Microsoft Research Lectures
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Thu, 23 Jul 2015 10:37:17 GMT
Thu, 23 Jul 2015 10:37:17 GMT

Approximating ATSP by Relaxing Connectivity
[Speaker: Ola Svensson] The standard LP relaxation of the asymmetric traveling salesman problem has been conjectured to have a constant integrality gap in the metric case. We prove this conjecture when restricted to shortest path metrics of nodeweighted digraphs. Our arguments are constructive and give a constant factor approximation algorithm for these metrics. We remark that the considered case is more general than the directed analog of the special case of the symmetric traveling salesman problem for which there were recent improvements on Christofides' algorithm. The main idea of our approach is to first consider an easier problem obtained by relaxing the general connectivity requirements into local connectivity conditions. For this relaxed problem, it is quite easy to give an algorithm with a guarantee of 3 on nodeweighted shortest path metrics. More surprisingly, we then show that any algorithm (irrespective of the metric) for the relaxed problem can be turned into an algorithm for the asymmetric traveling salesman problem by only losing a small constant factor in the performance guarantee. This leaves open the intriguing task of designing a "good" algorithm for the relaxed problem on general metrics.
http://research.microsoft.com/apps/video/default.aspx?id=251386
Ola Svensson
Science and Technology
Wed, 22 Jul 2015 21:00:00 GMT

The State of Techniques for Solving Large ImperfectInformation Games, Including Poker
[Speaker: Tuomas Sandholm] The ability to computationally solve imperfectinformation games has a myriad of future applications ranging from auctions, negotiations, and (cyber)security settings to medical domains. A dramatic scalability leap has occurred in the capability to solve such games over the last nine years, fueled in large part by the Annual Computer Poker Competition. I will discuss the key, domainindependent, techniques that enabled this leap, including automated abstraction techniques and approaches for mitigating the issues that they raise, new equilibriumfinding algorithms, safe opponent exploitation methods, techniques that use qualitative knowledge as an extra input, and endgame solving techniques. I will also include new results on 1) developing the world’s best HeadsUp NoLimit Texas Hold'em poker program, 2) theory that enables abstraction that gives solution quality guarantees, 3) techniques for hot starting equilibrium finding, 4) simultaneous abstraction and equilibrium finding, and 5) theory that improves gradientbased equilibrium finding. I will also cover the Brains vs AI competition that I recently organized where our AI, Claudico, challenged four of the top10 human pros in HeadsUp NoLimit Texas Hold'em for 80,000 hands. (The talk covers joint work with many coauthors, mostly Noam Brown, Sam Ganzfried, and Christian Kroer.
http://research.microsoft.com/apps/video/default.aspx?id=251387
Tuomas Sandholm
Science and Technology
Wed, 22 Jul 2015 17:30:00 GMT

FixedEnergy Harmonic Functions
[Speaker: Rick Kenyon] We study the map from conductances to edge energies for harmonic functions on graphs with Dirichlet boundary conditions. We prove that for any compatible acyclic orientation and choice of energies there is a unique choice of conductances such that the associated harmonic function realizes those orientations and energies. For planar graphs there is a harmonic conjugate function; together these form the real and imaginary parts of a "fixed energy" analytic function. There is a geometric realization of the graph as a tiling of a plane region with fixedarea rectanges ("floorplans"). This is joint work with Aaron Abrams.
http://research.microsoft.com/apps/video/default.aspx?id=251080
Rick Kenyon
Science and Technology
Mon, 20 Jul 2015 22:30:00 GMT

A Faster Cutting Plane Method and its Implications for Combinatorial and Convex Optimization
[Speaker: YinTat Lee] In this talk, I will present a new algorithm for finding a point in a convex set given a separation oracle. In particular, given a separation oracle for a convex set K in Rn that is contained in a box of radius R, I will show how to either compute a point in K or prove that K does not contain a ball of radius eps using an expected O(n log(nR/eps)) evaluations of the oracle and additional time O~(n3). This improves upon the O~(n3.373) additional time of the previous fastest algorithm achieved over 25 years ago by Vaidya. As an example, I will show how to use it to obtain a faster algorithm for the following problems: 1. Submodular Function Minimization 2. Submodular Flow 3. Matroid Intersection 4. Semidefinite Programming
http://research.microsoft.com/apps/video/default.aspx?id=250722
YinTat Lee
Science and Technology
Thu, 16 Jul 2015 22:30:00 GMT

Privacy Protection, Personalized Medicine and Genetic Testing
[Speaker: Catherine Tucker] Personalized medicine  where the treatment is as individual as the patient  has been discussed as the future of medicine. But the use of a person's genetic code to personalize treatment raises new and difficult privacy concerns. Professor Tucker will discuss current approaches to regulating genetic privacy at the state level and the degree of success such approaches have had at promoting the spread of personalized medicine and testing.
http://research.microsoft.com/apps/video/default.aspx?id=251055
Catherine Tucker
Science and Technology
Wed, 15 Jul 2015 20:00:00 GMT

The First Order World of GaltonWatson Trees
[Speaker: Joel Spencer] Consider the classic GaltonWatson tree T=Tc in which each node, independently, has Poisson mean c children. The probability f(c) that Tc is infinite is continuous, but it is not differentiable at the critical point c=1. Let, for example, g(c) be the probability that some node has precisely one child. This g(c) has derivatives of all orders and, indeed, is real analytic. We show that for a wide variety of properties, called First Order properties, the probability h(c) will be real analytic and, furthermore, can be found as the unique fixed point of a contraction Ψ on a compact set D. We introduce a notion of a property being "rapidly determined" and its effect on the corresponding probability function.
http://research.microsoft.com/apps/video/default.aspx?id=250707
Joel Spencer
Science and Technology
Tue, 14 Jul 2015 22:30:00 GMT

Altering Human Perception and Behavior through Immersive Virtual Reality
[Speaker: Mar Gonzalez] Several studies have shown that people inside Immersive Virtual Reality (VR) behave realistically when presented with complex situations. As a result a new generation of social and behavioral scientists are turning into VR to design experiments including moral dilemmas. Furthermore, using realtime motion tracking and HeadMounted Displays it is possible to give participants an egocentric view of a colocated virtual body. Through multisensory stimulation, healthy humans can experience full body ownership and agency illusions over an avatar – as if their real body was perceptually substituted by a virtual one. This allows for manipulations beyond what would be possible in reality, i.e. altering the race, gender or body parts to explore the human perception thresholds. The effects and traces of such body substitution can be measured using subjective reporting, behavioral and objective physiological measures. Part of my research has focused on uncovering the underlying neurological mechanisms that trigger ownership, agency, and overall realistic responses inside VR. These findings are now transcending to the consumer arena with the new era of VR applications and devices called to radically change the paradigms of human computer interaction.
http://research.microsoft.com/apps/video/default.aspx?id=251081
Mar Gonzalez
Science and Technology
Tue, 14 Jul 2015 17:30:00 GMT

Capturing and simulating the interaction of light with the world around us.
[Speaker: Wenzel Jakob] Driven by the increasing demand for photorealistic computergenerated images, graphics is currently undergoing a substantial transformation to physicsbased approaches which carefully process visual information characterizing both object shape and the interaction of light and matter. Progress on all fronts of this transition – acquisition, physical models and simulation techniques – has been steady but mostly independent from another. When combined, the resulting methods are in many cases impracticably slow and require unrealistic workarounds to process even simple everyday input. My research lies at the interface of these research fields; my goal is to break down the barriers between acquisition, simulation techniques and the underlying physical models, and to use the resulting insights to develop realistic methods that remain efficient over a wide range of inputs. I will cover three areas of recent work: the first involves volumetric modeling approaches to create realistic images of woven and knitted cloth. Next, I will discuss reflectance models for glitter/sparkle effects and arbitrarily layered materials that are specially designed to allow for efficient simulations. In the last part of the talk, I will give an overview of Manifold Exploration, a Markov Chain Monte Carlo technique that is able to reason about the geometric structure of light paths in high dimensional configuration spaces defined by the underlying physical models, and which uses this information to accelerate computation of rendered images and animation sequences.
http://research.microsoft.com/apps/video/default.aspx?id=250968
Wenzel Jakob
Science and Technology
Mon, 13 Jul 2015 10:00:00 GMT

Advances in Quantum Algorithms & Devices: Quantum versus classical annealing
[Speaker: Matthias Troyer] I will discuss several recent findings about the computational power of quantum annealing, either on quantum hardware or as “simulated quantum annealing” by quantum Monte Carlo (QMC) simulations on a classical computer. The failure to so far observe quantum speedup on DWave Two is in contradiction to previous QMC results that indicated quantum speedup for spin glasses. This apparent contradiction can be resolved by taking the continuous time limit in the QMC simulations. We find that continuous time QMC simulations agree with the behavior of dWave and show no speedup for 2D spin glasses. However, QMC simulations with large time steps gain further advantage: they “cheat” by ignoring what happens during a (large) time step, and can thus outperform both simulated quantum annealers and classical annealers. While this is good news for the development of quantum inspired classical optimization algorithms, it further raises the bar for quantum annealers. A second topic that I will discuss is how to optimally run a quantum annealer. Investigating the behavior of the tails of the distribution of runtimes for very hard instances we find that adiabatically slow annealing is far from optimal. On the contrary, many repeated relatively fast annealing runs can be orders of magnitude faster for hard problems. The intuitive explanation is that hard instances, which are stuck in the “wrong” minimum can be solved faster by perturbing them. Finally, I will discuss the prospects of quantum annealing outperforming classical annealing on hard optimization problems.
http://research.microsoft.com/apps/video/default.aspx?id=250888
Matthias Troyer
Science and Technology
Fri, 10 Jul 2015 22:50:00 GMT

Advances in Quantum Algorithms and Devices: A quantum algorithm for computing the unit group of an arbitrary degree number field
http://research.microsoft.com/apps/video/default.aspx?id=250889
Sean Hallgren
Science and Technology
Fri, 10 Jul 2015 22:10:00 GMT

Advances in Quantum Algorithms & Devices: Positionbased cryptography
http://research.microsoft.com/apps/video/default.aspx?id=250891
Harry Buhrman
Science and Technology
Fri, 10 Jul 2015 21:00:00 GMT

Advances in Quantum Algorithms & Devices: Exact synthesis for qubit unitaries
[Speaker: Jon Yard] The SolovayKitaev Theorem shows that any finite subset of SU(2) generating a dense subgroup can be used to epsilonapproximate an arbitrary qubit unitary using a quantum circuit of length O(polylog(1/epsilon)). Recent advances in quantum compiling achieved dramatically improved approximations to arbitrary unitaries with O(log(1/epsilon))length circuits over special qubit gate sets. A necessary component of such compiling tasks involves solving the “exact synthesis problem” for the given gate set: Given a unitary that can be expressed as a circuit over the elementary gates, the exact synthesis problem is to find the shortest circuit implementing that unitary. In this talk, I will present joint work with Vadym Kliuchnikov, showing how sophisticated mathematical tools from the theory of quaternion orders can be put to work to solve this problem for a very broad class of gate sets including Clifford+T, Vbasis and braiding of nonabelian anyons in SU(2) ChernSimons theory at finite level.
http://research.microsoft.com/apps/video/default.aspx?id=250893
Jon Yard
Science and Technology
Fri, 10 Jul 2015 20:20:00 GMT

Advances in Quantum Algorithms & Devices: Quantum Monte Carlo versus Quantum Adiabatic Optimization
[Speaker: Wim van Dam] How many queries are needed to determine a polynomial F(X)? We look at this question when F(X) is defined over a finite field GF(q) and has degree d, such that d+1 queries are obviously sufficient. Shamir's Secret Sharing protocol is based on the result that d+1 classical queries are also needed as no interpolation is possible based on only d values of F. Here we look at how many quantum queries are sufficient to perform the same task. Earlier work by [Kane & Kutin 2009] and [Meyer & Pommersheim 2010] proved that at least d/2+1/2 quantum queries are needed, while [Boneh and Zhandry 2012] showed that d quantum queries are sufficient. In this talk we will describe a quantum algorithm that uses only d/2+1/2 queries and that has a constant success probability. Our algorithm relies on the analysis of the classical Moment Problem defined over finite fields. (Joint work with Andrew Childs)
http://research.microsoft.com/apps/video/default.aspx?id=250879
Wim van Dam
Science and Technology
Fri, 10 Jul 2015 18:20:00 GMT

Advances in Quantum Algorithms and Devices: A Quantum Approximate Optimization Algorithm
http://research.microsoft.com/apps/video/default.aspx?id=251083
Eddie Farhi
Science and Technology
Fri, 10 Jul 2015 17:40:00 GMT

Computational Imaging and Illumination for 3D Acquisition: Research at the NU Comp Photo Lab
[Speaker: Oliver Cossairt] Computational imaging and illumination plays a central role in many modern threedimensional imaging techniques. In this talk, I will provide an overview of several 3D imaging technologies pioneered by the NU Comp Photo Lab, highlighting 3 main research projects. First, I will introduce a novel structured light technique called Motion Contrast 3D scanning (MC3D) that maximizes bandwidth and light source power to avoid performance tradeoffs in structured light 3D acquisition. The technique allows 3D laser scanning resolution with singleshot speed, even in the presence of strong ambient illumination, significant interreflections, and highly reflective surfaces. Next, I will present research on Incoherent Holography, which enables 3D digital refocusing by engineering the camera's Point Spread Function (PSF). The technique can be used to capture a hologram without illuminating the scene with a coherent laser, making it possible to acquire holograms even for passively illuminated scenes. Finally, I will introduce our work using photometric stereo to measure the surface shape of several of Paul Gauguin's prints and drawings housed at the Art Institute of Chicago. In this work we characterize surface topology to better understand the artists production methods, helping to resolve longstanding art historical questions about the evolution of Gauguin's printing techniques.
http://research.microsoft.com/apps/video/default.aspx?id=250196
Oliver Cossairt
Science and Technology
Fri, 10 Jul 2015 17:30:00 GMT

Advances in Quantum Algorithms and Devices: Bounding Quantum Gate Error Rate Based on Reported Average Fidelity
[Speaker: Barry Sanders] Remarkable experimental advances in quantum computing are exemplified by recent announcements of impressive gate fidelities exceeding 99.9% for singlequbit gates and exceeding 99% for twoqubit gates. These reported high numbers engender optimism that faulttolerant quantum computing is within reach. Here we convert reported gate fidelity to a bound on worst case quantum gate error rate, which is appropriate to assess progress towards faulttolerance targets and is greater by orders of magnitude. We prove that this bound scales optimally. Our work demonstrates the huge divide between reported gate fidelities and requisite gate performance.
http://research.microsoft.com/apps/video/default.aspx?id=250895
Barry Sanders
Science and Technology
Fri, 10 Jul 2015 16:40:00 GMT

Project Catapult: Derek Chiou and Bill Barth
http://research.microsoft.com/apps/video/default.aspx?id=251448
Arjmand Samuel; Derek Chiou; Bill Barth
Science and Technology
Fri, 10 Jul 2015 16:00:00 GMT

Advances in Quantum Algorithms and Devices: Welcome and Distributed Denstity Matrices
[Speakers: Krysta Svore and Rodney van Meter] The density matrix (d.m.) of a quantum state is a statistical construct, describing our best understanding of the actual state based on our prior experience with, and constant monitoring of, the experimental apparatus and its ability to store and manipulate quantum states. An operational problem arises when a multiparticle state is held in physically distributed locations and each node must make realtime decisions on the disposition of the quantum state, as in a quantum repeater network. Each node holding part of the state may independently choose to manipulate the state, affecting its fidelity. Software systems must concern themselves with the discrepancy between (in a twoparty state) Alice's notion of the d.m., Bob's notion of the d.m., and the d.m. that would be compiled by an observer Orville not subject to relativistic constraints on information. We have developed a set of principles for guiding the implementation, and compare four methods for meeting the constraints: by contract, by centralized control, by distributed calculation and decision, and by direct monitoring.
http://research.microsoft.com/apps/video/default.aspx?id=250897
Krysta Svore; Rodney van Meter
Science and Technology
Fri, 10 Jul 2015 15:30:00 GMT

Integrative AI: Panel
[Speakers: Charles Rich, Dan Bohus, Eric Horvitz, Larry Zitnick, Lidong Zhou, and Manuela Veloso] The panel will discuss challenges and opportunities in integrative AI, an area concerned with the development of systems that efficiently and robustly integrate multiple AI technologies (e.g., vision, speech, learning, realtime control) and can act and interact in the open world. While over the past years we have seen significant progress on core AI technologies, the science of integrating these competencies into larger systems that are robust, transparent, and maintainable remains very much in its infancy. Numerous research and engineering questions come to the fore: from algorithmic challenges in multimodal representations and modeling, to the science of systems that selfmonitor, diagnose their limitations and improve through interaction, all the way to the necessity of research platforms, data, and broader community efforts in this space.
http://research.microsoft.com/apps/video/default.aspx?id=251616
Charles Rich; Dan Bohus; Eric Horvitz; Larry Zitnick; Lidong Zhou; Manuela Veloso
Science and Technology
Thu, 09 Jul 2015 22:00:00 GMT

Semantics and Knowledge Bases for NextGeneration Scholarly Discovery
[Speakers: Alex Wade, C. Lee Giles, Jie Tang, Kuansan Wang, Oren Etzioni, and Yang Song] As web search is becoming more and more structured thanks to the availability of knowledge bases, scholar engines are also evolving towards that direction while facing the similar challenges and issues. This session will focus on bridging the gap between unstructured text and structured relationships to create new sematic scholar engines. We hope this session can serve as a discussion forum to bring together researchers from both academia and industrial labs from different disciplines to work together and exchange ideas on how to jointly optimize scholar engines and knowledge base systems while sharing their respective experiences in dealing with common issues in both areas.
http://research.microsoft.com/apps/video/default.aspx?id=251443
Alex Wade; C. Lee Giles; Jie Tang; Kuansan Wang; Oren Etzioni; Yang Song
Science and Technology
Thu, 09 Jul 2015 22:00:00 GMT