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Languages for Learning and Mining
However, it is well-known that applying machine learning and data mining to novel data sets is Finally, inspired by the field of constraint programming, challenging because each application imposes its own requirements (Guns et al. 2013) aim at developing declarative modeling and constraints that often require the development languages for specifying a wide range of mining problems. of new algorithms and systems. While there are software Such languages should support packages and tools such as Scikit for machine learning the high-level and natural modeling of pattern mining and Weka, Orange or Knime for data mining, adapting them tasks; that is, the models should closely correspond to to novel tasks is not easy, which explains why one often resorts the definitions of data mining problems found in the to implementing new algorithms and variations from literature; should support user-defined constraints and scratch.
SAT Modulo Monotonic Theories
Bayless, Sam (University of British Columbia) | Bayless, Noah (Point Grey Mini Secondary School) | Hoos, Holger H. (University of British Columbia) | Hu, Alan J. (University of British Columbia)
Boolean satisfiability (SAT) solvers have been successfully applied to a wide variety of difficult combinatorial problems. Many further problems can be solved by SAT Modulo Theory (SMT) solvers, which extend SAT solvers to handle additional types of constraints. However, building efficient SMT solvers is often very difficult. In this paper, we define the concept of a Boolean monotonic theory and show how to easily build efficient SMT solvers, including effective theory propagation and clause learning, for such theories. We present examples showing useful constraints that are monotonic, including many graph properties (e.g., shortest paths), and geometric properties (e.g., convex hulls). These constraints arise in problems that are otherwise difficult for SAT solvers to handle, such as procedural content generation. We have implemented several monotonic theory solvers using the techniques we present in this paper and applied these to content generation problems, demonstrating major speed-ups over SAT, SMT, and Answer Set Programming solvers, easily solving instances that were previously out of reach.
Noise-Robust Semi-Supervised Learning by Large-Scale Sparse Coding
Lu, Zhiwu (Renmin University of China) | Gao, Xin (King Abdullah University of Science and Technology) | Wang, Liwei (Peking University) | Wen, Ji-Rong (Renmin University of China) | Huang, Songfang (IBM China Research Lab)
This paper presents a large-scale sparse coding algorithm to deal with the challenging problem of noise-robust semi-supervised learning over very large data with only few noisy initial labels. By giving an L1-norm formulation of Laplacian regularization directly based upon the manifold structure of the data, we transform noise-robust semi-supervised learning into a generalized sparse coding problem so that noise reduction can be imposed upon the noisy initial labels. Furthermore, to keep the scalability of noise-robust semi-supervised learning over very large data, we make use of both nonlinear approximation and dimension reduction techniques to solve this generalized sparse coding problem in linear time and space complexity. Finally, we evaluate the proposed algorithm in the challenging task of large-scale semi-supervised image classification with only few noisy initial labels. The experimental results on several benchmark image datasets show the promising performance of the proposed algorithm.
Effect of Spatial Pooler Initialization on Column Activity in Hierarchical Temporal Memory
Leake, Mackenzie (Scripps College) | Xia, Liyu (University of Chicago) | Rocki, Kamil (IBM Research) | Imaino, Wayne (IBM Research)
In the Hierarchical Temporal Memory (HTM) paradigm the effect of overlap between inputs on the activation of columns in the spatial pooler is studied. Numerical results suggest that similar inputs are represented by similar sets of columns and dissimilar inputs are represented by dissimilar sets of columns. It is shown that the spatial pooler produces these results under certain conditions for the connectivity and proximal thresholds at initialization. Qualitative arguments about the learning dynamics of the spatial pooler are then discussed.
Multi-Objective Reinforcement Learning with Continuous Pareto Frontier Approximation
Pirotta, Matteo (Politecnico di Milano) | Parisi, Simone (Politecnico di Milano) | Restelli, Marcello (Politecnico di Milano)
This paper is about learning a continuous approximation of the Pareto frontier in Multi-Objective Markov Decision Problems (MOMDPs).We propose a policy-based approach that exploits gradient information to generate solutions close to the Pareto ones.Differently from previous policy-gradient multi-objective algorithms, where n optimization routines are used to have n solutions, our approach performs a single gradient-ascent run that at each step generates an improved continuous approximation of the Pareto frontier.The idea is to exploit a gradient-based approach to optimize the parameters of a function that defines a manifold in the policy parameter space so that the corresponding image in the objective space gets as close as possible to the Pareto frontier.Besides deriving how to compute and estimate such gradient, we will also discuss the non-trivial issue of defining a metric to assess the quality of the candidate Pareto frontiers.Finally, the properties of the proposed approach are empirically evaluated on two interesting MOMDPs.
Sense-Aaware Semantic Analysis: A Multi-Prototype Word Representation Model Using Wikipedia
Wu, Zhaohui (The Pennsylvania State University) | Giles, C. Lee (The Pennsylvania State University)
Human languages are naturally ambiguous, which makes it difficult to automatically understand the semantics of text. Most vector space models (VSM) treat all occurrences of a word as the same and build a single vector to represent the meaning of a word, which fails to capture any ambiguity. We present sense-aware semantic analysis (SaSA), a multi-prototype VSM for word representation based on Wikipedia, which could account for homonymy and polysemy. The "sense-specific'' prototypes of a word are produced by clustering Wikipedia pages based on both local and global contexts of the word in Wikipedia. Experimental evaluations on semantic relatedness for both isolated words and words in sentential contexts and word sense induction demonstrate its effectiveness.
Emerging Architectures for Global System Science
Milano, Michela (Universita') | Hentenryck, Pascal Van (di Bologna)
Our society is organized around a number of (interdependent) global systems. Logistic and supply chains, health services, energy networks, financial markets, computer networks, and cities are just a few examples of such global, complex systems. These global systems are socio-technical and involve interactions between complex infrastructures, man-made processes, natural phenomena, multiple stakeholders, and human behavior. For the first time in the history of manking, we have access to data sets of unprecedented scale and accuracy about these infrastructures, processes, natural phenomena, and human behaviors. In addition, progress in high-performancing computing, data mining, machine learning, and decision support opens the possibility of looking at these problems more holistically, capturing many of these aspects simultaneously. This paper addresses emergent architectures enabling controlling, predicting and reaoning on these systems.
Large Margin Metric Learning for Multi-Label Prediction
Liu, Weiwei (University of Technology, Sydney) | Tsang, Ivor W (University of Technology, Sydney)
Canonical correlation analysis (CCA) and maximum margin output coding (MMOC) methods have shown promising results for multi-label prediction, where each instance is associated with multiple labels. However, these methods require an expensive decoding procedure to recover the multiple labels of each testing instance. The testing complexity becomes unacceptable when there are many labels. To avoid decoding completely, we present a novel large margin metric learning paradigm for multi-label prediction. In particular, the proposed method learns a distance metric to discover label dependency such that instances with very different multiple labels will be moved far away. To handle many labels, we present an accelerated proximal gradient procedure to speed up the learning process. Comprehensive experiments demonstrate that our proposed method is significantly faster than CCA and MMOC in terms of both training and testing complexities. Moreover, our method achieves superior prediction performance compared with state-of-the-art methods.
Multi-tensor Completion with Common Structures
Li, Chao (Harbin Engineering University) | Zhao, Qibin (Riken) | Li, Junhua (Riken) | Cichocki, Andrzej (Riken) | Guo, Lili (Harbin Engineering University)
In multi-data learning, it is usually assumed that common latent factors exist among multi-datasets, but it may lead to deteriorated performance when datasets are heterogeneous and unbalanced. In this paper, we propose a novel common structure for multi-data learning. Instead of common latent factors, we assume that datasets share Common Adjacency Graph (CAG) structure, which is more robust to heterogeneity and unbalance of datasets. Furthermore, we utilize CAG structure to develop a new method for multi-tensor completion, which exploits the common structure in datasets to improve the completion performance. Numerical results demostrate that the proposed method not only outperforms state-of-the-art methods for video in-painting, but also can recover missing data well even in cases that conventional methods are not applicable.
Support Consistency of Direct Sparse-Change Learning in Markov Networks
Liu, Song (Tokyo Institute of Technology, Japan) | Suzuki, Taiji (Tokyo Institute of Technology, Japan) | Sugiyama, Masashi (University of Tokyo, Japan)
We study the problem of learning sparse structure changes between two Markov networks P and Q. Rather than fitting two Markov networks separately to two sets of data and figuring out their differences, a recent work proposed to learn changes directly via estimating the ratio between two Markov network models. Such a direct approach was demonstrated to perform excellently in experiments, although its theoretical properties remained unexplored. In this paper, we give sufficient conditions for successful change detection with respect to the sample size np, nq, the dimension of data m, and the number of changed edges d.