Education
Report on the 22nd International FLAIRS Conference
Guesgen, Hans Werner (Massey University)
The 22nd International Florida Artificial Intelligence Research Society Conference (FLAIRS-22) was held 19th โ 21st May 2009 at the Sundial Beach and Golf Resort on Sanibel Island, Florida, USA.ย It continued a long tradition of FLAIRS conferences, which attract researchers from around the world.ย The conference featured technical papers, special tracks, and invited speakers.ย This yearโs conference was chaired by Susan Haller, from the State University of New York at Potsdam.ย Conference program co-chairs were Hans W. Guesgen, from Massey University in New Zealand, and H. Chad Lane, from the University of Southern California.ย The special tracks were coordinated by Philip McCarthy, from the University of Memphis.
Slow Learners are Fast
Zinkevich, Martin, Langford, John, Smola, Alex J.
Online learning algorithms have impressive convergence properties when it comes to risk minimization and convex games on very large problems. However, they are inherently sequential in their design which prevents them from taking advantage of modern multi-core architectures. In this paper we prove that online learning with delayed updates converges well, thereby facilitating parallel online learning.
Translated Learning: Transfer Learning across Different Feature Spaces
Dai, Wenyuan, Chen, Yuqiang, Xue, Gui-rong, Yang, Qiang, Yu, Yong
This paper investigates a new machine learning strategy called translated learning. Unlike many previous learning tasks, we focus on how to use labeled data from one feature space to enhance the classification of other entirely different learning spaces. For example, we might wish to use labeled text data to help learn a model for classifying image data, when the labeled images are difficult to obtain. An important aspect of translated learning is to build a "bridge" to link one feature space (known as the "source space") to another space (known as the "target space") through a translator in order to migrate the knowledge from source to target. The translated learning solution uses a language model to link the class labels to the features in the source spaces, which in turn is translated to the features in the target spaces. Finally, this chain of linkages is completed by tracing back to the instances in the target spaces. We show that this path of linkage can be modeled using a Markov chain and risk minimization. Through experiments on the text-aided image classification and cross-language classification tasks, we demonstrate that our translated learning framework can greatly outperform many state-of-the-art baseline methods.
Translated Learning: Transfer Learning across Different Feature Spaces
Dai, Wenyuan, Chen, Yuqiang, Xue, Gui-rong, Yang, Qiang, Yu, Yong
This paper investigates a new machine learning strategy called translated learning. Unlike many previous learning tasks, we focus on how to use labeled data from one feature space to enhance the classification of other entirely different learning spaces. For example, we might wish to use labeled text data to help learn a model for classifying image data, when the labeled images are difficult to obtain. An important aspect of translated learning is to build a "bridge" to link one feature space (known as the "source space") to another space (known as the "target space") through a translator in order to migrate the knowledge from source to target. The translated learning solution uses a language model to link the class labels to the features in the source spaces, which in turn is translated to the features in the target spaces. Finally, this chain of linkages is completed by tracing back to the instances in the target spaces. We show that this path of linkage can be modeled using a Markov chain and risk minimization. Through experiments on the text-aided image classification and cross-language classification tasks, we demonstrate that our translated learning framework can greatly outperform many state-of-the-art baseline methods.
Nonlinear Learning using Local Coordinate Coding
Yu, Kai, Zhang, Tong, Gong, Yihong
This paper introduces a new method for semi-supervised learning on high dimensional nonlinear manifolds, which includes a phase of unsupervised basis learning and a phase of supervised function learning. The learned bases provide a set of anchor points to form a local coordinate system, such that each data point x on the manifold can be locally approximated by a linear combination of its nearby anchor points, and the linear weights become its local coordinate coding. We show that a high dimensional nonlinear function can be approximated by a global linear function with respect to this coding scheme, and the approximation quality is ensured by the locality of such coding. The method turns a difficult nonlinear learning problem into a simple global linear learning problem, which overcomes some drawbacks of traditional local learning methods.
AUC optimization and the two-sample problem
Vayatis, Nicolas, Depecker, Marine, Clรฉmenรงcon, Stรฉphan J.
The purpose of the paper is to explore the connection between multivariate homogeneity testsand AUC optimization. The latter problem has recently received much attention in the statistical learning literature. From the elementary observation that,in the two-sample problem setup, the null assumption corresponds to the situation where the area under the optimal ROC curve is equal to 1/2, we propose atwo-stage testing method based on data splitting. A nearly optimal scoring function in the AUC sense is first learnt from one of the two half-samples. Data from the remaining half-sample are then projected onto the real line and eventually rankedaccording to the scoring function computed at the first stage. The last step amounts to performing a standard Mann-Whitney Wilcoxon test in the onedimensional framework.We show that the learning step of the procedure does not affect the consistency of the test as well as its properties in terms of power, provided the ranking produced is accurate enough in the AUC sense. The results of a numerical experiment are eventually displayed in order to show the efficiency of the method.
Differential Use of Implicit Negative Evidence in Generative and Discriminative Language Learning
Hsu, Anne, Griffiths, Thomas L.
A classic debate in cognitive science revolves around understanding how children learn complex linguistic rules, such as those governing restrictions on verb alternations, without negative evidence. Traditionally, formal learnability arguments have been used to claim that such learning is impossible without the aid of innate language-specific knowledge. However, recently, researchers have shown that statistical models are capable of learning complex rules from only positive evidence. These two kinds of learnability analyses differ in their assumptions about the role of the distribution from which linguistic input is generated. The former analyses assume that learners seek to identify grammatical sentences in a way that is robust to the distribution from which the sentences are generated, analogous to discriminative approaches in machine learning. The latter assume that learners are trying to estimate a generative model, with sentences being sampled from that model. We show that these two learning approaches differ in their use of implicit negative evidence -- the absence of a sentence -- when learning verb alternations, and demonstrate that human learners can produce results consistent with the predictions of both approaches, depending on the context in which the learning problem is presented.
Regularized Distance Metric Learning:Theory and Algorithm
Jin, Rong, Wang, Shijun, Zhou, Yang
In this paper, we examine the generalization error of regularized distance metric learning. We show that with appropriate constraints, the generalization error of regularized distance metric learning could be independent from the dimensionality, making it suitable for handling high dimensional data. In addition, we present an efficient online learning algorithm for regularized distance metric learning. Our empirical studies with data classification and face recognition show that the proposed algorithm is (i) effective for distance metric learning when compared to the state-of-the-art methods, and (ii) efficient and robust for high dimensional data.
Human Active Learning
Castro, Rui M., Kalish, Charles, Nowak, Robert, Qian, Ruichen, Rogers, Tim, Zhu, Jerry
We investigate a topic at the interface of machine learning and cognitive science. Human active learning, where learners can actively query the world for information, is contrasted with passive learning from random examples. Furthermore, we compare human active learning performance with predictions from statistical learning theory. We conduct a series of human category learning experiments inspired by a machine learning task for which active and passive learning error bounds are well understood, and dramatically distinct. Our results indicate that humans are capable of actively selecting informative queries, and in doing so learn better and faster than if they are given random training data, as predicted by learning theory. However, the improvement over passive learning is not as dramatic as that achieved by machine active learning algorithms. To the best of our knowledge, this is the first quantitative study comparing human category learning in active versus passive settings.