- talks - lists.cs.princeton.edu

Rajesh Ranganath will present his FPO, "Black Box Variational Inference: Scalable, Generic Bayesian Computation and its Applications" on Friday, 10/6/2017 at 11am in CS 105.
by Nicki Gotsis 02 Oct '17

02 Oct '17

Rajesh Ranganath will present his FPO, "Black Box Variational Inference: Scalable, Generic Bayesian Computation and its Applications" on Friday, 10/6/2017 at 11:00 in CS 105. The members of his committee are as follows: David Blei (Adviser); Examiners: Sanjeev Arora, Barbara Engelhardt, and David Blei; Non Examiners: David Blei and Peter Orbanz (Columbia University, Department of Statistics) A copy of his thesis, is available in Room 310. Everyone is invited to attend his talk. The talk abstract follows below. Probabilistic generative models are robust to noise, uncover unseen patterns, and make predictions about the future. These models have been used successfully to solve problems in neuroscience, astrophysics, genetics, and medicine. The main computational challenge is computing the hidden structure given the data—posterior inference. For most models of interest, computing the posterior distribution requires approximations like variational inference. Variational inference transforms posterior inference into optimization. Classically, this optimization problem was feasible to deploy in only a small fraction of models. This thesis develops black box variational inference. Black box variational inference is a variational inference algorithm that is easy to deploy on a broad class of models and has already found use in models for neuroscience and health care. It makes new kinds of models possible, ones that were too unruly for previous inference methods. One set of models we develop is deep exponential families. Deep exponential families uncover new kinds of hidden pattens while being predictive of future data. Many existing models are deep exponential families. Black box variational inference makes it possible for us to quickly study a broad range of deep exponential families with minimal added eort for each new type of deep exponential family. The ideas around black box variational inference also facilitate new kinds of variational methods. First, we develop hierarchical variational models. Hierarchical variational models improve the approximation quality of variational inference by building higher-fidelity approximations from coarser ones. We show that they help with inference in deep exponential families. Second, we introduce operator variational inference. Operator variational inference delves into the possible distance measures that can be used for the variational optimization problem. We show that this formulation categorizes various variational inference methods and enables variational approximations without tractable densities. By developing black box variational inference, we have opened doors to new models, better posterior approximations, and new varieties of variational inference algorithms.

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Katie Anna Wolf will present her FPO, "Methods for Personalized Design of Data Sonification" on Wednesday, 8/30/2017 at 10am in CS 402
by Nicki Gotsis 23 Aug '17

23 Aug '17

Katie Anna Wolf will present her FPO, "Methods for Personalized Design of Data Sonification" on Wednesday, 8/30/2017 at 10:00am in CS 402. The members of her committee are: Advisers: Adam Finkelstein and Rebecca Fiebrink (Goldsmiths, University of London); Readers: Michael Nees (Lafayette College), Adam Finkelstein, and Rebecca Fiebrink (Goldsmiths, University of London); Examiners: Adam Finkelstein, Marshini Chetty, and Daniel Trueman (Music). A copy of her thesis is available in Room 310. Everyone is invited to attend her talk. Attached is the talk abstract.

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Stephen Beard will present his Pre FPO "Containment Architecture with Verified Output: A Model for Practical Trust in Real Systems" in CS 302 on Monday, August 14th at 1pm.
by Nicki Gotsis 08 Aug '17

08 Aug '17

Stephen Beard will present his Pre FPO "Containment Architecture with Verified Output: A Model for Practical Trust in Real Systems" in CS 302 on Monday, August 14th at 1pm. The members of his committee are as follows: David August (advisor) Andrew Appel (reader) Jothy Rosenberg (Dover Microsystems) (reader) Aarti Gupta (non-reader) Arvind Narayanan (non-reader) Everyone is invited to attend his talk. The talk abstract follows below: Abstract: All layers of today’s computing systems, from hardware to software, are vulnerable to attack. Market and economic pressure generally result in companies focusing on performance and features, leaving security and correctness as post deployment concerns. Thus, systems must frequently be patched or augmented after deployment to fix security vulnerabilities. While this non-virtuous exploit-patch-exploit cycle is not the most secure, it is practical enough for companies to use. Formal methods in both software and hardware can give true guarantees as to the security they provide. Ideally, modern systems would be comprised of entirely formally verified and secure components. Unfortunately, such methods have not seen widespread adoption for a number of reasons, such as difficulty in scaling, lack of tools, and high skill requirements. Additionally, the economics involved in securing and replacing every component in all systems, both new and currently deployed, are a major factor in clean slate solutions being unrealistic. Thus, a practical solution should rely on a few, simple components and should be adoptable incrementally. As the first implementation of the Containment Architecture with Verified Output (CAVO) model developed at Princeton, TrustGuard showed how a simple trusted Sentry could protect against malicious or buggy hardware components to ensure integrity of external communications. This was accomplished by ensuring the correct execution of signed software, with support from a modified CPU and system architecture. However, TrustGuard’s practicality was limited due to its reliance on modified host hardware and its requirement to trust entire application stacks, including the operating system. The work presented in this dissertation seeks to make the CAVO model a practical solution for ensuring the integrity of data communicated externally in an untrusted commodity system. This work extends CAVO in two ways. The first extension is to make the Sentry compatible with a wide range of devices without requiring hardware modifications to the host system, thus increasing its flexibility and ease of integration into existing environments. The second extension is to give developers the option to use trusted code to verify the execution of untrusted code, thus reducing the size of the trusted code base. This is similar to the way that the small, trusted Sentry can ensure correctness of execution of a large amount of complex, untrusted hardware.

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Danny Huang on Cryptocurrencies, July 25 @ 12:30p
by Nick Feamster 25 Jul '17

25 Jul '17

All, Danny Huang will visit us from UCSD on July 25. He’ll give a talk on Cryptocurrencies (abstract below). If you’d like to chat with him, please sign up here: https://goo.gl/nhni3p -Nick ————— Date: July 25, 2017 Time: 12:30 p Place: Sherrerd Hall 306 (Conference Room) Title: Crypto-currencies: New opportunities for criminals, investors, and human-trafficking fighters. Abstract: When Satoshi Nakamoto designed Bitcoin, he had intended it as an “electronic cash system.” However, it is difficult to treat Bitcoin as a form of cash or currency, especially given its price volatility. Still, Bitcoin, as well as thousands of other similar crypto-currencies, allows for the exchange of value in a decentralized and partially anonymous manner. These properties have created opportunities for novel use cases, far beyond the original design goals of Satoshi Nakamoto. As I will discuss in the talk, these use cases span from being unethical to nobel, and from profit-driven to promoting social justice. In particular, three classes of users will be our focus today: (1) criminals who monetize stolen CPU cycles and files with Bitcoin; (2) investors who speculate in crypto-currencies; and (3) human-trafficking fighters who take advantage of a timing side channel in Bitcoin. ——— About the speaker: Danny Y. Huang is a PhD student at UC San Diego. He is generally interested in the economics of security/privacy. He is graduating in August. Details: https://sysnet.ucsd.edu/~dhuang

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Rafael Mendes de Oliveira will present his FPO, "Polynomial Identity Testing: Derandomization Results and Applications to Algebraic Computation" on Friday, July 21, 2017 at 1pm in Friend Center 401.
by Nicki Gotsis 18 Jul '17

18 Jul '17

Rafael Mendes de Oliveira will present his FPO, "Polynomial Identity Testing: Derandomization Results and Applications to Algebraic Computation" on Friday, July 21, 2017 at 1pm in Friend Center 401. The members of his committee are as follows: Nonreaders: Zeev Dvir (adviser), Gillat Kol, Mark Braverman, and Ran Raz; Readers: Zeev Dvir (adviser) and Gillat Kol A copy of his thesis is available in Room 310. Everyone is invited to attend his talk. The talk abstract follows below: The polynomial identity testing problem (PIT) is a fundamental problem in Complexity Theory, as it is one of the few problems for which there exists a polynomial time randomized algorithm, but no deterministic sub-exponential time algorithm has been discovered. Moreover, many fundamental algorithmic problems can be reduced to particular instances of the PIT problem, which makes its derandomization even more interesting, as it may yield fast deterministic parallel algorithms for such algorithmic problems. The aim of this thesis is to provide new results and new approaches to solving the PIT problem. In the first part of this thesis (Chapter 3), we focus on the PIT problem in the commutative setting. In the first half of this chapter, we provide new deterministic algorithms for multiliinear circuits of low depth and for regular multilinear formulas. In the second half we provide a new application of PIT to the problem of testing equivalences of two polynomials under shifts of the inputs. In the second part of this thesis (Chapter 4), we focus on structural results for factors of commutative polynomials whose degree in each variable is bounded by a constant. We prove that if such a polynomial can be computed by a low-depth circuit of polynomial size, then its factors can also be computed by low-depth circuits of polynomial size. We hope that such structural results provide additional insights in tackling the PIT problem for bounded depth circuits. In the final part of this thesis (Chapter 5), we introduce the setting of non-commutative computation with inversion gates and study the rational identity testing (RIT) problem. We prove the first deterministic polynomial time algorithm for the RIT problem for general non-commutative formulas. Our proof goes via a reduction to the operator scaling problem, which we also discuss in this chapter, and is an analytic approach to the PIT problem, unlike all previous approaches, which are of a purely algebraic nature.

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Aaron Blankstein will present his FPO, "Exploiting the Structure of Modern Web Applications" on Wednesday, 6/28/2017 at 11:00am in CS 402.
by Nicki Gotsis 21 Jun '17

21 Jun '17

Aaron Blankstein will present his FPO, "Exploiting the Structure of Modern Web Applications" on Wednesday, 6/28/2017 at 11:00am in CS 402. The members of his committee are as follows: Readers: Jennifer Rexford and Nick Feamster; Nonreaders: Robert Tarjan, Kyle Jamieson, and Michael Freedman (Adviser) A copy of the thesis is available in CS 310. All are welcome to attend. Abstract: In this thesis, I show how, in many respects, modern web applications are built with implicit structure, such that several classic problems in computer systems can be tackled in new ways, allowing today’s applications to readily reap security or performance benefits. I apply this to two separate contexts. In the first, I look at the problems of providing some automatic security to web applications by partitioning the server-side code of the application, isolating those partitions, learning access control policies for those partitions, and extending this isolation to front-end code with JavaScript sandboxing. In the second, I look at how modern web applications interact with application caches, and develop a family of cache eviction policies tailored to these needs by focusing on prioritizing individual items to capture how item request frequencies, associated costs, and expiration times affect cache performance.

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Fwd: Friday 6/2 : Erez Lieberman-Aiden “A 3D Code in the Human Genome”
by Nicole E. Wagenblast 25 May '17

25 May '17

Dear colleagues, Erez Lieberman-Aiden, inventor of the Hi-C method for three-dimensional DNA sequencing, will be visiting Princeton on June 2nd. He will be giving a talk in Icahn 101 at 11am on Friday, June 2nd on the development of Hi-C and its applications, including the construction of 3D maps in multiple cell types and the correlation of these loops with gene activation. Erez also has time in his schedule for some individual meetings throughout the day. If you are interested in meeting with him, please email Dawn Capizzi ( dcapizzi(a)exchange.Princeton.EDU ). Thanks, and hope to see you there! All the best, Sarah Kocher Save

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Friday at 11a - Hijacking Bitcoin: Routing Attacks on Cryptocurrencies
by Nick Feamster 24 May '17

24 May '17

Please let me know if you’d be interested in meeting Maria on Friday afternoon. Thanks! -Nick ————— Hijacking Bitcoin: Routing Attacks on Cryptocurrencies Maria Apostolaki, ETH Zürich 11a, Sherrerd Hall 306 Abstract As the most successful cryptocurrency to date, Bitcoin constitutes a target of choice for attackers. In this talk, we will look at the impact and practicality of Internet routing attacks on the cryptocurrency. We will show that the efficiency of routing manipulation and the significant centralization of Bitcoin in terms of mining and routing make two large-scale routing attacks possible today. The first attack consists in partitioning the Bitcoin network into two disjoint components of almost equal mining power by hijacking few (<100) BGP prefixes. The second attack consists in considerably delaying block propagation by interfering with few key Bitcoin messages in a stealth way. The potential damage to Bitcoin is worrying. Among others, such attacks could reduce miners’ revenue and render the network much more susceptible to double spending and selfish mining. Bio Maria Apostolaki is a second year PhD student in the Networked Systems Group at ETH Zürich, advised by Prof. Laurent Vanbever. Her research focus on Internet routing and its implication on performance and security. Prior to joining ETH, Maria earned her diploma in Electrical and Computer Engineering at the National Technical University of Athens, Greece.

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Abhinav Narain (Georgia Institute of Technology) will present "Near-Field Deniable Communication" on Wednesday, May 24, 2017 in the CITP conference room, 3rd Fl, Sherrerd Hall at 11am
by Nicki Gotsis 24 May '17

24 May '17

Abhinav Narain (Georgia Institute of Technology) will present his defense talk "Near-Field Deniable Communication" on Wednesday, May 24, 2017 in the CITP conference room, 3rd Fl, Sherrerd Hall at 11am (Webcast : http://bit.ly/2qFJXx6) Title: Near-Field Deniable Communication ----- Abhinav Narain School of Computer Science College of Computing Georgia Institute of Technology Committee --------- Prof. Nick Feamster (Adviser, School of Computer Science, Princeton University) Prof. Mostafa Ammar, (School of Computer Science, Georgia Institute of Technology) Prof. Taesoo Kim, (School of Computer Science, Georgia Institute of Technology) Prof. Alex Snoeren, (Dept. of Computer Science, University of California, San Diego) Date: Wednesday, May 24, 2017 Time: 11 am to 1 pm EST Location: CITP conference room, third floor, Sherrerd Hall, Princeton University Webcast : http://bit.ly/2qFJXx6 There is constant surveillance by employers, corporations, and governments. Long people have wanted to keep their communication private but With increasing interest of state and private organizations and corporations in the daily lives of people, such a discussion is on the rise. This dissertation develops techniques and systems that empower users to evade such intentions of adversaries. Our work builds from the observation to leverage randomness in physical nature of the world everywhere, specifically using technologies such as wireless and power-lines networks in urban settings. This thesis is divided into two parts. First part, we develop Denali, which allows deniable communication in wireless 802.11 networks. Denali achieves this by leveraging the weakness of wireless networks which has packet corruption due to its ubiquitous nature of being broadcast medium. This is the first such system which uses off-the-shelf commodity hardware to users. In the second part, we explore a different network primarily used for powering devices in building infrastructure -- power-line network. We build Power-line Whisperer, a physical layer covert communication channel. Power-line Whisperer is the first of its kind of system to make it easier for people to to do deniable communication on power-line networks. Both these systems allow the users to do point-to-point communication and defend against powerful adversaries who might be interested in snooping on the message exchange for malicious reasons.

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Yonatan Naaman will present his Pre FPO "Hardness from Dense Subgraph Conjectures" on Thursday, May 25th, 2017 in CS 402 at 6pm.
by Nicki Gotsis 22 May '17

22 May '17

Yonatan Naaman will present his Pre FPO "Hardness from Dense Subgraph Conjectures" on Thursday, May 25th, 2017 in CS 402 at 6pm. Everyone is invited to attend his talk. The members of his committee are as follows: Moses Charikar (adviser) Sanjeev Arora (reader) Anthony Wirth (U. Melbourne) (reader) Mark Braverman (non-reader) Matt Weinberg (non-reader) Title: "Hardness from Dense Subgraph Conjectures". Abstract: Karp's seminal paper on NP-Completeness provided computer scientists with a toolkit for showing computational hardness, conditioned on a complexity theoretic conjecture, for a wide variety of optimization problems. However, the techniques used in his paper say little about the hardness of approximating the optimal objective values of these problems. While researchers have since managed to find tight bounds on the approximability of some of these NP-hard problems, many others still have embarrassingly large gaps between their known upper and lower limits of approximation. To fill in these gaps, researchers have posed myriad new complexity theoretic conjectures that entail stronger lower bounds at the expense of more demanding hypotheticals. One class of conjectures focuses on the approximability of the Densest k-Subgraph (DkS) problem. Namely, the conjectured hardness of both adversarial and average-case variants of DkS has been shown to imply stronger hardness for many problems for which good approximation algorithms have proven elusive. In this thesis, we describe techniques for proving stronger hardness results conditioned on both the known and the conjectured hardness of Densest k-Subgraph. We show how previous results on DkS imply stronger lower bounds on ``MinRep-hard'' problems, as well as a simple technique for converting many proofs of MinRep-hardness into proofs of DkS-hardness. Using this and other techniques, we show DkS hardness for problems such as Minimum Colored Cut, Target Set Selection, Minimum Monotone Satisfying Assignment (MMSA), Network Flow Interdiction, Power Dominating Set, Densest k-Common Subgraph, among others. In the case of Target Set Selection and MMSA, we show how to obtain substantially stronger lower bounds by exploiting the self-similar structure of instances conjectured to be average-case-hard. We also provide improved approximation algorithms for some of the discussed problems.

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