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- Ambuj Tewari, Peter L. Bartlett
- Journal of Machine Learning Research
- 2005

Binary classification is a well studied special case of the classification problem. Statistical properties of binary classifiers, such as consistency, have been investigated in a variety of settings. Binary classification methods can be generalized in many ways to handle multiple classes. It turns out that one can lose consistency in generalizing a binary… (More)

In this paper, we theoretically study the problem of binary classification in the presence of random classification noise — the learner, instead of seeing the true labels , sees labels that have independently been flipped with some small probability. Moreover, random label noise is class-conditional — the flip probability depends on the class. We provide… (More)

We consider the problem of selecting, from among the arms of a stochastic n-armed bandit, a subset of size m of those arms with the highest expected rewards, based on efficiently sampling the arms. This " subset selection " problem finds application in a variety of areas. In the authors' previous work (Kalyanakrishnan & Stone, 2010), this problem is framed… (More)

We describe and analyze two stochastic methods for 1 regularized loss minimization problems, such as the Lasso. The first method updates the weight of a single feature at each iteration while the second method updates the entire weight vector but only uses a single training example at each iteration. In both methods, the choice of fea-ture/example is… (More)

- John C. Duchi, Shai Shalev-Shwartz, Yoram Singer, Ambuj Tewari
- COLT
- 2010

We present a new method for regularized convex optimization and analyze it under both online and stochastic optimization settings. In addition to unifying previously known first-order algorithms, such as the projected gradient method, mirror descent, and forward-backward splitting, our method yields new analysis and algorithms. We also derive specific… (More)

- Prateek Jain, Ambuj Tewari, Purushottam Kar
- NIPS
- 2014

The Goal Analyze a class of effective and scalable iterative methods for high-dimensional statistical estimation problems.

- Sham M. Kakade, Karthik Sridharan, Ambuj Tewari
- NIPS
- 2008

This work characterizes the generalization ability of algorithms whose predictions are linear in the input vector. To this end, we provide sharp bounds for Rademacher and Gaussian complexities of (constrained) linear classes, which directly lead to a number of generalization bounds. This derivation provides simplified proofs of a number of corollaries… (More)

- Shai Shalev-Shwartz, Ambuj Tewari
- Journal of Machine Learning Research
- 2009

We describe and analyze two stochastic methods for <i>l</i><sub>1</sub> regularized loss minimization problems, such as the Lasso. The first method updates the weight of a single feature at each iteration while the second method updates the entire weight vector but only uses a single training example at each iteration. In both methods, the choice of… (More)

- Pradeep Ravikumar, Ambuj Tewari, Eunho Yang
- AISTATS
- 2011

We study the consistency of listwise ranking methods with respect to the popular Normalized Discounted Cumulative Gain (NDCG) criterion. State of the art listwise approaches replace NDCG with a surrogate loss that is easier to optimize. We characterize NDCG consistency of surrogate losses to discover a surprising fact: several commonly used sur-rogates are… (More)

- Sham M. Kakade, Shai Shalev-Shwartz, Ambuj Tewari
- ICML
- 2008

This paper introduces the Banditron, a variant of the Perceptron [Rosenblatt, 1958], for the multiclass bandit setting. The multiclass bandit setting models a wide range of practical supervised learning applications where the learner only receives partial feedback (referred to as "bandit" feedback, in the spirit of multi-armed bandit models) with respect to… (More)