@article{18371, abstract = {We consider the problem of exact and inexact matching of weighted undirected graphs, in which a bijective correspondence is sought to minimize a quadratic weight disagreement. This computationally challenging problem is often relaxed as a convex quadratic program, in which the space of permutations is replaced by the space of doubly stochastic matrices. However, the applicability of such a relaxation is poorly understood. We define a broad class of friendly graphs characterized by an easily verifiable spectral property. We prove that for friendly graphs, the convex relaxation is guaranteed to find the exact isomorphism or certify its inexistence. This result is further extended to approximately isomorphic graphs, for which we develop an explicit bound on the amount of weight disagreement under which the relaxation is guaranteed to find the globally optimal approximate isomorphism. We also show that in many cases, the graph matching problem can be further harmlessly relaxed to a convex quadratic program with only n separable linear equality constraints, which is substantially more efficient than the standard relaxation involving 2n equality and n2 inequality constraints. Finally, we show that our results are still valid for unfriendly graphs if additional information in the form of seeds or attributes is allowed, with the latter satisfying an easy to verify spectral characteristic.}, author = {Aflalo, Yonathan and Bronstein, Alexander and Kimmel, Ron}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences}, number = {10}, pages = {2942--2947}, publisher = {National Academy of Sciences}, title = {{On convex relaxation of graph isomorphism}}, doi = {10.1073/pnas.1401651112}, volume = {112}, year = {2015}, } @inproceedings{1838, abstract = {Synthesis of program parts is particularly useful for concurrent systems. However, most approaches do not support common design tasks, like modifying a single process without having to re-synthesize or verify the whole system. Assume-guarantee synthesis (AGS) provides robustness against modifications of system parts, but thus far has been limited to the perfect information setting. This means that local variables cannot be hidden from other processes, which renders synthesis results cumbersome or even impossible to realize.We resolve this shortcoming by defining AGS under partial information. We analyze the complexity and decidability in different settings, showing that the problem has a high worstcase complexity and is undecidable in many interesting cases. Based on these observations, we present a pragmatic algorithm based on bounded synthesis, and demonstrate its practical applicability on several examples.}, author = {Bloem, Roderick and Chatterjee, Krishnendu and Jacobs, Swen and Könighofer, Robert}, location = {London, United Kingdom}, pages = {517 -- 532}, publisher = {Springer}, title = {{Assume-guarantee synthesis for concurrent reactive programs with partial information}}, doi = {10.1007/978-3-662-46681-0_50}, volume = {9035}, year = {2015}, } @inproceedings{18380, abstract = {This work presents a novel approach for detecting inliers in a given set of correspondences (matches). It does so without explicitly identifying any consensus set, based on a method for inlier rate estimation (IRE). Given such an estimator for the inlier rate, we also present an algorithm that detects a globally optimal transformation. We provide a theoretical analysis of the IRE method using a stochastic generative model on the continuous spaces of matches and transformations. This model allows rigorous investigation of the limits of our IRE method for the case of 2D-translation, further giving bounds and insights for the more general case. Our theoretical analysis is validated empirically and is shown to hold in practice for the more general case of 2D-affinities. In addition, we show that the combined framework works on challenging cases of 2D-homography estimation, with very few and possibly noisy inliers, where RANSAC generally fails.}, author = {Litman, Roee and Korman, Simon and Bronstein, Alexander and Avidan, Shai}, booktitle = {2015 IEEE Conference on Computer Vision and Pattern Recognition (CVPR)}, isbn = {9781467369640}, issn = {1063-6919}, location = {Boston, MA, United States}, publisher = {IEEE}, title = {{Inverting RANSAC: Global model detection via inlier rate estimation}}, doi = {10.1109/cvpr.2015.7299161}, year = {2015}, } @inproceedings{18387, abstract = {Sparse models in dictionary learning have been successfully applied in a wide variety of machine learning and computer vision problems, and have also recently been of increasing research interest. Another interesting related problem based on a linear equality constraint, namely the sparse null space problem (SNS), first appeared in 1986, and has since inspired results on sparse basis pursuit. In this paper, we investigate the relation between the SNS problem and the analysis dictionary learning problem, and show that the SNS problem plays a central role, and may be utilized to solve dictionary learning problems. Moreover, we propose an efficient algorithm of sparse null space basis pursuit, and extend it to a solution of analysis dictionary learning. Experimental results on numerical synthetic data and real-world data are further presented to validate the performance of our method.}, author = {Bian, Xiao and Krim, Hamid and Bronstein, Alexander and Dai, Liyi}, booktitle = {2015 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)}, issn = {2379-190X}, location = {South Brisbane, QLD, Australia}, publisher = {IEEE}, title = {{Sparse null space basis pursuit and analysis dictionary learning for high-dimensional data analysis}}, doi = {10.1109/icassp.2015.7178678}, year = {2015}, } @inproceedings{1839, abstract = {We present MultiGain, a tool to synthesize strategies for Markov decision processes (MDPs) with multiple mean-payoff objectives. Our models are described in PRISM, and our tool uses the existing interface and simulator of PRISM. Our tool extends PRISM by adding novel algorithms for multiple mean-payoff objectives, and also provides features such as (i) generating strategies and exploring them for simulation, and checking them with respect to other properties; and (ii) generating an approximate Pareto curve for two mean-payoff objectives. In addition, we present a new practical algorithm for the analysis of MDPs with multiple mean-payoff objectives under memoryless strategies.}, author = {Brázdil, Tomáš and Chatterjee, Krishnendu and Forejt, Vojtěch and Kučera, Antonín}, location = {London, United Kingdom}, pages = {181 -- 187}, publisher = {Springer}, title = {{Multigain: A controller synthesis tool for MDPs with multiple mean-payoff objectives}}, doi = {10.1007/978-3-662-46681-0_12}, volume = {9035}, year = {2015}, } @article{1840, abstract = {In this paper, we present a method for reducing a regular, discrete-time Markov chain (DTMC) to another DTMC with a given, typically much smaller number of states. The cost of reduction is defined as the Kullback-Leibler divergence rate between a projection of the original process through a partition function and a DTMC on the correspondingly partitioned state space. Finding the reduced model with minimal cost is computationally expensive, as it requires an exhaustive search among all state space partitions, and an exact evaluation of the reduction cost for each candidate partition. Our approach deals with the latter problem by minimizing an upper bound on the reduction cost instead of minimizing the exact cost. The proposed upper bound is easy to compute and it is tight if the original chain is lumpable with respect to the partition. Then, we express the problem in the form of information bottleneck optimization, and propose using the agglomerative information bottleneck algorithm for searching a suboptimal partition greedily, rather than exhaustively. The theory is illustrated with examples and one application scenario in the context of modeling bio-molecular interactions.}, author = {Geiger, Bernhard and Petrov, Tatjana and Kubin, Gernot and Koeppl, Heinz}, issn = {0018-9286}, journal = {IEEE Transactions on Automatic Control}, number = {4}, pages = {1010 -- 1022}, publisher = {IEEE}, title = {{Optimal Kullback-Leibler aggregation via information bottleneck}}, doi = {10.1109/TAC.2014.2364971}, volume = {60}, year = {2015}, } @inproceedings{18400, abstract = {We propose a method and a prototype imaging system for real-time reconstruction of volumetric piecewise-smooth scattering media. The volume is illuminated by a sequence of structured binary patterns emitted from a fan beam projector, and the scattered light is collected by a two-dimensional sensor, thus creating an under-complete set of compressed measurements. We show a fixed-complexity and latency reconstruction algorithm capable of estimating the scattering coefficients in real-time. We also show a simple greedy algorithm for learning the optimal illumination patterns. Our results demonstrate faithful reconstruction from highly compressed measurements. Furthermore, a method for compressed registration of the measured volume to a known template is presented, showing excellent alignment with just a single projection. Though our prototype system operates in visible light, the presented methodology is suitable for fast x-ray scattering imaging, in particular in real-time vascular medical imaging.}, author = {Menashe, Ohad and Bronstein, Alexander}, booktitle = {2014 IEEE International Conference on Image Processing (ICIP)}, issn = {2381-8549}, location = {Paris, France}, publisher = {IEEE}, title = {{Real-time compressed imaging of scattering volumes}}, doi = {10.1109/icip.2014.7025264}, year = {2015}, } @inproceedings{18401, abstract = {Intel's newly-announced low-cost RealSense 3D camera claims significantly better precision than other currently available low-cost platforms and is expected to become ubiquitous in laptops and mobile devices starting this year. In this paper, we demonstrate for the first time that the RealSense camera can be easily converted into a real low-cost gaze tracker. Gaze has become increasingly relevant as an input for human-computer interaction due to its association with attention. It is also critical in clinical mental health diagnosis. We present a novel 3D gaze and fixation tracker based on the eye surface geometry captured with the RealSense 3D camera. First, eye surface 3D point clouds are segmented to extract the pupil center and iris using registered infrared images. With non-ellipsoid eye surface and single fixation point assumptions, pupil centers and iris normal vectors are used to first estimate gaze (for each eye), and then a single fixation point for both eyes simultaneously using a RANSAC-based approach. With a simple learned bias field correction model, the fixation tracker demonstrates mean error of approximately 1 cm at 20-30 cm, which is sufficiently adequate for gaze and fixation tracking in human-computer interaction and mental health diagnosis applications.}, author = {Draelos, Mark and Qiu, Qiang and Bronstein, Alexander and Sapiro, Guillermo}, booktitle = {2015 IEEE International Conference on Image Processing (ICIP)}, location = {Quebec City, QC, Canada}, publisher = {IEEE}, title = {{Intel realsense = Real low cost gaze}}, doi = {10.1109/icip.2015.7351256}, year = {2015}, } @article{1841, abstract = {We propose a new family of message passing techniques for MAP estimation in graphical models which we call Sequential Reweighted Message Passing (SRMP). Special cases include well-known techniques such as Min-Sum Diffusion (MSD) and a faster Sequential Tree-Reweighted Message Passing (TRW-S). Importantly, our derivation is simpler than the original derivation of TRW-S, and does not involve a decomposition into trees. This allows easy generalizations. The new family of algorithms can be viewed as a generalization of TRW-S from pairwise to higher-order graphical models. We test SRMP on several real-world problems with promising results.}, author = {Kolmogorov, Vladimir}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, number = {5}, pages = {919 -- 930}, publisher = {IEEE}, title = {{A new look at reweighted message passing}}, doi = {10.1109/TPAMI.2014.2363465}, volume = {37}, year = {2015}, } @article{18415, abstract = {Parsimony, including sparsity and low rank, has been shown to successfully model data in numerous machine learning and signal processing tasks. Traditionally, such modeling approaches rely on an iterative algorithm that minimizes an objective function with parsimony-promoting terms. The inherently sequential structure and data-dependent complexity and latency of iterative optimization constitute a major limitation in many applications requiring real-time performance or involving large-scale data. Another limitation encountered by these modeling techniques is the difficulty of their inclusion in discriminative learning scenarios. In this work, we propose to move the emphasis from the model to the pursuit algorithm, and develop a process-centric view of parsimonious modeling, in which a learned deterministic fixed-complexity pursuit process is used in lieu of iterative optimization. We show a principled way to construct learnable pursuit process architectures for structured sparse and robust low rank models, derived from the iteration of proximal descent algorithms. These architectures learn to approximate the exact parsimonious representation at a fraction of the complexity of the standard optimization methods. We also show that appropriate training regimes allow to naturally extend parsimonious models to discriminative settings. State-of-the-art results are demonstrated on several challenging problems in image and audio processing with several orders of magnitude speed-up compared to the exact optimization algorithms.}, author = {Sprechmann, P. and Bronstein, Alexander and Sapiro, G.}, issn = {1939-3539}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, number = {9}, pages = {1821--1833}, publisher = {IEEE}, title = {{Learning efficient sparse and low rank models}}, doi = {10.1109/tpami.2015.2392779}, volume = {37}, year = {2015}, } @article{18416, abstract = {We construct an extension of spectral and diffusion geometry to multiple modalities through simultaneous diagonalization of Laplacian matrices. This naturally extends classical data analysis tools based on spectral geometry, such as diffusion maps and spectral clustering. We provide several synthetic and real examples of manifold learning, object classification, and clustering, showing that the joint spectral geometry better captures the inherent structure of multi-modal data. We also show the relation of many previous approaches for multimodal manifold analysis to our framework.}, author = {Eynard, Davide and Kovnatsky, Artiom and Bronstein, Michael M. and Glashoff, Klaus and Bronstein, Alexander}, issn = {1939-3539}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, number = {12}, pages = {2505--2517}, publisher = {IEEE}, title = {{Multimodal manifold snalysis by simultaneous diagonalization of Laplacians}}, doi = {10.1109/tpami.2015.2408348}, volume = {37}, year = {2015}, } @article{18424, abstract = {We present a fast algorithm for global rigid symmetry detection with approximation guarantees. The algorithm is guaranteed to find the best approximate symmetry of a given shape, to within a user-specified threshold, with very high probability. Our method uses a carefully designed sampling of the transformation space, where each transformation is efficiently evaluated using a sublinear algorithm. We prove that the density of the sampling depends on the total variation of the shape, allowing us to derive formal bounds on the algorithm's complexity and approximation quality. We further investigate different volumetric shape representations (in the form of truncated distance transforms), and in such a way control the total variation of the shape and hence the sampling density and the runtime of the algorithm. A comprehensive set of experiments assesses the proposed method, including an evaluation on the eight categories of the COSEG data set. This is the first large-scale evaluation of any symmetry detection technique that we are aware of.}, author = {Korman, Simon and Litman, Roee and Avidan, Shai and Bronstein, Alexander}, issn = {1467-8659}, journal = {Computer Graphics Forum}, number = {1}, pages = {2--13}, publisher = {Wiley}, title = {{Probably approximately symmetric: Fast rigid symmetry detection with global guarantees}}, doi = {10.1111/cgf.12454}, volume = {34}, year = {2015}, } @article{18425, abstract = {The recent introduction of 3D shape analysis frameworks able to quantify the deformation of a shape into another in terms of the variation of real functions yields a new interpretation of the 3D shape similarity assessment and opens new perspectives. Indeed, while the classical approaches to similarity mainly quantify it as a numerical score, map-based methods also define (dense) shape correspondences. After presenting in detail the theoretical foundations underlying these approaches, we classify them by looking at their most salient features, including the kind of structure and invariance properties they capture, as well as the distances and the output modalities according to which the similarity between shapes is assessed and returned. We also review the usage of these methods in a number of 3D shape application domains, ranging from matching and retrieval to annotation and segmentation. Finally, the most promising directions for future research developments are discussed.}, author = {Biasotti, S. and Cerri, A. and Bronstein, Alexander and Bronstein, M.}, issn = {1467-8659}, journal = {Computer Graphics Forum}, number = {6}, pages = {87--119}, publisher = {Wiley}, title = {{Recent trends, applications, and perspectives in 3D shape similarity assessment}}, doi = {10.1111/cgf.12734}, volume = {35}, year = {2015}, } @article{18436, author = {Haim, Harel and Bronstein, Alexander and Marom, Emanuel}, issn = {1094-4087}, journal = {Optics Express}, number = {19}, pages = {24547 -- 24556}, publisher = {Optica Publishing Group}, title = {{Computational multi-focus imaging combining sparse model with color dependent phase mask}}, doi = {10.1364/oe.23.024547}, volume = {23}, year = {2015}, } @inproceedings{18439, abstract = {Intel’s newly-announced low-cost and high precision RealSense 3D (RGBD) camera is becoming ubiquitous in laptops and mobile devices starting this year, opening the door for new applications in the mobile health arena. In this paper, we demonstrate how the Intel RealSense 3D camera can be used for low-cost gaze tracking and passive pulse rate estimation. We develop a novel 3D gaze and fixation tracker based on the eye surface geometry as well as an illumination invariant pulse rate estimation method using near-infrared images captured with RealSense. We achieve a mean error of 1cm at 20 − 30cm for the gaze tracker and 2.26bpm (beats per minute) for pulse estimation, which is adequate in many medical applications, demonstrating the great potential of novel consumer-grade RGBD technology in mobile health.}, author = {Qiu, Qiang and Chang, Zhuoqing and Draelos, Mark and Chen, Jie and Bronstein, Alexander and Sapiro, Guillermo}, booktitle = {Proceedings of the 5th EAI International Conference on Wireless Mobile Communication and Healthcare}, isbn = {9781631900884}, location = {London, United Kingdom}, publisher = {ICST}, title = {{Low-cost gaze and pulse analysis using realsense}}, doi = {10.4108/eai.14-10-2015.2261657}, year = {2015}, } @article{1845, abstract = {Based on extrapolation from excitatory synapses, it is often assumed that depletion of the releasable pool of synaptic vesicles is the main factor underlying depression at inhibitory synapses. In this issue of Neuron, using subcellular patch-clamp recording from inhibitory presynaptic terminals, Kawaguchi and Sakaba (2015) show that at Purkinje cell-deep cerebellar nuclei neuron synapses, changes in presynaptic action potential waveform substantially contribute to synaptic depression. Based on extrapolation from excitatory synapses, it is often assumed that depletion of the releasable pool of synaptic vesicles is the main factor underlying depression at inhibitory synapses. In this issue of Neuron, using subcellular patch-clamp recording from inhibitory presynaptic terminals, Kawaguchi and Sakaba (2015) show that at Purkinje cell-deep cerebellar nuclei neuron synapses, changes in presynaptic action potential waveform substantially contribute to synaptic depression.}, author = {Vandael, David H and Espinoza Martinez, Claudia and Jonas, Peter M}, journal = {Neuron}, number = {6}, pages = {1149 -- 1151}, publisher = {Elsevier}, title = {{Excitement about inhibitory presynaptic terminals}}, doi = {10.1016/j.neuron.2015.03.006}, volume = {85}, year = {2015}, } @article{1846, abstract = {Modal transition systems (MTS) is a well-studied specification formalism of reactive systems supporting a step-wise refinement methodology. Despite its many advantages, the formalism as well as its currently known extensions are incapable of expressing some practically needed aspects in the refinement process like exclusive, conditional and persistent choices. We introduce a new model called parametric modal transition systems (PMTS) together with a general modal refinement notion that overcomes many of the limitations. We investigate the computational complexity of modal and thorough refinement checking on PMTS and its subclasses and provide a direct encoding of the modal refinement problem into quantified Boolean formulae, allowing us to employ state-of-the-art QBF solvers for modal refinement checking. The experiments we report on show that the feasibility of refinement checking is more influenced by the degree of nondeterminism rather than by the syntactic restrictions on the types of formulae allowed in the description of the PMTS.}, author = {Beneš, Nikola and Kretinsky, Jan and Larsen, Kim and Möller, Mikael and Sickert, Salomon and Srba, Jiří}, journal = {Acta Informatica}, number = {2-3}, pages = {269 -- 297}, publisher = {Springer}, title = {{Refinement checking on parametric modal transition systems}}, doi = {10.1007/s00236-015-0215-4}, volume = {52}, year = {2015}, } @article{1847, author = {Grones, Peter and Friml, Jiřĺ}, journal = {Molecular Plant}, number = {3}, pages = {356 -- 358}, publisher = {Elsevier}, title = {{ABP1: Finally docking}}, doi = {10.1016/j.molp.2014.12.013}, volume = {8}, year = {2015}, } @article{1848, abstract = {The ability to escape apoptosis is a hallmark of cancer-initiating cells and a key factor of resistance to oncolytic therapy. Here, we identify FAM96A as a ubiquitous, evolutionarily conserved apoptosome-activating protein and investigate its potential pro-apoptotic tumor suppressor function in gastrointestinal stromal tumors (GISTs). Interaction between FAM96A and apoptotic peptidase activating factor 1 (APAF1) was identified in yeast two-hybrid screen and further studied by deletion mutants, glutathione-S-transferase pull-down, co-immunoprecipitation and immunofluorescence. Effects of FAM96A overexpression and knock-down on apoptosis sensitivity were examined in cancer cells and zebrafish embryos. Expression of FAM96A in GISTs and histogenetically related cells including interstitial cells of Cajal (ICCs), “fibroblast-like cells” (FLCs) and ICC stem cells (ICC-SCs) was investigated by Northern blotting, reverse transcription—polymerase chain reaction, immunohistochemistry and Western immunoblotting. Tumorigenicity of GIST cells and transformed murine ICC-SCs stably transduced to re-express FAM96A was studied by xeno- and allografting into immunocompromised mice. FAM96A was found to bind APAF1 and to enhance the induction of mitochondrial apoptosis. FAM96A protein or mRNA was dramatically reduced or lost in 106 of 108 GIST samples representing three independent patient cohorts. Whereas ICCs, ICC-SCs and FLCs, the presumed normal counterparts of GIST, were found to robustly express FAM96A protein and mRNA, FAM96A expression was much reduced in tumorigenic ICC-SCs. Re-expression of FAM96A in GIST cells and transformed ICC-SCs increased apoptosis sensitivity and diminished tumorigenicity. Our data suggest FAM96A is a novel pro-apoptotic tumor suppressor that is lost during GIST tumorigenesis.}, author = {Schwamb, Bettina and Pick, Robert and Fernández, Sara and Völp, Kirsten and Heering, Jan and Dötsch, Volker and Bösser, Susanne and Jung, Jennifer and Beinoravičiute Kellner, Rasa and Wesely, Josephine and Zörnig, Inka and Hammerschmidt, Matthias and Nowak, Matthias and Penzel, Roland and Zatloukal, Kurt and Joos, Stefan and Rieker, Ralf and Agaimy, Abbas and Söder, Stephan and Reid Lombardo, Kmarie and Kendrick, Michael and Bardsley, Michael and Hayashi, Yujiro and Asuzu, David and Syed, Sabriya and Ördög, Tamás and Zörnig, Martin}, journal = {International Journal of Cancer}, number = {6}, pages = {1318 -- 1329}, publisher = {Wiley}, title = {{FAM96A is a novel pro-apoptotic tumor suppressor in gastrointestinal stromal tumors}}, doi = {10.1002/ijc.29498}, volume = {137}, year = {2015}, } @article{1849, abstract = {Cell polarity is a fundamental property of pro- and eukaryotic cells. It is necessary for coordination of cell division, cell morphogenesis and signaling processes. How polarity is generated and maintained is a complex issue governed by interconnected feed-back regulations between small GTPase signaling and membrane tension-based signaling that controls membrane trafficking, and cytoskeleton organization and dynamics. Here, we will review the potential role for calcium as a crucial signal that connects and coordinates the respective processes during polarization processes in plants. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.}, author = {Himschoot, Ellie and Beeckman, Tom and Friml, Jiřĺ and Vanneste, Steffen}, journal = {Biochimica et Biophysica Acta - Molecular Cell Research}, number = {9}, pages = {2168 -- 2172}, publisher = {Elsevier}, title = {{Calcium is an organizer of cell polarity in plants}}, doi = {10.1016/j.bbamcr.2015.02.017}, volume = {1853}, year = {2015}, }