In this task, you are given a part of an article. Your task is to generate headline (title) for this text. Preferred headlines are under fifteen words.

Input: Consider Input: Metric learning has been shown to be highly effective to improve the performance of nearest neighbor classification. In this paper, we address the problem of metric learning for symmetric positive definite (SPD) matrices such as covariance matrices, which arise in many real-world applications. Naively using standard Mahalanobis metric learning methods under the Euclidean geometry for SPD matrices is not appropriate, because the difference of SPD matrices can be a non-SPD matrix and thus the obtained solution can be uninterpretable. To cope with this problem, we propose to use a properly parameterized LogEuclidean distance and optimize the metric with respect to kernel-target alignment, which is a supervised criterion for kernel learning. Then the resulting non-trivial optimization problem is solved by utilizing the Riemannian geometry. Finally, we experimentally demonstrate the usefulness of our LogEuclidean metric learning algorithm on real-world classification tasks for EEG signals and texture patches.

Output: Supervised LogEuclidean Metric Learning for Symmetric Positive Definite Matrices


Input: Consider Input: Multitask learning algorithms are typically designed assuming some fixed, a priori known latent structure shared by all the tasks. However, it is usually unclear what type of latent task structure is the most appropriate for a given multitask learning problem. Ideally, the “right” latent task structure should be learned in a data-driven manner. We present a flexible, nonparametric Bayesian model that posits a mixture of factor analyzers structure on the tasks. The nonparametric aspect makes the model expressive enough to subsume many existing models of latent task structures (e.g, meanregularized tasks, clustered tasks, low-rank or linear/non-linear subspace assumption on tasks, etc.). Moreover, it can also learn more general task structures, addressing the shortcomings of such models. We present a variational inference algorithm for our model. Experimental results on synthetic and realworld datasets, on both regression and classification problems, demonstrate the effectiveness of the proposed method.

Output: Flexible Modeling of Latent Task Structures in Multitask Learning


Input: Consider Input: The cascade model is a well-established model of user interaction with content. In this work, we propose cascading bandits, a learning variant of the model where the objective is to learn K most attractive items out of L ground items. We cast the problem as a stochastic combinatorial bandit with a non-linear reward function and partially observed weights of items. Both of these are challenging in the context of combinatorial bandits. We propose two computationally-efficient algorithms for our problem, CascadeUCB1 and CascadeKL-UCB, and prove gap-dependent upper bounds on their regret. We also derive a lower bound for cascading bandits and show that it matches the upper bound of CascadeKL-UCB up to a logarithmic factor. Finally, we evaluate our algorithms on synthetic problems. Our experiments demonstrate that the algorithms perform well and robustly even when our modeling assumptions are violated.


Output: Cascading Bandits