7 research outputs found
Learning from Multiple Outlooks
We propose a novel problem formulation of learning a single task when the
data are provided in different feature spaces. Each such space is called an
outlook, and is assumed to contain both labeled and unlabeled data. The
objective is to take advantage of the data from all the outlooks to better
classify each of the outlooks. We devise an algorithm that computes optimal
affine mappings from different outlooks to a target outlook by matching moments
of the empirical distributions. We further derive a probabilistic
interpretation of the resulting algorithm and a sample complexity bound
indicating how many samples are needed to adequately find the mapping. We
report the results of extensive experiments on activity recognition tasks that
show the value of the proposed approach in boosting performance.Comment: with full proofs of theorems and all experiment
Effective Discriminative Feature Selection with Non-trivial Solutions
Feature selection and feature transformation, the two main ways to reduce
dimensionality, are often presented separately. In this paper, a feature
selection method is proposed by combining the popular transformation based
dimensionality reduction method Linear Discriminant Analysis (LDA) and sparsity
regularization. We impose row sparsity on the transformation matrix of LDA
through -norm regularization to achieve feature selection, and
the resultant formulation optimizes for selecting the most discriminative
features and removing the redundant ones simultaneously. The formulation is
extended to the -norm regularized case: which is more likely to
offer better sparsity when . Thus the formulation is a better
approximation to the feature selection problem. An efficient algorithm is
developed to solve the -norm based optimization problem and it is
proved that the algorithm converges when . Systematical experiments
are conducted to understand the work of the proposed method. Promising
experimental results on various types of real-world data sets demonstrate the
effectiveness of our algorithm
Correlative Channel-Aware Fusion for Multi-View Time Series Classification
Multi-view time series classification (MVTSC) aims to improve the performance
by fusing the distinctive temporal information from multiple views. Existing
methods mainly focus on fusing multi-view information at an early stage, e.g.,
by learning a common feature subspace among multiple views. However, these
early fusion methods may not fully exploit the unique temporal patterns of each
view in complicated time series. Moreover, the label correlations of multiple
views, which are critical to boost-ing, are usually under-explored for the
MVTSC problem. To address the aforementioned issues, we propose a Correlative
Channel-Aware Fusion (C2AF) network. First, C2AF extracts comprehensive and
robust temporal patterns by a two-stream structured encoder for each view, and
captures the intra-view and inter-view label correlations with a graph-based
correlation matrix. Second, a channel-aware learnable fusion mechanism is
implemented through convolutional neural networks to further explore the global
correlative patterns. These two steps are trained end-to-end in the proposed
C2AF network. Extensive experimental results on three real-world datasets
demonstrate the superiority of our approach over the state-of-the-art methods.
A detailed ablation study is also provided to show the effectiveness of each
model component
Tensor Canonical Correlation Analysis for Multi-View Dimension Reduction
© 2015 IEEE. Canonical correlation analysis (CCA) has proven an effective tool for two-view dimension reduction due to its profound theoretical foundation and success in practical applications. In respect of multi-view learning, however, it is limited by its capability of only handling data represented by two-view features, while in many real-world applications, the number of views is frequently many more. Although the ad hoc way of simultaneously exploring all possible pairs of features can numerically deal with multi-view data, it ignores the high order statistics (correlation information) which can only be discovered by simultaneously exploring all features. Therefore, in this work, we develop tensor CCA (TCCA) which straightforwardly yet naturally generalizes CCA to handle the data of an arbitrary number of views by analyzing the covariance tensor of the different views. TCCA aims to directly maximize the canonical correlation of multiple (more than two) views. Crucially, we prove that the main problem of multi-view canonical correlation maximization is equivalent to finding the best rank-1 approximation of the data covariance tensor, which can be solved efficiently using the well-known alternating least squares (ALS) algorithm. As a consequence, the high order correlation information contained in the different views is explored and thus a more reliable common subspace shared by all features can be obtained. In addition, a non-linear extension of TCCA is presented. Experiments on various challenge tasks, including large scale biometric structure prediction, internet advertisement classification, and web image annotation, demonstrate the effectiveness of the proposed method