National Museum of the American Indian, the Library of Congress, and Cultural Heritage Imaging.

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N Heninger preFPO
by Melissa Lawson 18 May '10

18 May '10

Nadia Heninger will present her preFPO on Monday May 24 at 2PM in Room 402. The members of her committee are: Bernard Chazelle, advisor; Ed Felten and Henry Cohn (MSR New England), readers, Boaz Barak and Moses Charikar, nonreaders. Everyone is invited to attend her talk. Her abstract follows below. -------------------------------------------- Title: The mathematics of side-channel attacks Abstract: We will look at a collection of mathematical problems suggested by side-channel attacks against public key cryptosystems, and how the techniques inspired by this work relate to a variety of different applications. First, we discuss the cold boot attack, a side-channel attack against disk encryption systems that uses the phenomenon of DRAM remanence to recover encryption keys from a running computer. In the course of the attack, however, there may be errors introduced in the keys that the attacker obtains. It turns out that the structure of the key data in an AES key schedule can allow an attacker to more efficiently recover the private key in the presence of such errors. We extend this idea to a RSA private keys, and show how the structure of RSA private key data can allow an attacker to recover a key in the presence of random errors from 27% of the bits of the original key. Most previous work on RSA key recovery used the lattice-based techniques introduced by Coppersmith for finding low-degree roots of polynomials mod numbers of unknown factorization. We show how this approach can be extended from the integers to the ring of polynomials, and give a new proof via lattice basis reduction of Guruswami-Sudan list-decoding of Reed-Solomon codes. These theorems are in fact instances of a general approach, which we extend to show how to find small solutions to polynomials over ideals in number fields. On Mon, May 17, 2010 at 1:32 PM, Melissa Lawson <mml(a)cs.princeton.edu> wrote: > > thanks, Melissa > > >

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1:30pm talk today on network virtualization applied to health care, banking, and education
by Jennifer Rexford 17 May '10

17 May '10

Speaker: Dr. Sanjoy Paul, Infosys, Associate Vice President Title: Network Virtualization applied to the Network of a Communication Service Provider for Enabling Novel Services in Vertical Sectors Date/time: 1:30-2:30pm on Monday May 17 Location: CS 105 (small auditorium) Abstract: Communication technology has advanced significantly over the last decade enabling people to communicate anytime from anywhere using a multiplicity of devices. However, the power of this advancement in communication technology has hardly been leveraged in traditional services industry. Specifically, the vertical service providers, such as the Health Care industry, the Banking industry, the Education industry, and others who require network-based services to efficiently conduct their business reducing their operational expenses, and to provide novel value-added services to their customers generating additional revenue, have hardly been able to leverage the power of the network to their advantage. In the talk, I will describe several applications from the services industry that can be built on a platform (referred to as Network as a Service or NaaS platform) based on the concept of network virtualization and shows how various parties involved in providing the services are economically incentivized to make them feasible in real life. The NaaS platform enables Communication Service Providers (CSPs) to work collaboratively with Vertical Service Providers (VSPs) to offer novel services leveraging their existing network infrastructure through the techniques of network virtualization. This solution enables CSPs to generate new revenue without additional capital expenditure, and in addition, also enables VSPs to generate additional revenue via novel value-added service offerings to their customers without incurring any capital expenditure either. Thus, this model of offering services provides a win-win value proposition to both CSPs as well as to VSPs. NaaS Platform is being built at Infosys Technologies Limited. In course of my presentation, I’ll describe a high-level architecture of the platform and discuss how various functional blocks in the architecture are used synergistically to deliver a novel service called On Demand Health Care (ODHC). Bio: Sanjoy Paul (sanjoy_paul(a)infosys.com) is Associate Vice President, General Manager-Research and Head of Convergence Lab at Infosys Technologies Limited where he heads research and innovation in the field of Communications, Media and Entertainment. Prior to that, he was a Research Professor at WINLAB, Rutgers University, and Founder of RelevantAd Technologies Inc. Before that Sanjoy spent five years as the Director of Wireless Networking Research at Bell Labs, Lucent Technologies, and as the CTO of two start-up companies (Edgix and WhenU) based in New York. In a previous tenure at Bell Labs as a Distinguished Member of Technical Staff, Sanjoy was the chief architect of Lucent's IPWorX Caching and Content Distribution product line. Sanjoy has authored a book on Multicasting, published over 100 papers in International Journals and refereed Conference Proceedings, authored over 80 US patents (28 granted, 50+ pending), and is the co-recipient of 1997 William R. Bennett award from IEEE Communications Society for the best original paper in IEEE/ACM Transactions on Networking. He holds a Bachelor of Technology degree from IIT Kharagpur, India, an M.S and a Ph.D. degree from the University of Maryland, College Park, and an MBA from the Wharton Business School, University of Pennsylvania. Sanjoy is a Fellow of IEEE and a Member of the ACM.

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M Ali general exam
by Melissa Lawson 14 May '10

14 May '10

Muneeb Ali will present his research seminar/general exam on Thursday May 20 at 10AM in Room 402. The members of his committee are: Mike Freedman (advisor), Jennifer Rexford, and Larry Peterson. Everyone is invited to attend his talk and those faculty wishing to remain for the oral exam following are welcome to do so. His abstract and reading list follow below. --------------------------------------------------- Title: SWAM: A System for Wide-Area Migration -- Abstract -- The recent interest in cloud services is driven by the industrialization of the datacenter as a reliable provider of computing needs. Datacenters typically employ virtualization technologies (e.g., VMware ESXi and Citrix Xen) to better utilize and manage the physical resources. Virtual machines (VMs) can migrate on-the-fly, from one physical machine to another, to improve utilization, handle load spikes, and/or save power. However, these benefits are typically limited to resources within a single datacenter or, even worse, a single broadcast domain. Wide-area migration can enable resource sharing across physically apart locations, but efficiently migrating VMs over the wide-area is non-trivial. We identify the practical challenges in wide-area VM migration and propose a system, called SWAM, that aims to achieve efficient wide-area migration by reducing the time needed to transfer large (typically 8-10 GB) virtual disk images. SWAM leverages the fact that a VM disk image will have similarities in binary content (e.g., OS or program files) with other VMs running in a datacenter. Often VM images are "cloned" from generic base images and this often leads to high similarity between the binary content of different VMs. Further, a VM may migrate back and forth between the same servers and old versions of the disk image may be available on (or near) the target host. Our primary goal is to reduce the total migration time, especially the time in which the VM is non-responsive. SWAM aims to achieve this goal by a) enabling parallel download of content chunks from local peers within a datacenter, and b) providing mechanisms for quickly detecting and transferring disk image changes (deltas). We present results from a prototype implementation using VM images of Xen and KVM. --Papers-- [1] M. Harchol-Balter and A. B. Downey, "Exploiting process lifetime distributions for dynamic load balancing", ACM Trans. Comput. Syst. 15(3), pp 253-285, Aug. 1997 [2] A. Muthitacharoen, B. Chen, and D. Mazieres, "A low-bandwidth network file system", SOSP 2001, pp 174�187, Banff, Canada, Oct. 2001 [3] C. A. Waldspurger, "Memory resource management in VMware ESX server", OSDI 2002, pp 181�194, Boston, MA, Dec. 2002 [4] C. P. Sapuntzakis, R. Chandra, B. Pfaff, J. Chow, M. S. Lam, and M. Rosenblum, "Optimizing the migration of virtual computers", OSDI 2002, pp 377�390, Boston, MA, Dec. 2002 [5] I. Stoica, D. Adkins, S. Zhuang, S. Shenker, and S. Surana, "Internet indirection infrastructure", SIGCOMM 2002, pp 73-86, Pittsburgh, PA, Aug 2002 [6] P. Barham, B. Dragovic, K. Fraser, S. Hand, T. Harris, A. Ho, R. Neugebauer, I. Pratt, and A. War?eld, "Xen and the art of virtualization", SOSP 2003, pp 164�177, Bolton Landing, NY, Oct. 2003 [7] I. Stoica, R. Morris, D. Liben-Nowell, D. R. Karger, M. Frans Kaashoek, F. Dabek, and H. Balakrishnan, "Chord: a scalable peer-to-peer lookup protocol for internet applications", IEEE/ACM Trans. Netw. 11(1): 17-32 (2003) [8] C. Clark, K. Fraser, S. Hand, J. G. Hansen, E. Jul, C. Limpach, I. Pratt, and A. Warfield, "Live Migration of Virtual Machines", NSDI 2005, pp 273-286, Boston, MA, May 2005 [9] H. Pucha, D. G. Andersen, and M. Kaminsky, "Exploiting similarity for multi-source downloads using ?le handprints", NSDI 2007, Cambridge, MA, Apr. 2007 [10] D. Gupta, S. Lee, M. Vrable, S. Savage, A. Snoeren, G. Varghese, G. Voelker, and A. Vahdat, "Difference Engine: Harnessing memory redundancy in virtual machines", OSDI 2008, pp 309�322, San Diego, CA, Dec. 2008 --Textbook-- [11] L. L. Peterson and B. S. Davie, Computer Networks, Fourth Edition: a Systems Approach. 2007, Morgan Kaufmann Publishers Inc.

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J Farnham general exam
by Melissa Lawson 14 May '10

14 May '10

Jesse Farnham will present his research seminar/general exam on Thursday May 20 at 2PM in Room 402. The members of his committee are: Mona Singh (advisor), Andrea LaPaugh, and Tom Funkhouser. Everyone is invited to attend his talk and those faculty wishing to remain for the oral exam following are welcome to do so. His abstract and reading list follow below. --------------------------------------------- Abstract: "Interface Proteins: Investigating Modular Structure of Protein Interaction Networks" Organisms are able to adapt to and survive in different environments due partially to complex networks of interacting proteins within cells. These protein-protein interaction (PPI) networks can be represented as graphs, in which nodes indicate proteins and edges signify physical interactions between proteins. PPI networks are known to be "modular;" that is, a given protein is more likely to interact with similar proteins than with proteins involved in unrelated biological processes. PPI networks contain many "functional modules" of functionally-related, interacting proteins. This work investigates the means by which information flows between separate biological processes through protein interactions. We identify two protein classes: "Interface proteins", which mediate physical interactions between distinct functional modules, and "Insulated proteins," which interact primarily with members of their own functional module. Thus, interface proteins facilitate crosstalk between distinct processes, allowing information to flow through the interaction network. Furthermore, we show that functional modules tend to reuse the same interface proteins to interact with unrelated modules, rather than interacting with each unrelated module through a distinct set of interface proteins. Reading list: Textbooks: Mount, David. Bioinformatics: Sequence and Genome Analysis, 2nd Edition. Cormen, Leiserson, Rivest, and Stein. Introduction to Algorithms, 2nd Edition. (Chapters 22-26: Graph Algorithms) Papers: Banks et al. Organization of Physical Interactomes as Uncovered by Network Schemas. PLoS Computational Biology 4:10 (2008). Banks et al. NetGrep: Fast network schema searches in interactomes. Genome Biology 9:9 (2008). De Lichtenberg et al. Dynamic complex formation during the yeast cell cycle. Science 307 (2005). Fraser H. Modularity and evolutionary constraint on proteins. Nature Genetics 37:4 (2005). Hartwell et al. From molecular to modular cell biology. Nature 402 (1999). Komurov K, and White M. Revealing static and dynamic modular architecture of the eukaryotic protein interaction network. Molecular Systems Biology 3:110 (2007). Missiuro et al. Information Flow Analysis of Interactome Networks. PLoS Computational Biology 5:4 (2009). Taylor et al. Dynamic modularity in protein interaction networks predicts breast cancer outcome. Nature Biotechnology 27:2 (2009). Zotenko et al. Why do hubs in the yeast protein interaction network tend to be essential: Reexamining the connection between the network topology and essentiality. PLoS Computational Biology 4:8 (2008).

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A Venugopalan general exam
by Melissa Lawson 13 May '10

13 May '10

Anuradha Venugopalan will present her research seminar/general exam on Wednesday May 19 at 2PM in Room 402. The members of her committee are: Sanjeev Arora (advisor), Moses Charikar, and Bob Tarjan. Everyone is invited to attend her talk, and those faculty wishing to remain for the oral exam following are welcome to do so. Her abstract and reading list follow below. --------------------------------------------- Title: Investigating the 3-coloring and Vertex Cover problems Abstract: Mathematical programs and their hierarchies are currently the most commonly used approaches for approximating most combinatorial optimization problems. I shall talk about the existing SDP based algorithms for the coloring and Vertex Cover problems and show instances where these algorithms do not work well. In search of better algorithms for these problems, I shall make some observations about these instances. A recent work by Arora, Barak and Steurer offers better approximation guarantees than the SDP methods for some optimization problems including vertex cover. However, their algorithm uses time exponential in the threshold rank, that is, the number of 'large' eigenvalues of the graph. I shall show bounds on the threshold rank of the instances where the SDPs perform poorly and examine how the new algorithm performs on them. Reading List: -Unique Games on Expanding Constraint Graphs are Easy. : Arora Khot Kolla Steurer Tulsiani Vishnoi '08 -A 2^n^poly(\epsilon)-time Algorithm for Unique Games. : Arora Barak Steurer '10 -New Approximation Guarantee for Chromatic Number. : Arora Chlamtac Charikar '06 -Improved Approximation Guarantees Through Higher Levels of SDP Hierarchies. : Chlamtac Singh '08 -Optimal inapproximability results for max-cut and other 2-variable csps? : Khot Kindler Mossel O'Donnell '07 -SDP Integrality Gaps with Local l_1-Embeddability. : Khot Saket '09 -On semidefinite programming relaxations for graph coloring and vertex cover. : Charikar '02 -Integrality Gaps for Sherali-Adams Relaxations. : Charikar Makarychev Makarychev '09 -Towards strong nonapproximability results in the Lovasz-Schrijver hierarchy. : Alekhnovich Arora Tourlakis '05 -On the optimality of the random hyperplane rounding technique for max cut. : Feige Schechtman '02 -On the concentration of eigenvalues of random symmetric matrices. : Alon Krivelevich Vu '02 -A better approximation ratio for the Vertex Cover problem. : George Karakostas '05 -Computational Complexity: A modern approach. Chapters: 1-8 and the PCP chapters. : Arora Barak

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S Li general exam
by Melissa Lawson 13 May '10

13 May '10

Shi Li will present his research seminar/general exam on Wednesday May 19 at 10AM in Room 402. the members of his committee are: Moses Charikar (advisor), Sanjeev Arora, and Bob Tarjan. Everyone is invited to attend his talk and those faculty wishing to remain for the oral exam following are welcome to do so. His abstract and reading list follow below. ---------------------------------------------------- Title : Vertex Sparsifiers and Abstract Rounding Algorithms The notion of vertex sparsification (in particular cut-sparsification) is introduced by Moitra. It was shown that for any graph $G = (V, E)$ and a subset of $k$ terminals $K \subset V$, there is a polynomial time algorithm to construct a graph $H = (K, E_H)$ on just the terminal set so that simultaneously for all cuts $(A, K-A)$, the value of the minimum cut in $G$ separating $A$ from $K -A$ is approximately the same as the value of the corresponding cut in $H$. Then approximation algorithms can be run directly on $H$ as a proxy for running on $G$, yielding approximation guarantees independent of the size of the graph. In this work, we consider how well cuts in the sparsifier $H$ can approximate the minimum cuts in $G$, and whether algorithms that use such reductions need to incur a multiplicative penalty in the approximation guarantee depending on the quality of the sparsifier. We give a construction for $O(log k/\log \log k)$-quality cut sparsifers, which matches the best existential result. This is done by solving a mixed covering and matching linear programming derived from the 0-sum game used in the existential proof. We give the first super-constant lower bounds for how well a cut-sparsifier $H$ can simultaneously approximate all minimum cuts in $G$. We prove a lower bound of $\Omega(\log^{1/4} k)$ -- this is polynomially-related to the known upper bound of $O(\log k/\log \log k)$. This is an exponential improvement on the $\Omega(\log \log k)$ bound given in \cite{LM} which in fact was for a stronger vertex sparsification guarantee, and did not apply to cut sparsifiers. If we restrict the cut sparsifers to be from a linear combination of 0-extensions, we can show a better lower bound of $\Omega(\sqrt{log k})$. This restriction is quite reasonable since all known constructions, as well as exsitential proofs, are based on 0-extensions. Despite this negative result, we show that for many natural problems, we do not need to incur a multiplicative penalty for our reduction. Roughly speaking, we show that many graph partitioning problems can be reduced to correspodent problems restricted to trees, at the price of $O(\log k)$ in the approximation ratio. For many problems, this saves an $O(\log k/\log\log k)$ multiplicative factor in the approximation ratio, compared to the algorithm where we first sparsify the graph and then solve the problem on the smaller graph. This result helps to explain the intrinsic robustness of graph partitioning problems - i.e. why does $O(\log k)$ always seem to be the right answer for the approximation ratio? Papers : [AFH+ 04] Aaron Archer, Jittat Fakcharoenphol, Chris Harrelson, Robert Krauthgamer, Kunal Talwar, and Eva Tardos. Approximate classification via earthmover metrics. In SODA '04: Proceedings of the fifteenth annual ACM-SIAM symposium on Discrete algorithms, pages 1079-1087, Philadelphia, PA, USA, 2004. Society for Industrial and Applied Mathematics. [CKR01] Gruia Calinescu, Howard Karloff, and Yuval Rabani. Approximation algorithms for the 0-extension problem. In SODA '01: Proceedings of the twelfth annual ACM-SIAM symposium on Discrete algorithms, pages 8-16, Philadelphia, PA, USA, 2001. Society for Industrial and Applied Mathematics. [FHRT03] Jittat Fakcharoenphol, Chris Harrelson, Satish Rao, and Kunal Talwar. An improved approximation algorithm for the 0-extension problem. In SODA '03: Proceedings of the fourteenth annual ACM-SIAM symposium on Discrete algorithms, pages 257-265, Philadelphia, PA, USA, 2003. Society for Industrial and Applied Mathematics. [KKL88] J. Kahn, G. Kalai, and N. Linial. The influence of variables on boolean functions. In SFCS '88: Proceedings of the 29th Annual Symposium on Foundations of Computer Science, pages 68-80, Washington, DC, USA, 1988. IEEE Computer Society. [Moi09] Ankur Moitra. Approximation algorithms for multicommodity-type problems with guarantees independent of the graph size. In FOCS, pages 3-12, 2009. [FRT03] Fakcharoenphol, Jittat, Rao, Satish, and Talwar, Kunal: A tight bound on approximating arbitrary metrics by tree metrics, STOC '03, ACM, 448-455, 2003 [AHK05] Arora, Sanjeev, Hazan, Elad, and Kale, Satyen: The multiplicative weights update method: a meta algorithm and applications, 2005 [You01] Young, Neal E.: Sequential and Parallel Algorithms for Mixed Packing and Covering, In 42nd Annual IEEE Symposium on Foundations of Computer Science, 538-546, 2001 Books : Computational complexity, a modern approach, by Sanjeev Arora and Boaz Barak, 2009. Chapters : 0 ~ 9, 11, 14, 19, 22 Appromixation Algorithms, by Vijay V. Vazirani, 2001 Chapters : 4, 11, 12, 15, 18 ~ 21, 26

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Xiaojuan Ma FPO
by Melissa Lawson 13 May '10

13 May '10

Xiaojuan Ma will present her FPO on Thursday May 20 at 11AM in Room 302. The members of her committee are: Perry Cook, advisor; Christiane Fellbaum and Marilyn Tremaine (Rutgers), readers; Szymon Rusinkiewicz and Ken Steiglitz, nonreaders. A copy of her thesis, "Communication Beyond Words: Multimedia Approaches to Bridging Language Disabilities and Barriers", is on display in room 310. Everyone is invited to attend her talk.

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