אירועים והרצאות בפקולטה למדעי המחשב ע"ש הנרי ומרילין טאוב

Magnetic Resonance Imaging has revolutionized diagnostic medicine. It is an excellent tool for disease diagnosis and monitoring, offering superb soft tissue contrast and high anatomic resolution; unlike computed tomography (CT), it lacks of ionizing radiation. However MRI suffers from several shortcomings, one of which is the inherently slow data acquisition. This has limited the penetration of MRI to applications that require sharp images of fast moving small body parts, such as angiography, ca...
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Much ofMuch of the literature on rational cryptography focuses on analyzing the strategic properties of cryptographic protocols. However, due to the presence of computationally-bounded players and the asymptotic nature of cryptographic security, a definition of sequential rationality for this setting has thus far eluded researchers. We propose a new framework for overcoming these obstacles, and provide the first definitions of computational solution concepts that guarantee seque...
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We present several methods for multi-manifold data modeling, i.e., modeling data by mixtures of possibly intersecting manifolds. We focus on algorithms for the special case where the underlying manifolds are affine or linear subspaces. We emphasize various theoretical results supporting the performance of some of these algorithms, in particular their robustness to noise and outliers. We demonstrate how such theoretical insights guide us in practical choices and present applications of suc...
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Digital Gene Expression (DGE) profiling by next-generation sequencing (NGS) technologies has the potential of becoming the leading method for quantitative analysis of complete transcriptomes. While similar approaches have been implemented in the past by methods such as SAGE, one of the key advantages of NGS technologies is an extremely high throughput which enables accurate quantification over a wide dynamic range of transcript abundances, as well as relatively low sample preparation bias....
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The transition from analog to digital has revolutionized many fields over the past century – most notably computation and communication – and can be used to similarly revolutionize additive manufacturing technology. In contrast with continuous (analog) materials produced by traditional rapid prototyping, digital materials are composed of many discrete, self-aligning voxels placed in a massively parallel layer deposition process. Digital principles allow for perfect replication and zero noise...
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A fundamental problem in geometry processing is to characterize the possible transformations a shape can undergo, and still remain "the same". Such transformations are called isometries, since they preserve some notion of distance between all points on the shape. In many cases, however, especially when dealing with discrete shapes, approximate isometries better characterize the wealth of shapes which represent the same object, such as different poses of a character. Such maps are harder t...
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The integer 1 is the unity of multiplication. The integer 12 represents the senior high-school year. They surely are different in many respects. But distributed computing does not multiply, neither it attends school, so why should it distinguish between the two integers? I refer to the nice generalization of consensus introduced by Chaudhuri called k-set consensus. While in consensus processors vote for a unique participating processor to be their representative, in set consensus their vote m...
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We study the problem of bandwidth allocation with multiple interferences. In this problem the input consists of a set of users and a set of base stations. Each user has a list of requests, each consisting of a base station, a frequency demand, and a profit that may be gained by scheduling this request. The goal is to find a maximum profit set of user requests $\calS$ that satisfies the following conditions: 1) $\calS$ contains at most one request per user, 2) the frequency sets allotted to r...
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The problems of random projections and sparse reconstruction have much in common and individually received much attention. Surprisingly, until now they progressed in parallel and remained mostly separate. Here, we employ new tools from probability in Banach spaces that were successfully used in the context of sparse reconstruction to advance on an open problem in random pojections. In particular, we generalize and use an intricate result by Rudelson and Vershynin for sparse reconstruction ...
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Part I of the talk covered the new Israeli Copyright Act of 2007. This part of the talk will focus on Creative Commons Licenses. ...
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‏There's a big difference between looking at a photograph of a place and being there. But what if you had access to a database of every possible image of that place and could conjure up any view at will? With billions of photographs currently available online, the Internet is beginning to resemble such a database, capturing our world's sites from a huge number of vantage points and viewing conditions. For example, a Google image search for "notre dame" or "grand canyon" each return millions of...
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Submodular maximization generalizes many fundamental problems in discrete optimization, including Max-Cut in directed/undirected graphs, maximum coverage, maximum facility location and marketing over social networks. We consider the problem of maximizing any submodular function subject to $d$ knapsack constraints, where $d$ is a fixed constant. We establish a strong relation between the discrete problem and its continuous relaxation, obtained through {\em extension by expectation} of t...
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Sparse recovery, or compressive sensing, is the problem of approximating a vector x from a low-dimensional linear sketch Ax, where A is an m x n matrix with m ...
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Recently there was constructed locally-decodable codes of sub-exponential length. This result showed that these codes can handle up to one third fraction of errors. In this talk we show that the same codes can be locally unique-decoded from error rate upto half and locally list-decoded from error rate $1-\alpha$ for any $\alpha>0$, with only a constant number of queries and a constant alphabet size. This gives the first sub-exponential codes that can be locally list-decoded with a constant num...
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In this talk we will present three applications of conformal geometry to the problems of surface matching and comparison. In particular we will show how certain ideas originated in the theory of conformal geometry can be used to define novel metrics measuring dissimilarities and finding correspondences betweens pairs of surfaces automatically. The prominent rigidity of conformal mappings renders these metrics computationally efficient, add suggests that conformal geometry can pl...
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TBD...
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Visual communication often requires adaptation of the transmission bit-rate to the available channel bandwidth or display characteristics of the end users. In this work, requantization for transrating of MPEG video sequences and JPEG still images is analyzed. We show that both the rate and the distortion of requantized images and video depend mainly on the ratio between the new and the original quantization steps. Our analysis is based on the structure of the quantizer and the Laplace-like dist...
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A property of functions on a vector space is said to be linear-invariantif it is closed under linear transformations of the domain.Linear-invariant properties are some of the most well-studied propertiesin the field of property testing. Testable linear-invariant propertiescan always be characterized by so-called local constraints, and of latethere has been a rapidly developing body of research investigating thetestability of linear-invariant properties in terms of their descriptio...
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In this research, we address the problem of anomaly detection using remotely sensed spectral information collected by hyperspectral sensors. Anomaly detection algorithms first model the abundant material spectra (background). Then, every pixel spectrally different in a meaningful way from the background is declared to be an anomaly pixel. Two major approaches to statistical background modeling can be distinguished: “the local approach” and “the global approach”. Local algorithms...
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TBA...
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We introduce a system to compute both head orientation and gaze detection from a single image. The system uses a camera with fixed parameters and requires no user calibration. Our approach to head orientation is based on a geometrical model of the human face, and is derived from morphological and physiological data. Eye gaze detection is based on a geometrical model of the human eye. Two new algorithms are introduced that require either two or three feature points to be extracted...
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Cryptographic hash functions take a message of arbitrary length and generate a short fingerprint. Their main use are for digital signatures, due to their collision resistance property, i.e., that it is hard to find two different messages that have the same fingerprint. In this talk we present novel cryptanalysis techniques that we developed to attack hash functions. These techniques improve the functionality of differential attacks against the collision resistance property of the hash functions...
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Failure patterns in modern parallel and distributed system are not necessarily uniform. The notion of an adversary scheduler is a natural way to extend the classical wait-free and t-faulty models of computation. A well-established way to characterize an adversary is by its set of cores, where a core is any minimal set of processes that cannot all fail in any execution. We show that the protocol complex associated with an adversary is (c-2)-connected, where c is the size of the adversary's...
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The Cairo graphics library has become an integral part of open source graphics, being the bases for quality graphics in various projects, such as Gnome and Fire fox. This lecture will cover its abilities, future direction and give a brief intro to using it. ...
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A self-stabilizing algorithm is a distributed algorithm that converges to a legal solution from any initial configuration. Most self-stabilizing protocols rely on checking every neighbor of every processor continuously to detect inconsitencies. Such protocols have a high communication cost, especially in dense networks. We investigate the potential usefulness of gossip for improving the communication efficiency of self-stabilizing protocols. We present randomized low communication self-stabili...
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Identification of rare variants by resequencing is important both for detecting novel variations and for screening individuals for known disease alleles. New technologies enable low-cost resequencing of target regions, although it is still prohibitive to test more than a few individuals. We propose a novel pooling design that enables the recovery of novel or known rare alleles and their carriers in groups of individuals. The method is based on a Compressed Sensing (CS) approach, which is g...
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Goldberg, Hartline and Wright [SODA 2001] introduced the notion of 'competitive analysis' into 'auction theory' when dealing with 'unlimited supply', 'unit demand', 'single item' auctions. They proved that there exists random auctions that guaranty constant 'competitive ratio' and that no deterministic auction can guaranty that. Aggarwal, Fiat, Goldberg, Hartline, Immorlica and Sudan [STOC 2005] showed that the 2001 conclusion was wrong and that there exist deterministic asymmetric a...
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In this talk I plan to discuss some results on image representation and processing via geometric models, in two extreme scales: 1. The finest scale representation is usually called "vectorization". Here the models are analytic aggregates mainly constructed from edges and ridges, equipped with their "extended color profiles". We provide some experimental data stressing the importance of accurate and flexible ``color profiles" of edges and ridges in our visual perception. Accordingly, th...
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For any $0...
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SSDL & Linux – a Love story or a Battle field? In the talk I will describe the process of moving (almost) all the computers of SSDL (the System & Software Development Laboratory at the Computer science faculty - Technion) from Windows to Linux. I will talk about the rezones for the move and about the benefits & drawback of Linux from the administrator (that is me) point of view and from the student's point of view. It will be great if we will have some kind of ...
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Since the Global Positioning System (GPS) was established in the 1970s, navigation has become a much easier task. Indeed, the majority of navigation systems rely on the GPS signal for correcting the developing dead reckoning errors. However, GPS is unavailable or unreliable indoors, underwater, in urban environments, and on other planets. In these scenarios, one must use alternative techniques for updating the Inertial Navigation System (INS), or any other dead reckoning mechanism being used. T...
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In this talk we generalize the well-known Unsplittable Flow Problem (UFP) and show its applicability to the emerging Network Centric Operations (NCO) concept. While UFP's goal is to maximize the profit gained by accommodating independent flows, our generalization considers dependent flows. In the generalized problem, referred to as the Dependent Unsplittable Flow Problem (D-UFP), the profit from delivering two flows is not necessarily equal to the sum of their profits. We show that i...
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Transcription and Classification of Audio Data by sparse Representations and Geometric Methods ...
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In this talk I shall cover two concepts related to protecting your information, cryptographic file system and steganographic file system. A cryptographic file system is a file system where the data stored is encrypted by the operating system (thus, protecting the confidentiality of the information in case the hard disk is taken away). A steganographic file system is a file system which is hidden from prying eyes, namely, that a person holding the hard disk cannot even find the files. ...
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Graph polynomials are powerful and well-developed tools to express graph parameters. Usually graph polynomials are compared to each other by ad-hoc means allowing to decide whether a newly defined graph polynomial generalizes (or is generalized) by another one. We study their distinctive power and introduce the notions of $dp$-completeness and universality of graph polynomials in order to formalize dependencies between them. Many known graph polynomials satisfy linear recurrence relations wit...
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In this talk, I will present my personal perspective on software testing and quality, a perspective which is torn between being an academic interested in programming languages, and my earthly experience, working for the last two years as a programmer in the trenches with Google and IBM. This talk is a re-run of an invited talk at HVC'10 conference. (*) As will be explained in my talk, the term "schizophrenic" is used here in a non-politically correct-, non-...
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Should penalized least squares regression be interpreted as Maximum A Posteriori estimation? Penalized least squares regression is often used for signal denoising and inverse problems, and is commonly interpreted in a Bayesian framework as a Maximum A Posteriori (MAP) estimator, the penalty function being the negative logarithm of the prior. For example, the widely used quadratic program (with an $\ell^1$ penalty) associated to the LASSO / Basis Pursuit Denoising is very often consid...
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In this talk I'll present some research topics supervised by me during the last 10 years in VHLab, mainly in the context of Virtual Humans, and, more recently, in computer vision (CV) integrated with computer graphics (CG). Firstly, I'll discuss topics focused on virtual humans simulation and open problems. Then, integration between CG and CV is presented, applied in practical and relevant areas. ...
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Signal models are used for a wide array of signal and image processing tasks – from deconvolution, denoising, and interpolation to source separation, super-resolution, and compression. One of the most common modeling approaches utilizes a dictionary of atomic signals, describing the set of elementary behaviors observed in the signals of interest. The dictionary is used either as an analysis operator, measuring the inner-products of the atoms and the input signal, or as a synthesis operator, re...
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Following the advances in the cryptanalysis of hash functions in the last years, and especially the alarming results on SHA1 and Merkle-Damgard hash functions, NIST has started a cryptographic competition to offer secure and fast hash function standard, to be named SHA3. The competition, currently at its second phase (with 14 remaining candidates), is the focus of many efforts in cryptanalysis and implementation. In this talk, we shall cover some of the aspects of this compe...
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Blind source separation of images and voice signals is a well known and well studied subject. Solutions for this problem have various applications, such as separation of voices of multiple speakers in the same room, denoising, separation of reflections superimposed on images, and more. Classical time/position invariant Blind Source Separation is usually solved using Independent Component Analysis (ICA), which tries to find statistically independent signals as a linear combination of the mixed ...
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In this talk, we present novel approaches for mapping surfaces and volumes to corresponding canonical domains with the same topology. In general we wish to find a bijection of the sampled surface or volume lying in 3D space with a simpler model, that respectively preserves the area or volume distribution and minimally distort the local geometry. Many of the operations we wish to perform on the discrete surface or volume, for processing, analysis or visualization, may be greatly simplified if we...
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Cancer is a worldwide burden with several million deaths annually and the situation is set to worsen globally as the population ages, with a projected increase of 45% to 2030 according to the WHO. Current cancer management is mainly focused on intervention after tumors have been detected; however, there is a drive towards very early detection and intervention to reduce the risk of metastatic disease. Novel methodology is emerging to allow modulation of tumor progression through targeting o...
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YouTube movies, live streaming, TV broadcast, conference calls and more - there is no doubt that video sequences are abundant and in everyday use. However, the quality of these videos is rarely satisfactory. This may be the result of network limitations, low-quality imaging devices and more. Improving the quality of videos has been long studied by the research community. Rather than independently improving the quality of each image in the sequence, it has been observed that temporal...
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The talk addresses the analysis of multi-spectral retinal image sets and hyperspectral satellite images. Pixels in such image sets represent mixtures of pure substances, called endmembers. The linear mixture model for hyperspectral imaging assumes that each pixel is a linear combination of the spectra of a collection of endmembers. To demix each pixel, these endmembers must be identified. A novel parallel algorithm to extract endmembers and demix each pixel is presented. Typical a...
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Recent advances in microscopy have enabled the collection of large amounts of microscopic data at rapid rates. The size and rate of acquisition of these "high throughput" microscopic data sets present new opportunities in understanding the structure and function of organs, but also present new challenges in the processing, analysis, and visualization of the data. This talk will describe some of the challenges and opportunities coming from an effort to reconstruct the mouse brain. This talk will ...
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Since 2004, the Web Hypertext Application Technology Working Group (WHATWG) has been working on the next generation of HTML, the markup that makes up web documents. In this talk, we will dive into some of the new elements defined by HTML5, see examples of how behavior that used to require third party software can now be implemented using web standards, discuss the evolution of HTML, and explore the options of developing fully featured applications on top of the web application stack ...
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רשתית העין היא הרקמה העצבית הראשונה המעבדת את המידע החזותי במערכת הראיה הביולוגית. בעבודה זאת נערכו ניסויי מעבדה בהם נבדקה תגובת רשתית חיה מתוך נקודת מבט מרחבית על-ידי מדידה בו זמנית במספר רב של נקודות באמצעות מערך אלקטרודות. תחילה נבדק מהו משך הגירוי האופטימאלי ...
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Computation is playing an increasingly central role in how we capture and process our images, opening up richer forms of photography that go beyond conventional imaging. Recent examples include merging multiple shots to obtain seamless panoramas, 3D shape, deeper focus, or a wider range of tones. In this talk, I will argue that the future of photography lies in richer capture, paying special attention to our limited budget of light, time, and sensor throughput. By analyzing tradeoffs and limits ...
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Zemereshet is an Emergency Project for the Rescue and Electronic Documentation of Early Hebrew Music. It is a volunteer association of enthusiasts who have assumed the mission of preserving the songs that were written and sung in Hebrew from the beginning of the Zionist movement until the establishment of the State of Israel. To that end, they established a website with thousands of recordings, lyrics, and complementary information. Yair Even-Zohar's talk will present the project a...
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We discuss a variational methodology, which involves locally modeling of data from noisy samples, combined with global model parameter regularization. We show that this methodology encompasses many previously proposed algorithms, from the celebrated moving least squares methods to the globally optimal over-parametrization methods recently published for smoothing and optic flow estimation. However, the unified look at the range of problems and methods previously considered also suggests a wealth ...
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Valgrind is an extremely powerful development tool, which detects and pin-points many common programming errors when running a program. Some examples for the problems it handles are many kinds of buffer overflows, using uninitialized data, accessing freed memory and memory leaks. Valgrind does that without need for recompilation of the program, simply by adding "valgrind" to the beginning of the command line. To an outside observer, this could seem like magic. In this lecture, we will take a...
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We introduce a system for hyperspectral imaging based on micro-mirror array, that projects subsets of image pixels onto a prism (or diffraction grating), followed by a CCD-type sensor. This system allows generalized sampling schemes including compressed sensing. We acquire only a fraction of the samples that are required to obtain the full-resolution signal (hyperspectral cube in our case), and by means of non-linear optimization recover the underlying signal. We use a prior knowledge abo...
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GarlicSim is an ambitious open-source project in the field of scientific computing, specifically computer simulations. It attempts to redefine the way that people think about computer simulations, making a new standard for how simulations are created and used. GarlicSim is a platform for writing, running and analyzing simulations. It is general enough to handle any kind of simulation: Physics, game theory, epidemic spread, electronics, etc. You may be wondering, what do these simulations have in...
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Studying the behavior of the heat diffusion process on a manifold is emerging as an important tool for analyzing the geometry of the manifold. Unfortunately, the high complexity of the computation of the heat kernel - the key to the diffusion process - limits this type of analysis to 3D models of modest resolution. We show how to use the unique properties of the heat kernel of a discrete two dimensional manifold to overcome these limitations. Combining a multi-resolution approach with a no...
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An inherent characteristic of distributed systems is the lack of centralized control, which requires the components to coordinate their actions. This need is abstracted as the \emph{consensus} problem, in which each process has a binary input and should produce a binary output, such that all outputs agree. A difficulty in obtaining consensus arises from the possibility of process failures in practical systems. When combined with the lack of timing assumptions in asynchronous systems, it re...
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Barycentric coordinates are heavily used in computer graphics applications to generalize a set of given data values. Traditionally, the coordinates are required to satisfy a number of key properties, the first being that they are real. In this work we relax this requirement, allowing the barycentric coordinates to be complex numbers. This allows us to generate new families of barycentric coordinates, which have some powerful advantages over traditional ones and are especially useful for creating...
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The Bag-of-Words (BoW) model is often used for recognition of objects, scenes, actions and more. It achieves impressive results in many diff erent areas, although it discards the spatial and temporal order of codewords in a labeled signal. This work is defi ning a new model: Contextual Sequence of Words (CSoW) which incorporates temporal order in a BoW model for video representation, and tests it on action recognition tasks. The temporal context is incorporated in three scales: global, med...
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Contrary to the vast majority of approaches to clustering, which view the problem as one of partitioning a set of observations into coherent classes, thereby obtaining the clusters as a by-product of the partitioning process, we propose to reverse the terms of the problem and attempt instead to derive a rigorous formulation of the very notion of a cluster. In our endeavor to provide an answer to this question, we found that game theory offers a very elegant and general perspective ...
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We propose a non-parametric probabilistic model for the automatic segmentation of medical images. The resulting inference algorithms register individual training images to the new image, transfer the segmentation labels and fuse them to obtain the final segmentation of the test subject. Our generative model yields previously proposed label fusion algorithms as special cases, but also leads to a new variant that aggregates evidence locally in determining the segmentation labels. We demonst...
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Natural videos, given in the RGB color space, are characterized by high correlations between the primary colors (R, G and B). To reduce this redundancy, most video compression algorithms, like MPEG, decorrelate the color components by transforming the input video from the highly correlated RGB components into less correlated space such as YIQ or YCbCr. In this work, we propose a different approach, which utilizes the natural high inter-color correlation. We have developed algorithms f...
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פרוייקט בן-יהודה הוא מיזם התנדבותי אשר בונה ומתחזק מאגר חופשי של יצירה עברית שאינה מוגנת בזכויות יוצרים. המהדורות האלקטרוניות של היצירות מוגשות לציבור בחינם, ללא פרסומות, והן נחלת הכלל (public domain), וזמינות לכל שימוש, לרבות שימוש מסחרי. על אף המראה הבסיסי והמיושן של האתר �...
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Aspect-oriented programming is becoming a common approach to extend object systems with modules that cross-cut the usual class hierarchy. Aspects encapsulate treatment of concerns that otherwise would be scattered within an underlying application, and tangled with code treating other concerns. Often, insertion of several aspects into one system is desired and in that case the problem of interference among the aspects might arise, even if each aspect individually woven is correct relat...
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While control via sensing in robotics and in human-robot interaction is important for both robot autonomous vehicles and arm manipulators, it is more prescient and less understood in robot arm manipulation tasks. Analysis of such systems suggests the following: * Mutual safety of humans vis-a-vie robots vis-a-vie other objects in an unstructured environment dictates a need for massive coverage of the whole robot body with sensors. * Achieving robot motion planning skills ...
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With parallel coordinates the perceptual barrier imposed by our 3-dimensional habitation is breached enabling the visualization of multidimensional problems. By learning to recognize patterns a powerful knowledge discovery process evolved. It leads to a deeper geometrical insight: the recognition of M-dimensional objects recursively from their (M-1)-dimensional subsets. A hyperplane in N-dimensions is represented by (N -1) indexed points. Points representing lines have two indices, th...
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The reconstruction of a surface from a set of planar cross-sections such that the surface interpolates, or approximates, the input has been thoroughly studied in the past decades. This problem arises mainly in the fields of medical imaging (MRI, CT, ultrasound etc.) and geographical information systems (for terrain reconstruction). The input is assumed to have been segmented in a preprocessing step, to create a set of closed two-dimensional contours, separating the ...
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יום העיון בקריפטולוגיה 2010 יתקיים ביום ד', 9 ביוני 2010, בין השעות 9.00-16.10, באודיטוריום 1, בניין טאוב למדעי המחשב, הטכניון. כולם מוזמנים. פרטים נוספים ותוכנית...
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Substantial familial aggregation and heritability is observed for a wide range of phenotypes in general human population. Much effort has been made to decipher which specific genetic factors contribute to normal interindividual variability and development of pathologic conditions. The lecture will focus on the workflow of a typical family-based genetic research, illustrated by the association study of RUNX2 polymorphisms and hand bone length and BMD, relevant to osteoporosis. The Program P...
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We would like to compute the motion of flexible materials colliding against each other in complex ways (e.g., sheets of fabric being knotted, plastic and metal containers crushed in a trash compactor). Such computations are needed in special effects, engineering design, medical simulation, and any other domain that requires consideration of materials interacting against each other. What is a "good" way to carry out such computations? What sets our approach apart from previous attempts...
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Protein function prediction is an active area of research in bioinformatics. And yet, transfer of annotation on the basis of sequence or structural similarity remains widely used in practice. Most of the machine learning methods applied to this problem reduce it to a collection of binary classification problems: whether a protein performs a particular function, sometimes with a post-processing step to combine the binary outputs. I will present the GOstruct method that directly predicts the...
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The celebrated Nash Embedding Theorem is extensively employed in recent years in various theoretical, as well as practical, aspects of Computer Graphics and Image Processing. However, in practice, this kind of application encounters certain obstructions, rendering the use of the Embedding Theorem as somewhat problematic. We explore therefore its practicability in Vision, Graphics and other Imaging sciences. As a solution for some of the problems mentioned above, the use of a PL version of the T...
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Difference Engine is an extension to Xen, which is an open-source hypervisor. The paper, titled "Difference Engine: Harnessing Memory Redundancy in Virtual Machines", by Diwaker Gupta, Sangmin Lee,Michael Vrable, Stefan Savage, Alex C. Snoeren, George Varghese, Geoffrey M. Voelker, and Amin Vahdat, won a best paper award in OSDI'08. I will not present the conference talk (which is just a taste, and for which slides are unavailable) but the full paper, including my comments on it. ...
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TBA...
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We propose a method for deriving enzymatic signatures from short read (SR) metagenomic data of unknown species. The SR data are converted to six pseudo-peptide candidates. We search for occurrences of Specific Peptides (SPs) on the latter. SPs are peptides that are indicative of enzymatic function as defined by the Enzyme Commission (EC) nomenclature. Counting their hits, we associate short reads with specific EC categories. The putative peptide counts can then be converted to estimates of...
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We consider the inverse problem of discovering the location of point sources from very sparse point measurements in a bounded domain that contains impenetrable (and possibly unknown) obstacles. We present our adaptive algorithm for determining the measurement locations, and ultimately, the source locations. ...
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We will address the problem of representing shapes using eigenvalues and eigenvectors of the discrete diffusion operator. A discrete shape, such as a mesh or a point cloud, can be viewed as an undirected weighted graph, hence one can use spectral graph theory to both embed and analyse shapes. We propose two graph diffusion operators that are built based on two widely used graph Laplacians: The combinatorial Laplacian and the normalized Laplacian. We recapitulate the basic spectral properties of...
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More detail in seminar poster פרטים נוספים...
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In recent years the data mining community has faced a new challenge. Having shown how effective its tools are in revealing the knowledge locked within huge databases, it is now required to develop methods that restrain the power of these tools to protect the privacy of individuals. This research focuses on the problem of guaranteeing privacy of data mining output. In the talk I will present some of the recent research results. We consider the problem of data mining with formal privacy guarante...
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Color information plays a major role in image processing and visual communication although presently most algorithms and tools are developed mainly for monochromatic images. Usually, the processing of color images is performed either in the RGB color space or in another color space chosen rather arbitrarily, such as YUV or YIQ. In this work we propose new frameworks for color image processing and coding based on an optimized approach. These frameworks along with rate-distortion analysis optimize...
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KDE was developed to give Unix applications a common look and feel. From 1996 to 2007 the desktop environment saw many improvements and changes. In January 2008 a rewrite of the entire desktop environment and many of it's core applications was performed. The rewrite, called KDE 4, led to a dramatic change in KDE's stance. Once noted for its configurablity, KDE 4 had significantly fewer options than previous KDE versions. Core applications and the desktop environment itself were missing critical ...
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Roy Migdal will present the work of Martin Vuagnoux and Sylvain Pasini, which won the best paper award at 18th USENIX Security Symposium (Usenix Security '09), Montreal, Canada, August 10-14, 2009. Computer keyboards are often used to transmit confidential data such as passwords. Since they contain electronic components, keyboards eventually emit electromagnetic waves. These emanations could reveal sensitive information such as keystrokes. The technique generally used to detect com...
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Non-rigid shape correspondence by matching semi-local spectral features and global geodesic structures Abstract: We present an efficient computational method for finding correspondences between non-rigid shapes. It utilizes both pointwise surface descriptors, and metric structures defined on the shapes to perform the matching task, which is formulated as a quadratic minimization problem. The suggested surface descriptors are based on eigendecomposition of the Laplace-Beltrami operator. It is als...
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A Bitonic sorter is a comparator network that sorts every Bitonic input sequence. In our research, we studied the minimal depth of such networks. Building on previous works, we establish that the minimal depth of a Bitonic sorter of n keys is 2ceiling(log(n)) -floor(log(n)). This result is constructive - that is, we present, for every n, a Bitonic sorter of that depth. In this talk I will also present other results from my PhD research....
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חקירה והתבוננות בעולם הטבע חוללה תובנות רבות בקרב החוקרים. נחילים בטבע, כמו גם בעלי חיים החיים בקבוצות שיתופיות, מציגים יכולות מרשימות בהשגת יעדים קבוצתיים, גם אם יכולות הפרטים בקהילה מוגבלות למדי. התמודדות עם בעיות מורכבות מדרבנת את החיפוש אחר פתרונות הכרוכים בהפעלה...
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We present the first results of an ongoing project revolving around approximation by finite element functions on adaptive and anisotropic triangulations, with application to image processing. We first recall the available theory for isotropic triangulations which involves Besov-Sobolev spaces. For anisotropic triangulations, we present an analytic criterion that governs the rate of convergence in Lp norms for optimally adapted triangulations. We propose a greedy algorithm which has...
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In this meeting we shall try and contact as many webmasters of as many websites that do not support Linux-based browsing (as well as OpenSource browsing in other OSes). The aim is to offer a great deal of "demand" to various websites, thus proving the importance of supporting wide range of platforms (and following the internet standards). Before the meeting, we shall have a list of websites and the contact details of the webmasters (including by phone). If you have a candidate, pleas...
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One of the critical stages in drug development is the identification of potential side effects for promising drug leads. Large scale clinical experiments aimed at discovering such side effects are very costly and may miss subtle or rare side effects. To date, and to the best of our knowledge, no computational approach was suggested to systematically tackle this challenge. In this work we report on a novel approach to predict the side effects of a given drug. Starting from a query drug, a c...
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TBA...
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Abstract: We propose a new approach to the simultaneous cooperative localization of a group of robots capable of sensing their own motion and the relative position of nearby robots. In the last decade, the use of distributed optimal Kalman filters (KF) to solve this problem have been studied extensively. In this paper, we propose to use a sub-optimal Kalman filter (denoted by EA). EA requires significantly less computation and communication resources then KF. Furthermore, in some cases, EA p...
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This research explores the identification of recurring constructs, Code Structures, which serve as the building blocks of object oriented programs and the exploitation of these in various areas including software research, development tools, and language design. Any in-depth research of these structures, be it an empirical study of existing programs or an analytical reasoning about software modules, must be based on some formal means for describing the elements of a program. To thi...
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In the 1997 paper "Polynomials with two values" by von zur Gathen and Roche (Combinatorica), the authors proved that the degree of any non-constant symmetric function of the form $f:{0,1}^n \rightarrow {0,1}$ is $n-o(n)$ (where the degree of a function is defined to be the degree of the unique interpolation polynomial, of degree at most $n$, of the function). In their proof, the authors heavily used the fact that the function is Boolean. The authors therefore asked what can be said about the...
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Apart from rendering photorealistic images many works in computer graphics focus on creating illustrative and artistic images. Such images can be used in many contexts ranging from CAD to planning and technical documentation. Finding mathematical principles and algorithms for aesthetic configurations is one important aspect for producing good illustrations. The talk will give an overview about this fascinating field between art and science, many examples will illustrate how close compuational ou...
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Fortran is the most known language for scientific and engineering problems. However growth of popularity of C/C++,Java, Matlab etc has shadowed the development and mere existence of Fortran from wider community. Situation may change know. Fortran 2003 standard provides all language features, one expects from modern programming language and gfortran which replaced g77 in gcc starting from version 4.0 implements this standard. Slides are...
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Recent years have seen intensive progress in measuring protein translation. However, the contributions of coding sequences to the efficiency of the process remain unclear. Here, we identify a universally conserved profile of translation efficiency along mRNAs computed based on adaptation between coding sequences and the tRNA pool. In this profile, the first ~30-50 codons are, on average, translated with a low efficiency. Additionally, in eukaryotes, the last ~50 codons show the highest e...
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The delivery of latency sensitive packets is a crucial issue in real time applications of communication networks. Such packets often have a firm deadline and a packet becomes useless if it arrives after its deadline. The deadline, however, applies only to the packet's journey through the entire network; individual routers along the packet's route face a more flexible deadline. We consider policies for admitting latency sensitive packets at a router. Each packet is tagged with a valu...
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Segmentation of organs and vascular structures from clinical Computed Tomography (CT) images is a crucial task in many clinical applications including diagnosis, patient specific training simulations, and intra-operative navigation. The segmentation is a challenging task due to the unclear distinction between the required structure and its surrounding tissue, artifacts in the CT images, and the presence of pathologies. We present a shape constrained graph min-cut approach for the segme...
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3D scanning is the process of acquiring a digital copy of a physical object. A 3D scanner is used to sample points on the surface of the object (the so-called underlying surface) and acquire their Cartesian coordinates, after which a surface reconstruction algorithm is applied to generate a surface based on this sample set. We define a generalized distance function on an unoriented 3D point set and describe how it may be used to reconstruct a surface approximating these points. ...
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In a paper of 1974 Dijkstra introduced the notion of self-stabilizing algorithms and presented three such algorithms for the problem of mutual exclusion on a ring of $n$ processors. The third algorithm is the most interesting of these three but is rather non intuitive. In 1986 a proof of its correctness was presented by Dijkstra, but the question of determining its worst case complexity --- that is, providing an upper bound on the number of moves of this algorithm until it stabilizes --- rem...
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Drupal is an open source content management system that developed into a web application framework written in PHP, it is used to build a wide variety of high-profile web sites, including open source projects like the Linux Journal, online news publishers like The New York Observer , and social networking communities like MTV UK. The talk will begin with an overview of Drupal: its capabilities and its usage profile. Some ready-to-use Drupal full-blown installs will be shown as well. The second ha...
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Code inspection is considered to be an efficient method for detecting some kinds of faults in software code documents. Other kinds of faults are more efficiently detected by other methods such as testing. It has therefore been suggested first to inspect the code and thereafter test it. The number of inspectors employed in the inspection should be determined to enable detection of most of the faults that inspection detects efficiently. The faults detected by the inspection will corrected, such t...
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Planning a course of action is a key ability for intelligent systems. It involves the representation of actions and world models, reasoning about the effects of actions, and techniques for efficiently searching the space of possible plans. Planning under uncertainty is captured by the area of decision-theoretic planning (DTP). In such problems, the actions have stochastic effects, and the goal is to devise a policy of acting with a high expected utility, as opposed to deterministic planning whic...
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VoIP is an emerging and exciting technology. We will deal with the basics of VoIP protocols and we will discuss some Linux VoIP applications. We will also discuss VOIP with cellular phones (like Android). VOIP protocols:- RTP - Real Time protocol. - RTCP - Real Time control protocol.  ...
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We examine the proof-theoretic strength of parameterized tree-like resolution---a proof system for the $\co\W[2]$-complete set of parameterized tautologies. Parameterized resolution and, moreover, a general framework for parameterized proof complexity was introduced by Dantchev, Martin, and Szeider (FOCS'07). In that paper, Dantchev et al.\ show a complexity gap in parameterized tree-like resolution for propositional formulas arising from translations of first-order princ...
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In this talk I will describe the algorithms and mechanisms underlying a distributed system for genetic linkage analysis, called Superlink-online. It is a production online system which serves hundreds of geneticists worldwide allowing for faster analysis of genetic data via automatic parallelization and execution on thousands of non-dedicated computers. I will describe the following innovative technologies forming the core of this system 1. Practical scheduling and execution of embarrassingl...
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Computing landscape is changing rapidly in the recent years. On the one hand, the pervasiveness of multiprocessor and multicore hardware requires the software to be able to take advantage of the increasingly available parallelism. On the other hand, the growing complexity of the modern software application domains makes runtime language environments more popular as a major software development tool. In this work, we investigate a question whether a garbage collector, being an important par...
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Metagenomics is a new field in which genetic material is extracted directly from the environment and is subsequently analyzed by a variety of biological and computational methods. Metagenomics makes it possible to study microbial communities directly from the environment and also to study microbial species that cannot be cultivated in the laboratory. Metagenomic data usually consists of many short (100-1,000 bp) DNA sequences, potentially originating from all organisms living in the examin...
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Hspell is a free Hebrew spell checker. It is used by most Linux distributions, by free applications such as OpenOffice and Firefox, and even by Google's popular Gmail service. Seven years after Hspell's first release, it is a good occasion to look back and see what made it successful. We will review Hspell's design, how it was works, and how it was developed. We will ask ourselves what allowed Hspell to be developed quickly, what ensured its quality, and what made it easy to adopt by all ...
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Geometric rearrangement of images includes operations such as image retargeting, object removal, or object rearrangement. Each such operation can be characterized by a shift-map: the relative shift of every pixel in the output image from its source in an input image. We describe a new representation of these operations as an optimal graph labeling, where the shift-map represents the selected label for each output pixel. Two terms are used in computing the optimal shift-map: (i) A data term whi...
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Fluorescence microscopy is a powerful tool in biology and biomedical sciences. Microscopic specimens usually yield fluorescence intensity images that are dim and thus suffer from low signal-to-noise ratio (SNR). Moreover, in multispectral imaging of fluorescing specimen, intensities are just a means to obtain information about molecular distributions of the materials in the specimen. Multiplexed sensing is a way for increasing the signal-to-noise ratio (SNR) of intensity data arrays,...
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What kind of community is it? Who are its members? What are its boundaries? מחקר זה מנסה להבין מהם התהליכים שהובילו להתכוננות קהילת הקוד הפתוח מתוך קבוצת האנשים הפעילים בפרוייקטים השונים. על אף שקהילת הקוד הפתוח נחקרה רבות מנקודת מבט טכנולוגית וארגונית, המחקר הסוציולוגי, היכול לתרום רבות להבנת התהל...
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The images acquired via medical imaging modalities are frequently subject to low signal-to-noise ratio, bias field and partial volume effects. These artifacts, together with the naturally low contrast between image intensities of some neighboring structures, make the extraction of regions of interest (ROIs) in clinical images a challenging problem. Probabilistic atlases, typically generated from comprehensive sets of manually labeled examples, facilitate the analysis by providing stat...
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Aspect-Oriented Programming (AOP) is a paradigm that allows the addition of new functionality to an existing system in a clean and modular fashion. In this research we utilize AOP to define support for the software development process within a development environment (Eclipse). AspectJ aspects that encapsulate software process support are defined and then integrated (woven) into the Eclipse code defining the development environment itself. Consequently, during the development, an Eclipse develo...
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We will discuss two important conjectures in additive combinatorics. The first one is the polynomial Freiman-Rusza conjecture, which relates to the structure of sets with small doubling. The second is the inverse Gowers conjecture for $U^3$, which relates to functions which locally look like quadratics. In both conjectures a weak form, with exponential decay of parameters is known, and a strong form with only a polynomial decay of parameters is conjectured. We will show that the...
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OFFSCHED is a platform aimed to assign an assignment to an offloaded processor. An offloaded processor is a processor that is hot un-plugged from the operating system. In today's computer world, we find that most processors have several embedded cores and hyper-threading. Most programmers do not really use these powerful features and let the operating system do the work. At most, a programmer will bound an application to a certain processor or assign an interrupt to a different processor....
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