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Dean Foster

10 accepted papers

2025

How Does Critical Batch Size Scale in Pre-training?

ICLR 2025poster

Training large-scale models under given resources requires careful design of parallelism strategies. In particular, the efficiency notion of critical batch size (CBS), concerning the compromise between time and compute, marks the threshold beyond which greater data parallelism leads to diminishing r…

2025

Mind the Gap: Examining the Self-Improvement Capabilities of Large Language Models

ICLR 2025oral

Self-improvement is a mechanism in Large Language Model (LLM) pre-training, post-training and test-time inference. We explore a framework where the model verifies its own outputs, filters or reweights data based on this verification, and distills the filtered data. Despite several empirical success…

Cited by 4SourcePDFScholar
2024

A Study on the Calibration of In-context Learning

NAACL 2024long

Accurate uncertainty quantification is crucial for the safe deployment of machine learning models, and prior research has demonstrated improvements in the calibration of modern language models (LMs). We study in-context learning (ICL), a prevalent method for adapting static LMs through tailored prom…

2022

A Few Expert Queries Suffices for Sample-Efficient RL with Resets and Linear Value Approximation

NeurIPS 2022accept

The current paper studies sample-efficient Reinforcement Learning (RL) in settings where only the optimal value function is assumed to be linearly-realizable. It has recently been understood that, even under this seemingly strong assumption and access to a generative model, worst-case sample complex…

Cited by 7SourcePDFScholar
2021

The Benefits of Implicit Regularization from SGD in Least Squares Problems

NeurIPS 2021poster

Stochastic gradient descent (SGD) exhibits strong algorithmic regularization effects in practice, which has been hypothesized to play an important role in the generalization of modern machine learning approaches. In this work, we seek to understand these issues in the simpler setting of linear regre…

Cited by 40SourcePDFScholar
2021

Top-k eXtreme Contextual Bandits with Arm Hierarchy

ICML 2021spotlight

Motivated by modern applications, such as online advertisement and recommender systems, we study the top-$k$ extreme contextual bandits problem, where the total number of arms can be enormous, and the learner is allowed to select $k$ arms and observe all or some of the rewards for the chosen arms. W…

Cited by 31SourcePDFScholar
2021

Variance Reduced Training with Stratified Sampling for Forecasting Models

ICML 2021spotlight

In large-scale time series forecasting, one often encounters the situation where the temporal patterns of time series, while drifting over time, differ from one another in the same dataset. In this paper, we provably show under such heterogeneity, training a forecasting model with commonly used stoc…

Cited by 24SourcePDFScholar
2021

What are the Statistical Limits of Offline RL with Linear Function Approximation?

ICLR 2021spotlight

Offline reinforcement learning seeks to utilize offline (observational) data to guide the learning of (causal) sequential decision making strategies. The hope is that offline reinforcement learning coupled with function approximation methods (to deal with the curse of dimensionality) can provide a m…

Cited by 198SourcePDFScholar
2019

Deep Factors for Forecasting

ICML 2019oral

Producing probabilistic forecasts for large collections of similar and/or dependent time series is a practically highly relevant, yet challenging task. Classical time series models fail to capture complex patterns in the data and multivariate techniques struggle to scale to large problem sizes, but…

Cited by 247SourcePDFScholar
2015

Finding Linear Structure in Large Datasets with Scalable Canonical Correlation Analysis

ICML 2015poster

Canonical Correlation Analysis (CCA) is a widely used spectral technique for finding correlation structures in multi-view datasets. In this paper, we tackle the problem of large scale CCA, where classical algorithms, usually requiring computing the product of two huge matrices and huge matrix decomp…

Cited by 102SourcePDFScholar