Technology
Scalable Discriminative Learning for Natural Language Parsing and Translation
Turian, Joseph, Wellington, Benjamin, Melamed, I. D.
Parsing and translating natural languages can be viewed as problems of predicting treestructures. For machine learning approaches to these predictions, the diversity and high dimensionality of the structures involved mandate very large training sets. This paper presents a purely discriminative learning method that scales up well to problems of this size. Its accuracy was at least as good as other comparable methods on a standard parsing task. To our knowledge, it is the first purely discriminative learning algorithm for translation with treestructured models.Unlike other popular methods, this method does not require a great deal of feature engineering a priori, because it performs feature selection overa compound feature space as it learns. Experiments demonstrate the method's versatility, accuracy, and efficiency. Relevant software is freely available at http://nlp.cs.nyu.edu/parser and http://nlp.cs.nyu.edu/GenPar.
Large-Scale Sparsified Manifold Regularization
Tsang, Ivor W., Kwok, James T.
Semi-supervised learning is more powerful than supervised learning by using both labeled and unlabeled data. In particular, the manifold regularization framework, together with kernel methods, leads to the Laplacian SVM (LapSVM) that has demonstrated state-of-the-art performance. However, the LapSVM solution typically involveskernel expansions of all the labeled and unlabeled examples, and is slow on testing. Moreover, existing semi-supervised learning methods, including theLapSVM, can only handle a small number of unlabeled examples. In this paper, we integrate manifold regularization with the core vector machine, which has been used for large-scale supervised and unsupervised learning. By using a sparsified manifold regularizer and formulating as a center-constrained minimum enclosing ball problem, the proposed method produces sparse solutions with low time and space complexities. Experimental results show that it is much faster than the LapSVM, and can handle a million unlabeled examples on a standard PC; while the LapSVM can only handle several thousand patterns.
Learning Motion Style Synthesis from Perceptual Observations
Torresani, Lorenzo, Hackney, Peggy, Bregler, Christoph
This paper presents an algorithm for synthesis of human motion in specified styles. We use a theory of movement observation (Laban Movement Analysis) to describe movement styles as points in a multidimensional perceptual space. We cast the task of learning to synthesize desired movement styles as a regression problem: sequences generated via space-time interpolation of motion capture data are used to learn a nonlinear mapping between animation parameters and movement styles in perceptual space. We demonstrate that the learned model can apply a variety of motion styles to prerecorded motion sequences and it can extrapolate styles not originally included in the training data.
Towards a general independent subspace analysis
The increasingly popular independent component analysis (ICA) may only be applied todata following the generative ICA model in order to guarantee algorithmindependent andtheoretically valid results. Subspace ICA models generalize the assumption of component independence to independence between groups of components. Theyare attractive candidates for dimensionality reduction methods, however are currently limited by the assumption of equal group sizes or less general semi-parametricmodels. By introducing the concept of irreducible independent subspacesor components, we present a generalization to a parameter-free mixture model. Moreover, we relieve the condition of at-most-one-Gaussian by including previous results on non-Gaussian component analysis. After introducing thisgeneral model, we discuss joint block diagonalization with unknown block sizes, on which we base a simple extension of JADE to algorithmically perform the subspace analysis. Simulations confirm the feasibility of the algorithm.
A Collapsed Variational Bayesian Inference Algorithm for Latent Dirichlet Allocation
Teh, Yee W., Newman, David, Welling, Max
Latent Dirichlet allocation (LDA) is a Bayesian network that has recently gained much popularity in applications ranging from document modeling to computer vision. Due to the large scale nature of these applications, current inference procedures like variational Bayes and Gibbs sampling have been found lacking. In this paper we propose the collapsed variational Bayesian inference algorithm for LDA, and show that it is computationally efficient, easy to implement and significantly more accurate than standard variational Bayesian inference for LDA.