Asia
Transfer Feature Representation via Multiple Kernel Learning
Wang, Wei (Institute of Software, Chinese Academy of Sciences) | Wang, Hao (Institute of Software, Chinese Academy of Sciences) | Zhang, Chen (Institute of Software, Chinese Academy of Sciences) | Xu, Fanjiang (Institute of Software, Chinese Academy of Sciences)
Learning an appropriate feature representation across source and target domains is one of the most effective solutions to domain adaptation problems. Conventional cross-domain feature learning methods rely on the Reproducing Kernel Hilbert Space (RKHS) induced by a single kernel. Recently, Multiple Kernel Learning (MKL), which bases classifiers on combinations of kernels, has shown improved performance in the tasks without distribution difference between domains. In this paper, we generalize the framework of MKL for cross-domain feature learning and propose a novel Transfer Feature Representation (TFR) algorithm. TFR learns a convex combination of multiple kernels and a linear transformation in a single optimization which integrates the minimization of distribution difference with the preservation of discriminating power across domains. As a result, standard machine learning models trained in the source domain can be reused for the target domain data. After rewritten into a differentiable formulation, TFR can be optimized by a reduced gradient method and reaches the convergence. Experiments in two real-world applications verify the effectiveness of our proposed method.
Online Dictionary Learning on Symmetric Positive Definite Manifolds with Vision Applications
Zhang, Shengping (Harbin Institute of Technology at Weihai) | Kasiviswanathan, Shiva (General Electric Global Research) | Yuen, Pong C. (Hong Kong Baptist University) | Harandi, Mehrtash (NICTA and Australian National University)
Symmetric Positive Definite (SPD) matrices in the form of region covariances are considered rich descriptors for images and videos. Recent studies suggest that exploiting the Riemannian geometry of the SPD manifolds could lead to improved performances for vision applications. For tasks involving processing large-scale and dynamic data in computer vision, the underlying model is required to progressively and efficiently adapt itself to the new and unseen observations. Motivated by these requirements, this paper studies the problem of online dictionary learning on the SPD manifolds. We make use of the Stein divergence to recast the problem of online dictionary learning on the manifolds to a problem in Reproducing Kernel Hilbert Spaces, for which, we develop efficient algorithms by taking into account the geometric structure of the SPD manifolds. To our best knowledge, our work is the first study that provides a solution for online dictionary learning on the SPD manifolds. Empirical results on both large-scale image classification task and dynamic video processing tasks validate the superior performance of our approach as compared to several state-of-the-art algorithms.
Strong Temporal Planning with Uncontrollable Durations: A State-Space Approach
Cimatti, Alessandro (Fondazione Bruno Kessler) | Micheli, Andrea (Fondazione Bruno Kessler) | Roveri, Marco (Fondazione Bruno Kesslerr)
In many practical domains, planning systems are required to reason about durative actions. A common assumption in the literature is that the executor is allowed to decide the duration of each action. However, this assumption may be too restrictive for applications. In this paper, we tackle the problem of temporal planning with uncontrollable action durations. We show how to generate robust plans,that guarantee goal achievement despite the uncontrollability of the actual duration of the actions. We extend the state-space temporalplanning framework, integrating recent techniques for solving temporalproblems under uncertainty. We discuss different ways of lifting the total order plans generated by the heuristic search to partial orderplans, showing (in)completeness results for each of them. We implemented our approach on top of COLIN, a state-of-the-art planner. An experimental evaluation over several benchmark problems shows the practical feasibility of the proposed approach.
Stable Feature Selection from Brain sMRI
Xin, Bo (Peking University) | Hu, Lingjing (Capital Medical University) | Wang, Yizhou (Peking University) | Gao, Wen (Peking University)
Neuroimage analysis usually involves learning thousands or even millions of variables using only a limited number of samples. In this regard, sparse models, e.g. the lasso, are applied to select the optimal features and achieve high diagnosis accuracy. The lasso, however, usually results in independent unstable features. Stability, a manifest of reproducibility of statistical results subject to reasonable perturbations to data and the model (Yu 2013), is an important focus in statistics, especially in the analysis of high dimensional data. In this paper, we explore a nonnegative generalized fused lasso model for stable feature selection in the diagnosis of Alzheimer's disease. In addition to sparsity, our model incorporates two important pathological priors: the spatial cohesion of lesion voxels and the positive correlation between the features and the disease labels. To optimize the model, we propose an efficient algorithm by proving a novel link between total variation and fast network flow algorithms via conic duality. Experiments show that the proposed nonnegative model performs much better in exploring the intrinsic structure of data via selecting stable features compared with other state-of-the-arts.
Multi-Task Learning and Algorithmic Stability
Zhang, Yu (Hong Kong Baptist University)
In this paper, we study multi-task algorithms from the perspective of the algorithmic stability. We give a definition of the multi-task uniform stability, a generalization of the conventional uniform stability, which measures the maximum difference between the loss of a multi-task algorithm trained on a data set and that of the multi-task algorithm trained on the same data set but with a data point removed in each task. In order to analyze multi-task algorithms based on multi-task uniform stability, we prove a generalized McDiarmid's inequality which assumes the difference bound condition holds by changing multiple input arguments instead of only one in the conventional McDiarmid's inequality. By using the generalized McDiarmid's inequality as a tool, we can analyze the generalization performance of general multi-task algorithms in terms of the multi-task uniform stability. Moreover, as applications, we prove generalization bounds of several representative regularized multi-task algorithms.
VecLP: A Realtime Video Recommendation System for Live TV Programs
Gao, Sheng (PRIS - Beijing University of Posts and Telecommunications) | Zhang, Dai (PRIS - Beijing University of Posts and Telecommunications) | Zhang, Honggang (PRIS - Beijing University of Posts and Telecommunications) | Huang, Chao (DOCOMO Beijing Communication Labs) | Zhang, Yongsheng (DOCOMO Beijing Communication Labs) | Liao, Jianxin (Beijing University of Posts and Telecommunications) | Guo, Jun (PRIS - Beijing University of Posts and Telecommunications)
We propose VecLP, a novel Internet Video recommendation system working for Live TV Programs in this paper. Given little information on the live TV programs, our proposed VecLP system can effectively collect necessary information on both the programs and the subscribers as well as a large volume of related online videos, and then recommend the relevant Internet videos to the subscribers. For that, the key frames are firstly detected from the live TV programs, and then visual and textual features are extracted from these frames to enhance the understanding of the TV broadcasts. Furthermore, by utilizing the subscribers' profiles and their social relationships, a user preference model is constructed, which greatly improves the diversity of the recommendations in our system. The subscriber's browsing history is also recorded and used to make a further personalized recommendation. This work also illustrates how our proposed VecLP system makes it happen. Finally, we dispose some sort of new recommendation strategies in use at the system to meet special needs from diverse live TV programs and throw light upon how to fuse these strategies.
Learning Predictable and Discriminative Attributes for Visual Recognition
Guo, Yuchen (Tsinghua Univerisity) | Ding, Guiguang (Tsinghua University) | Jin, Xiaoming (Tsinghua University) | Wang, Jianmin (Tsinghua University)
Utilizing attributes for visual recognition has attracted increasingly interest because attributes can effectively bridge the semantic gap between low-level visual features and high-level semantic labels. In this paper, we propose a novel method for learning predictable and discriminative attributes. Specifically, we require the learned attributes can be reliably predicted from visual features, and discover the inherent discriminative structure of data. In addition, we propose to exploit the intra-category locality of data to overcome the intra-category variance in visual data. We conduct extensive experiments on Animals with Attributes (AwA) and Caltech256 datasets, and the results demonstrate that the proposed method achieves state-of-the-art performance.
A Local Sparse Model for Matching Problem
Jiang, Bo (Anhui University) | Tang, Jin (Anhui University) | Ding, Chris (University of Texas at Arlington) | Luo, Bin (Anhui University)
Feature matching problem that incorporates pairwise constraints is usually formulated as a quadratic assignment problem (QAP). Since it is NP-hard, relaxation models are required. In this paper, we first formulate the QAP from the match selection point of view; and then propose a local sparse model for matching problem. Our local sparse matching (LSM) method has the following advantages: (1) It is parameter-free; (2) It generates a local sparse solution which is closer to a discrete matrix than most other continuous relaxation methods for the matching problem. (3) The one-to-one matching constraints are better maintained in LSM solution. Promising experimental results show the effectiveness of the Proposed LSM method.
Exact Recoverability of Robust PCA via Outlier Pursuit with Tight Recovery Bounds
Zhang, Hongyang (Peking University) | Lin, Zhouchen (Peking University) | Zhang, Chao (Peking University) | Chang, Edward Y. (HTC Research, Taiwan)
Subspace recovery from noisy or even corrupted data is critical for various applications in machine learning and data analysis. To detect outliers, Robust PCA (R PCA) via Outlier Pursuit was proposed and had found many successful applications. However, the current theoretical analysis on Outlier Pursuit only shows that it succeeds when the sparsity of the corruption matrix is of O(n/r), where n is the number of the samples and r is the rank of the intrinsic matrix which may be comparable to n. Moreover, the regularization parameter is suggested as 3/(7 squareroot gamma n}, where gamma is a parameter that is not known a priori. In this paper, with incoherence condition and proposed ambiguity condition we prove that Outlier Pursuit succeeds when the rank of the intrinsic matrix is of O(n log n) and the sparsity of the corruption matrix is of O(n). We further show that the orders of both bounds are tight. Thus R-PCA via Outlier Pursuit is able to recover intrinsic matrix of higher rank and identify much denser corruptions than what the existing results could predict. Moreover, we suggest that the regularization parameter be chosen as 1 squareroot{log n}, which is definite. Our analysis waives the necessity of tuning the regularization parameter and also significantly extends the working range of the Outlier Pursuit. Experiments on synthetic and real data verify our theories.
Planning Over Multi-Agent Epistemic States: A Classical Planning Approach
Muise, Christian (University of Melbourne) | Belle, Vaishak (University of Toronto) | Felli, Paolo (University of Melbourne) | McIlraith, Sheila (University of Toronto) | Miller, Tim (University of Melbourne) | Pearce, Adrian R. (University of Melbourne) | Sonenberg, Liz (University of Melbourne)
Many AI applications involve the interaction of multiple autonomous agents, requiring those agents to reason about their own beliefs, as well as those of other agents. However, planning involving nested beliefs is known to be computationally challenging. In this work, we address the task of synthesizing plans that necessitate reasoning about the beliefs of other agents. We plan from the perspective of a single agent with the potential for goals and actions that involve nested beliefs, non-homogeneous agents, co-present observations, and the ability for one agent to reason as if it were another. We formally characterize our notion of planning with nested belief, and subsequently demonstrate how to automatically convert such problems into problems that appeal to classical planning technology. Our approach represents an important first step towards applying the well-established field of automated planning to the challenging task of planning involving nested beliefs of multiple agents.