Multi-label classification exhibits several challenges not present in the binary case. The labels may be interdependent, so that the presence of a certain label affects the probability of other labels' presence. Thus, exploiting dependencies among the labels could be beneficial for the classifier's predictive performance. Surprisingly, only a few of the existing algorithms address this issue directly by identifying dependent labels explicitly from the dataset. In this paper we propose new approaches for identifying and modeling existing dependencies between labels. One principal contribution of this work is a theoretical confirmation of the reduction in sample complexity that is gained from unconditional dependence. Additionally, we develop methods for identifying conditionally and unconditionally dependent label pairs; clustering them into several mutually exclusive subsets; and finally, performing multi-label classification incorporating the discovered dependencies. We compare these two notions of label dependence (conditional and unconditional) and evaluate their performance on various benchmark and artificial datasets. We also compare and analyze labels identified as dependent by each of the methods. Moreover, we define an ensemble framework for the new methods and compare it to existing ensemble methods. An empirical comparison of the new approaches to existing base-line and state-of-the-art methods on 12 various benchmark datasets demonstrates that in many cases the proposed single-classifier and ensemble methods outperform many multi-label classification algorithms. Perhaps surprisingly , we discover that the weaker notion of unconditional dependence plays the decisive role.
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Dependencies between the labels are commonly regarded as the crucial issue in multi-label classification. Rules provide a natural way for symbolically describing such relationships. For instance, rules with label tests in the body allow for representing directed dependencies like implications, subsumptions, or exclusions. Moreover, rules naturally allow to jointly capture both local and global label dependencies. In this paper, we introduce two approaches for learning such label-dependent rules. Our first solution is a bootstrapped stacking approach which can be built on top of a conventional rule learning algorithm. For this, we learn for each label a separate ruleset, but we include the remaining labels as additional attributes in the training instances. The second approach goes one step further by adapting the commonly used separate-and-conquer algorithm for learning multi-label rules. The main idea is to re-include the covered examples with the predicted labels so that this information can be used for learning subsequent rules. Both approaches allow for making label dependencies explicit in the rules. In addition, the usage of standard rule learning techniques targeted at producing accurate predictions ensures that the found rules are useful for actual classification. Our experiments show (a) that the discovered dependencies contribute to the understanding and improve the analysis of multi-label datasets, and (b) that the found multi-label rules are crucial for the predictive performance as our proposed approaches beat the baseline using conventional rules.
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The automated categorization (or classification) of texts into predefinedcategories has witnessed a booming interest in the last ten years, due to theincreased availability of documents in digital form and the ensuing need toorganize them. In the research community the dominant approach to this problemis based on machine learning techniques: a general inductive processautomatically builds a classifier by learning, from a set of preclassifieddocuments, the characteristics of the categories. The advantages of thisapproach over the knowledge engineering approach (consisting in the manualdefinition of a classifier by domain experts) are a very good effectiveness,considerable savings in terms of expert manpower, and straightforwardportability to different domains. This survey discusses the main approaches totext categorization that fall within the machine learning paradigm. We willdiscuss in detail issues pertaining to three different problems, namelydocument representation, classifier construction, and classifier evaluation.
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Multi-label learning has received significant attention in the research community over the past few years: this has resulted in the development of a variety of multi-label learning methods. In this paper, we present an extensive experimental comparison of 12 multi-label learning methods using 16 evaluation measures over 11 benchmark datasets. We selected the competing methods based on their previous usage by the community, the representation of different groups of methods and the variety of basic underlying machine learning methods. Similarly, we selected the evaluation measures to be able to assess the behavior of the methods from a variety of viewpoints. In order to make conclusions independent from the application domain, we use 11 datasets from different domains. Furthermore, we compare the methods by their efficiency in terms of time needed to learn a classifier and time needed to produce a prediction for an unseen example. We analyze the results from the experiments using Friedman and Nemenyi tests for assessing the statistical significance of differences in performance. The results of the analysis show that for multi-label classification the best performing methods overall are random forests of predictive clustering trees (RF-PCT) and hierarchy of multi-label classifiers (HOMER), followed by binary relevance (BR) and classifier chains (CC). Furthermore, RF-PCT exhibited the best performance according to all measures for multi-label ranking. The recommendation from this study is that when new methods for multi-label learning are proposed, they should be compared to RF-PCT and HOMER using multiple evaluation measures.
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This paper presents the top 10 data mining algorithms identified by the IEEE International Conference on Data Mining (ICDM) in December 2006: C4.5, k-Means, SVM, Apriori, EM, PageRank, AdaBoost, kNN, Naive Bayes, and CART. These top 10 algorithms are among the most influential data mining algorithms in the research community. With each algorithm, we provide a description of the algorithm, discuss the impact of the algorithm, and review current and further research on the algorithm. These 10 algorithms cover classification,
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In this dissertation, the problem of learning from highly imbalanced data is studied. Imbalance data learning is of great importance and challenge in many real applications. Dealing with a minority class normally needs new concepts, observations and solutions in order to fully understand the underlying complicated models. We try to systematically review and solve this special learning task in this dis-sertation. We propose a new ensemble learning framework-Diversified Ensemble Classifiers for Imbal-anced Data Learning (DECIDL), based on the advantages of existing ensemble imbalanced learning strategies. Our framework combines three learning techniques: a) ensemble learning, b) artificial example generation, and c) diversity construction by reversely data re-labeling. As a meta-learner, DECIDL utilizes general supervised learning algorithms as base learners to build an ensemble committee. We create a standard benchmark data pool, which contains 30 highly skewed sets with diverse characteristics from different domains, in order to facilitate future research on imbalance data learning. We use this benchmark pool to evaluate and compare our DECIDL framework with several ensemble learning methods, namely under-bagging, over-bagging, SMOTE-bagging, and AdaBoost. Extensive experiments suggest that our DECIDL framework is comparable with other methods. The data sets, experiments and results provide a valuable knowledge base for future research on imbalance learning. We develop a simple but effective artificial example generation method for data balancing. Two new methods DBEG-ensemble and DECIDL-DBEG are then designed to improve the power of imbalance learning. Experiments show that these two methods are comparable to the state-of-the-art methods, e.g., GSVM-RU and SMOTE-bagging. Furthermore, we investigate learning on imbalanced data from a new angle-active learning. By combining active learning with the DECIDL framework, we show that the newly designed Active-DECIDL method is very effective for imbalance learning, suggesting the DECIDL framework is very robust and flexible. Lastly, we apply the proposed learning methods to a real-world bioinformatics problem-protein methylation prediction. Extensive computational results show that the DECIDL method does perform very well for the imbalanced data mining task. Importantly, the experimental results have confirmed our new contributions on this particular data learning problem. iv DEDICATION To my parents, To my grandfather, who cherished me since a kid, To my grandmother, who loved me the most, but I don't know her name, To my love. v ACKNOWLEDGEMENTS
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We are honored to welcome you to the 2nd International Workshop on Advanced Analyt-ics and Learning on Temporal Data (AALTD), which is held in Riva del Garda, Italy, on September 19th, 2016, co-located with The European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML/PKDD 2016). The aim of this workshop is to bring together researchers and experts in machine learning, data mining, pattern analysis and statistics to share their challenging issues and advance researches on temporal data analysis. Analysis and learning from temporal data cover a wide scope of tasks including learning metrics, learning representations, unsupervised feature extraction, clustering and classification. This volume contains the conference program, an abstract of the invited keynotes and the set of regular papers accepted to be presented at the conference. Each of the submitted papers was reviewed by at least two independent reviewers, leading to the selection of eleven papers accepted for presentation and inclusion into the program and these proceedings. The contributions are given by the alphabetical order, by surname. The keynote given by Marco Cuturi on "Regularized DTW Divergences for Time Se-ries" focuses on the definition of alignment kernels for time series that can later be used at the core of standard machine learning algorithms. The one given by Tony Bagnall on "The Great Time Series Classification Bake Off" presents an important attempt to experimentally compare performance of a wide range of time series classifiers, together with ensemble classifiers that aim at combining existing classifiers to improve classification quality. Accepted papers spanned from innovative ideas on analytic of temporal data, including promising new approaches and covering both practical and theoretical issues. We wish to thank the ECML PKDD council members for giving us the opportunity to hold the AALTD workshop within the framework of the ECML/PKDD Conference and the members of the local organizing committee for their support. The organizers of the AALTD conference gratefully thank the financial support of the Université de Rennes 2, MODES and Universidade da Coruña. Last but not least, we wish to thank the contributing authors for the high quality works and all members of the Reviewing Committee for their invaluable assistance in the iii selection process. All of them have significantly contributed to the success of AALTD 2106. We sincerely hope that the workshop participants have a great and fruitful time at the conference.
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We are honored to welcome you to the 2nd International Workshop on Advanced Analyt-ics and Learning on Temporal Data (AALTD), which is held in Riva del Garda, Italy, on September 19th, 2016, co-located with The European Conference on Machine Learning and Principles and Practice of Knowledge Discovery in Databases (ECML/PKDD 2016). The aim of this workshop is to bring together researchers and experts in machine learning, data mining, pattern analysis and statistics to share their challenging issues and advance researches on temporal data analysis. Analysis and learning from temporal data cover a wide scope of tasks including learning metrics, learning representations, unsupervised feature extraction, clustering and classification. This volume contains the conference program, an abstract of the invited keynotes and the set of regular papers accepted to be presented at the conference. Each of the submitted papers was reviewed by at least two independent reviewers, leading to the selection of eleven papers accepted for presentation and inclusion into the program and these proceedings. The contributions are given by the alphabetical order, by surname. The keynote given by Marco Cuturi on "Regularized DTW Divergences for Time Se-ries" focuses on the definition of alignment kernels for time series that can later be used at the core of standard machine learning algorithms. The one given by Tony Bagnall on "The Great Time Series Classification Bake Off" presents an important attempt to experimentally compare performance of a wide range of time series classifiers, together with ensemble classifiers that aim at combining existing classifiers to improve classification quality. Accepted papers spanned from innovative ideas on analytic of temporal data, including promising new approaches and covering both practical and theoretical issues. We wish to thank the ECML PKDD council members for giving us the opportunity to hold the AALTD workshop within the framework of the ECML/PKDD Conference and the members of the local organizing committee for their support. The organizers of the AALTD conference gratefully thank the financial support of the Université de Rennes 2, MODES and Universidade da Coruña. Last but not least, we wish to thank the contributing authors for the high quality works and all members of the Reviewing Committee for their invaluable assistance in the iii selection process. All of them have significantly contributed to the success of AALTD 2106. We sincerely hope that the workshop participants have a great and fruitful time at the conference.
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Multi-label learning studies the problem where each example is represented by a single instance while associated with a set of labels simultaneously. During the past decade, significant amount of progresses have been made toward this emerging machine learning paradigm. This paper aims to provide a timely review on this area with emphasis on state-of-the-art multi-label learning algorithms. Firstly, fundamentals on multi-label learning including formal definition and evaluation metrics are given. Secondly and primarily, eight representative multi-label learning algorithms are scrutinized under common notations with relevant analyses and discussions. Thirdly, several related learning settings are briefly summarized. As a conclusion, online resources and open research problems on multi-label learning are outlined for reference purposes.
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The F-measure, which has originally been introduced in information retrieval, is nowadays routinely used as a performance metric for problems such as binary classification, multi-label classification, and structured output prediction. Optimizing this measure is a statistically and computationally challenging problem, since no closed-form solution exists. Adopting a decision-theoretic perspective, this article provides a formal and experimental analysis of different approaches for maximizing the F-measure. We start with a Bayes-risk analysis of related loss functions, such as Hamming loss and subset zero-one loss, showing that optimizing such losses as a surrogate of the F-measure leads to a high worst-case regret. Subsequently, we perform a similar type of analysis for F-measure maximizing algorithms , showing that such algorithms are approximate, while relying on additional assumptions regarding the statistical distribution of the binary response variables. Furthermore, we present a new algorithm which is not only computationally efficient but also Bayes-optimal, regardless of the underlying distribution. To this end, the algorithm requires only a quadratic (with respect to the number of binary responses) number of parameters of the joint distribution. We illustrate the practical performance of all analyzed methods by means of experiments with multi-label classification problems.
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We introduce a very general method for high dimensional classification, based on careful combination of the results of applying an arbitrary base classifier to random projections of the feature vectors into a lower dimensional space. In one special case that we study in detail, the random projections are divided into disjoint groups, and within each group we select the projection yielding the smallest estimate of the test error. Our random-projection ensemble classifier then aggregates the results of applying the base classifier on the selected projections, with a data-driven voting threshold to determine the final assignment. Our theoretical results elucidate the effect on performance of increasing the number of projections. Moreover, under a boundary condition that is implied by the sufficient dimension reduction assumption, we show that the test excess risk of the random-projection ensemble classifier can be controlled by terms that do not depend on the original data dimension and a term that becomes negligible as the number of projections increases. The classifier is also compared empirically with several other popular high dimensional classifiers via an extensive simulation study, which reveals its excellent finite sample performance.
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Several meta-learning techniques for multi-label classification (MLC), such as chaining and stacking, have already been proposed in the literature, mostly aimed at improving predictive accuracy through the exploitation of label dependencies. In this paper, we propose another technique of that kind, called dependent binary relevance (DBR) learning. DBR combines properties of both, chaining and stacking. We provide a careful analysis of the relationship between these and other techniques, specifically focusing on the underlying dependency structure and the type of training data used for model construction. Moreover, we offer an extensive empirical evaluation, in which we compare different techniques on MLC benchmark data. Our experiments provide evidence for the good performance of DBR in terms of several evaluation measures that are commonly used in MLC.
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The problem of classification has been widely studied in the data mining, machine learning, database, and information retrieval communities with applications in a number of diverse domains, such as target marketing, medical diagnosis, news group filtering, and document organization. In this paper we will provide a survey of a wide variety of text classification algorithms.
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Supervised machine learning is the search for algorithms that reason from externally supplied instances to produce general hypotheses, which then make predictions about future instances. In other words, the goal of supervised learning is to build a concise model of the distribution of class labels in terms of predictor features. The resulting classifier is then used to assign class labels to the testing instances where the values of the predictor features are known, but the value of the class label is unknown. This paper describes various supervised machine learning classification techniques. Of course, a single article cannot be a complete review of all supervised machine learning classification algorithms (also known induction classification algorithms), yet we hope that the references cited will cover the major theoretical issues, guiding the researcher in interesting research directions and suggesting possible bias combinations that have yet to be explored. Povzetek: Podan je pregled metod strojnega učenja.
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In this paper, we address the task of learning models for predicting structured outputs. We consider both global and local predictions of structured outputs, the former based on a single model that predicts the entire output structure and the latter based on a collection of models, each predicting a component of the output structure. We use ensemble methods and apply them in the context of predicting structured outputs. We propose to build ensemble models consisting of predictive clustering trees, which generalize classification trees: these have been used for predicting different types of structured outputs, both locally and globally. More specifically, we develop methods for learning two types of ensembles (bagging and random forests) of predictive clustering trees for global and local predictions of different types of structured outputs. The types of outputs considered correspond to different predictive modeling tasks: multi-target regression, multi-target classification, and hierarchical multi-label classification. Each of the combinations can be applied both in the context of global prediction (producing a single ensemble) or local prediction (producing a collection of ensembles). We conduct an extensive experimental evaluation across a range of benchmark datasets for each of the three types of structured outputs. We compare ensembles for global and local prediction, as well as single trees for global prediction and tree collections for local prediction, both in terms of predictive performance and in terms of efficiency (running times and model complexity). The results show that both global and local tree ensembles perform better than the single model counterparts in terms of predictive power. Global and local tree ensembles perform equally well, with global ensembles being more efficient and producing smaller models, as well as needing fewer trees in the ensemble to achieve the maximal performance.
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多标签分类(MLC)是一种监督学习问题,其中与标准多类分类相反,实例可以同时与多个类标签相关联。在本章中,我们提倡基于arule的多标签分类方法。当人们不仅对准确的预测感兴趣时,还需要使用规则学习算法,但也需要可由域专家理解,分析和定性评估的可解释理论。理想情况下,通过揭示数据中包含的模式和规律性,基于规则的理论在应用领域中产生了新的见解。最近,一些作者开始研究基于规则的模型可以用于建模多标签数据。详细讨论这项任务,我们强调了一些问题,使得规则学习对于MLC而言比传统分类更具挑战性。虽然我们主要关注自己以前的工作,但我们还提供了该领域相关工作的简短视图。
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