Statistical machine learning for data mining and collaborative multimedia retrieval

Statistical machine learning techniques have been widely applied in data mining and multimedia information retrieval. While traditional methods; such as supervised learning, unsupervised learning, and active learning, have been extensively studied separately, there are few comprehensive schemes to investigate these techniques in a unified approach. This thesis proposes a unified learning paradigm (ULP) framework that integrates several machine learning techniques including supervised learning; unsupervised learning, semi-supervised learning, active learning and metric learning in a synergistic way to maximize the effectiveness of a learning task. Based on this unified learning framework, a novel scheme is suggested for learning Unified Kernel Machines (UKM). The UKM scheme combines supervised kernel machine learning, unsupervised kernel de sign, semi-supervised kernel learning, and active learning in an effective fashion. A key component in the UKM scheme is to learn kernels from both labeled and unlabeled data. To this purpose; a new Spectral Kernel Learning (SKL) algorithm is proposed, which is related to a quadratic program. Empirical results show that the UKM technique is promising for classification tasks. Within the unified learning framework, this thesis further explores two important challenging tasks. One is Batch Mode Active Learning (BMAL). In contrast to traditional approaches, the BMAL method searches a batch of informative examples for labeling. To develop an effective algorithm, the BMAL task is formulated into a convex optimization problem and a novel bound optimization algorithm is proposed to efficiently solve it with global optima. Extensive evaluations on text categorization tasks show that the BMAL algorithm is superior to traditional methods. Another issue studied in the framework is Distance Metric Learning (DML). Learning distance metrics is critical to many machine learning tasks, especially when contextual information is available. To learn effective metrics from pairwise contextual constraints, two novel methods, Discriminative Component Analysis (DCA) and Kernel DCA, are proposed to learn both linear and nonlinear distance metrics. Empirical results on data clustering validate the advantages of the algorithms. In addition to the above methodologies, this thesis also addresses some practical issues in applying machine learning techniques to real-world applications. For example, in a time-dependent data mining application, in order to design a domain-specific kernel, marginalized kernel techniques are suggested to formulate an effective kernel aimed at web data mining tasks. Last, the thesis investigates statistical machine learning techniques with applications to multimedia retrieval and addresses some practical issues, such as robustness to noise and scalability. To bridge semantic gap issues of multimedia retrieval, a Collaborative Multimedia Retrieval (CMR) scheme is proposed to exploit historical log data of users' relevance feedback for improving retrieval tasks. Two types of learning tasks in the CMR scheme are identified and two innovative algorithms are proposed to effectively solve the problems respectively.