Asia
Fast Algorithm for Non-Stationary Gaussian Process Prediction
Zhang, Yulai (Tsinghua University) | Luo, Guiming (Tsinghua University)
Algorithm's time complexity is an essential issue for time series prediction in numerous practices.A novel fast exact inference method for Gaussian process model is proposed in this paper to accelerate the task of non-stationary time series prediction. Experiment was done on the real world power load data.
Adaptive Multi-Compositionality for Recursive Neural Models with Applications to Sentiment Analysis
Dong, Li (Beihang University) | Wei, Furu (Microsoft Research) | Zhou, Ming (Microsoft Research) | Xu, Ke (Beihang University)
Recursive neural models have achieved promising results in many natural language processing tasks. The main difference among these models lies in the composition function, i.e., how to obtain the vector representation for a phrase or sentence using the representations of words it contains. This paper introduces a novel Adaptive Multi-Compositionality (AdaMC) layer to recursive neural models. The basic idea is to use more than one composition functions and adaptively select them depending on the input vectors. We present a general framework to model each semantic composition as a distribution over these composition functions. The composition functions and parameters used for adaptive selection are learned jointly from data. We integrate AdaMC into existing recursive neural models and conduct extensive experiments on the Stanford Sentiment Treebank. The results illustrate that AdaMC significantly outperforms state-of-the-art sentiment classification methods. It helps push the best accuracy of sentence-level negative/positive classification from 85.4% up to 88.5%.
Robust Multi-View Spectral Clustering via Low-Rank and Sparse Decomposition
Xia, Rongkai (Sun Yat-sen University) | Pan, Yan (Sun Yat-sen University) | Du, Lei (Sun Yat-sen University) | Yin, Jian (Sun Yat-sen University)
Multi-view clustering, which seeks a partition of the data inmultiple views that often provide complementary information to eachother, has received considerable attention in recent years. In reallife clustering problems, the data in each view may haveconsiderable noise. However, existing clustering methods blindlycombine the information from multi-view data with possiblyconsiderable noise, which often degrades their performance. In thispaper, we propose a novel Markov chain method for RobustMulti-view Spectral Clustering (RMSC). Our method has a flavor oflow-rank and sparse decomposition, where we firstly construct atransition probability matrix from each single view, and then usethese matrices to recover a shared low-rank transition probabilitymatrix as a crucial input to the standard Markov chain methodfor clustering. The optimization problem of RMSC has a low-rankconstraint on the transition probability matrix, and simultaneouslya probabilistic simplex constraint on each of its rows. To solvethis challenging optimization problem, we propose an optimization procedurebased on the Augmented Lagrangian Multiplier scheme. Experimentalresults on various real world datasets show that theproposed method has superior performance over severalstate-of-the-art methods for multi-view clustering.
Backdoors into Heterogeneous Classes of SAT and CSP
Gaspers, Serge (University of New South Wales) | Misra, Neeldhara (Indian Institute of Science, Bangalore) | Ordyniak, Sebastian (Masaryk University) | Szeider, Stefan (Vienna University of Technology) | Zivny, Stanislav (University of Oxford)
Backdoor sets represent clever reasoning shortcuts through the search space for SAT and CSP. By instantiating the backdoor variables one reduces the given instance to several easy instances that belong to a tractable class.The overall time needed to solve the instance is exponential in the size of the backdoor set, hence it is a challenging problem to find a small backdoor set if one exists; over the last years this problem has been subject of intensive research. In this paper we extend the classical notion of a strong backdoor set by allowing that different instantiations of the backdoor variables result in instances that belong to different base classes; the union of the base classes forms a heterogeneous base class. Backdoor sets to heterogeneous base classes can be much smaller than backdoor sets to homogeneous ones, hence they are much more desirable but possibly harder to find. We draw a detailed complexity landscape for the problem of detecting strong backdoor sets into heterogeneous base classes for SAT and CSP. We provide algorithms that establish fixed-parameter tractability under natural parameterizations, and we contrast the tractability results with hardness results that pinpoint the theoretical limits. Our results apply to the current state-of-the-art of tractable classes of CSP and SAT that are definable by restricting the constraint language.
Sample-adaptive Multiple Kernel Learning
Liu, Xinwang (National University of Defense Technology, Changsha) | Wang, Lei (University of Wollongong) | Zhang, Jian (University of Technology Sydney) | Yin, Jianping (National University Defense Technology, Changsha)
Existing multiple kernel learning (MKL) algorithms \textit{indiscriminately} apply a same set of kernel combination weights to all samples. However, the utility of base kernels could vary across samples and a base kernel useful for one sample could become noisy for another. In this case, rigidly applying a same set of kernel combination weights could adversely affect the learning performance. To improve this situation, we propose a sample-adaptive MKL algorithm, in which base kernels are allowed to be adaptively switched on/off with respect to each sample. We achieve this goal by assigning a latent binary variable to each base kernel when it is applied to a sample. The kernel combination weights and the latent variables are jointly optimized via margin maximization principle. As demonstrated on five benchmark data sets, the proposed algorithm consistently outperforms the comparable ones in the literature.
Efficient Generalized Fused Lasso and its Application to the Diagnosis of Alzheimer’s Disease
Xin, Bo (Peking University) | Kawahara, Yoshinobu (Osaka University) | Wang, Yizhou (Peking University) | Gao, Wen (Peking University)
Generalized fused lasso (GFL) penalizes variables with L1 norms based both on the variables and their pairwise differences. GFL is useful when applied to data where prior information is expressed using a graph over the variables. However, the existing GFL algorithms incur high computational costs and they do not scale to high-dimensional problems. In this study, we propose a fast and scalable algorithm for GFL. Based on the fact that fusion penalty is the Lov'asz extension of a cut function, we show that the key building block of the optimization is equivalent to recursively solving parametric graph-cut problems. Thus, we use a parametric flow algorithm to solve GFL in an efficient manner. Runtime comparisons demonstrated a significant speed-up compared with the existing GFL algorithms. By exploiting the scalability of the proposed algorithm, we formulated the diagnosis of Alzheimer's disease as GFL. Our experimental evaluations demonstrated that the diagnosis performance was promising and that the selected critical voxels were well structured i.e., connected, consistent according to cross-validation and in agreement with prior clinical knowledge.
Coordination of Multiple Teams of Robots for an Optimal Global Plan
Saribatur, Zeynep Gozen (Sabanci University) | Erdem, Esra (Sabanci University) | Patoglu, Volkan (Sabanci University)
Also, we do many application domains, ranging from search and rescue not assume that all teams are in the same workspace, or all operations to exploration missions, service robotics to cognitive robots are of the same sort. Moreover, our goal is not to find factories. In these domains, the goal is for all teams any coordination of teams that would allow decoupling of to complete their tasks as soon as possible, and should the their local plans, but to find a coordination of teams for an need arise, teams help each other by lending robots.
Lifetime Lexical Variation in Social Media
Liao, Lizi (Beijing Institute of Technology) | Jiang, Jing (Singapore Management University) | Ding, Ying (Singapore Management University) | Huang, Heyan (Beijing Institute of Technology) | Lim, Ee-Peng (Singapore Management University)
As the rapid growth of online social media attracts a large number of Internet users, the large volume of content generated by these users also provides us with an opportunity to study the lexical variation of people of different ages. In this paper, we present a latent variable model that jointly models the lexical content of tweets and Twitter users’ ages. Our model inherently assumes that a topic has not only a word distribution but also an age distribution. We propose a Gibbs-EM algorithm to perform inference on our model. Empirical evaluation shows that our model can learn meaningful age-specific topics such as “school” for teenagers and “health” for older people. Our model can also be used for age prediction and performs better than a number of baseline methods.
Small-Variance Asymptotics for Dirichlet Process Mixtures of SVMs
Wang, Yining (Tsinghua University) | Zhu, Jun (Tsinghua University)
Infinite SVM (iSVM) is a Dirichlet process (DP) mixture of large-margin classifiers. Though flexible in learning nonlinear classifiers and discovering latent clustering structures, iSVM has a difficult inference task and existing methods could hinder its applicability to large-scale problems. This paper presents a small-variance asymptotic analysis to derive a simple and efficient algorithm, which monotonically optimizes a max-margin DP-means (M2DPM) problem, an extension of DP-means for both predictive learning and descriptive clustering. Our analysis is built on Gibbs infinite SVMs, an alternative DP mixture of large-margin machines, which admits a partially collapsed Gibbs sampler without truncation by exploring data augmentation techniques. Experimental results show that M2DPM runs much faster than similar algorithms without sacrificing prediction accuracies.