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Willie Neiswanger

36 accepted papers

2026

Auditing Black-Box LLM APIs with a Rank-Based Uniformity Test

ICLR 2026poster

As API access becomes a primary interface to large language models (LLMs), users often interact with black-box systems that offer little transparency into the deployed model. To reduce costs or maliciously alter model behaviors, API providers may discreetly serve quantized or fine-tuned variants, wh…

Cited by 0SourcecodeScholar
2026

Demystifying and Enhancing the Efficiency of Large Language Model Based Search Agents

ICLR 2026poster

Large Language Model (LLM)-based search agents have shown remarkable capabilities in solving complex tasks by dynamically decomposing problems and addressing them through interleaved reasoning and retrieval. However, this interleaved paradigm introduces substantial efficiency bottlenecks. First, we…

Cited by 0SourcecodeScholar
2026

Hubble: a Model Suite to Advance the Study of LLM Memorization

ICLR 2026oral

We present Hubble, a suite of open-source large language models (LLMs) for the scientific study of LLM memorization. Hubble models come as minimal pairs: standard models are pretrained on a large English corpus, and perturbed models are trained in the same way but with controlled insertion of text (…

Cited by 0SourcecodeScholar
2026

Tina: Tiny Reasoning Models via LoRA

ICLR 2026poster

How cost-effectively can strong reasoning abilities be achieved in language models? Driven by this question, we present Tina, a family of tiny reasoning models achieved with high cost-efficiency. Tina shows that substantial reasoning performance can be developed using only minimal resources, by appl…

Cited by 0SourcecodeScholar
2026

Zebra-CoT: A Dataset for Interleaved Vision-Language Reasoning

ICLR 2026poster

Humans often rely on visual aids, such as diagrams or sketches, when tackling complex problems. Teaching multimodal models to adopt similar strategies, a process known as Visual Chain of Thought (visual CoT), is much more difficult. The main challenges are: (1) weak performance of off-the-shelf visu…

Cited by 0SourcecodeScholar
2025

DeLLMa: Decision Making Under Uncertainty with Large Language Models

ICLR 2025spotlight

The potential of large language models (LLMs) as decision support tools is increasingly being explored in fields such as business, engineering, and medicine, which often face challenging tasks of *decision-making under uncertainty*. In this paper, we show that directly prompting LLMs on these types…

Cited by 5SourcePDFScholar
2025

Efficient Evaluation of Multi-Task Robot Policies With Active Experiment Selection

CoRL 2025poster

Evaluating learned robot control policies to determine their performance costs the experimenter time and effort. As robots become more capable in accomplishing diverse tasks, evaluating across all these tasks becomes more difficult as it is impractical to test every policy on every task multiple tim…

Cited by 0SourceScholar
2025

LiveBench: A Challenging, Contamination-Limited LLM Benchmark

ICLR 2025spotlight

Test set contamination, wherein test data from a benchmark ends up in a newer model's training set, is a well-documented obstacle for fair LLM evaluation and can quickly render benchmarks obsolete. To mitigate this, many recent benchmarks crowdsource new prompts and evaluations from human or LLM jud…

2025

What is Your Data Worth to GPT? LLM-Scale Data Valuation with Influence Functions

NeurIPS 2025poster

Large language models (LLMs) are trained on a vast amount of human-written data, but data providers often remain uncredited. In response to this issue, data valuation (or data attribution), which quantifies the contribution or value of each data to the model output, has been discussed as a potential…

Cited by 0SourcecodeScholar
2024

Uncertainty Quantification for Forward and Inverse Problems of PDEs via Latent Global Evolution

AAAI 2024technical

Deep learning-based surrogate models have demonstrated remarkable advantages over classical solvers in terms of speed, often achieving speedups of 10 to 1000 times over traditional partial differential equation (PDE) solvers. However, a significant challenge hindering their widespread adoption in bo…

2023

Betty: An Automatic Differentiation Library for Multilevel Optimization

ICLR 2023top-5%

Gradient-based multilevel optimization (MLO) has gained attention as a framework for studying numerous problems, ranging from hyperparameter optimization and meta-learning to neural architecture search and reinforcement learning. However, gradients in MLO, which are obtained by composing best-respon…

2023

Generative Modeling Helps Weak Supervision (and Vice Versa)

ICLR 2023poster

Many promising applications of supervised machine learning face hurdles in the acquisition of labeled data in sufficient quantity and quality, creating an expensive bottleneck. To overcome such limitations, techniques that do not depend on ground truth labels have been studied, including weak superv…

2023

Importance-aware Co-teaching for Offline Model-based Optimization

NeurIPS 2023poster

Offline model-based optimization aims to find a design that maximizes a property of interest using only an offline dataset, with applications in robot, protein, and molecule design, among others. A prevalent approach is gradient ascent, where a proxy model is trained on the offline dataset and then…

2023

Making Scalable Meta Learning Practical

NeurIPS 2023poster

Despite its flexibility to learn diverse inductive biases in machine learning programs, meta learning (i.e.,\ learning to learn) has long been recognized to suffer from poor scalability due to its tremendous compute/memory costs, training instability, and a lack of efficient distributed training sup…

2023

Near-optimal Policy Identification in Active Reinforcement Learning

ICLR 2023top-5%

Many real-world reinforcement learning tasks require control of complex dynamical systems that involve both costly data acquisition processes and large state spaces. In cases where the expensive transition dynamics can be readily evaluated at specified states (e.g., via a simulator), agents can oper…

Cited by 8SourcePDFScholar
2023

Offline Imitation Learning with Suboptimal Demonstrations via Relaxed Distribution Matching

AAAI 2023technical

Offline imitation learning (IL) promises the ability to learn performant policies from pre-collected demonstrations without interactions with the environment. However, imitating behaviors fully offline typically requires numerous expert data. To tackle this issue, we study the setting where we have…

Cited by 18SourcePDFScholar
2022

A General Recipe for Likelihood-free Bayesian Optimization

ICML 2022oral

The acquisition function, a critical component in Bayesian optimization (BO), can often be written as the expectation of a utility function under a surrogate model. However, to ensure that acquisition functions are tractable to optimize, restrictions must be placed on the surrogate model and utility…

2022

An Experimental Design Perspective on Model-Based Reinforcement Learning

ICLR 2022poster

In many practical applications of RL, it is expensive to observe state transitions from the environment. For example, in the problem of plasma control for nuclear fusion, computing the next state for a given state-action pair requires querying an expensive transition function which can lead to many…

Cited by 36SourcePDFScholar
2022

Exploration via Planning for Information about the Optimal Trajectory

NeurIPS 2022accept

Many potential applications of reinforcement learning (RL) are stymied by the large numbers of samples required to learn an effective policy. This is especially true when applying RL to real-world control tasks, e.g. in the sciences or robotics, where executing a policy in the environment is costly.…

2022

Generalizing Bayesian Optimization with Decision-theoretic Entropies

NeurIPS 2022accept

Bayesian optimization (BO) is a popular method for efficiently inferring optima of an expensive black-box function via a sequence of queries. Existing information-theoretic BO procedures aim to make queries that most reduce the uncertainty about optima, where the uncertainty is captured by Shannon e…

Cited by 14SourcePDFScholar
2022

Uncertainty Quantification with Pre-trained Language Models: A Large-Scale Empirical Analysis

EMNLP 2022finding

Pre-trained language models (PLMs) have gained increasing popularity due to their compelling prediction performance in diverse natural language processing (NLP) tasks. When formulating a PLM-based prediction pipeline for NLP tasks, it is also crucial for the pipeline to minimize the calibration erro…

2021

BANANAS: Bayesian Optimization with Neural Architectures for Neural Architecture Search

AAAI 2021technical

Over the past half-decade, many methods have been considered for neural architecture search (NAS). Bayesian optimization (BO), which has long had success in hyperparameter optimization, has recently emerged as a very promising strategy for NAS when it is coupled with a neural predictor. Recent work…

2021

Bayesian Algorithm Execution: Estimating Computable Properties of Black-box Functions Using Mutual Information

ICML 2021spotlight

In many real world problems, we want to infer some property of an expensive black-box function f, given a budget of T function evaluations. One example is budget constrained global optimization of f, for which Bayesian optimization is a popular method. Other properties of interest include local opti…

2021

Beyond Pinball Loss: Quantile Methods for Calibrated Uncertainty Quantification

NeurIPS 2021poster

Among the many ways of quantifying uncertainty in a regression setting, specifying the full quantile function is attractive, as quantiles are amenable to interpretation and evaluation. A model that predicts the true conditional quantiles for each input, at all quantile levels, presents a correct and…

Cited by 117SourcePDFScholar
2021

Interactive Weak Supervision: Learning Useful Heuristics for Data Labeling

ICLR 2021poster

Obtaining large annotated datasets is critical for training successful machine learning models and it is often a bottleneck in practice. Weak supervision offers a promising alternative for producing labeled datasets without ground truth annotations by generating probabilistic labels using multiple n…

2021

Personalized Benchmarking with the Ludwig Benchmarking Toolkit

NeurIPS 2021poster

The rapid proliferation of machine learning models across domains and deployment settings has given rise to various communities (e.g. industry practitioners) which seek to benchmark models across tasks and objectives of personal value. Unfortunately, these users cannot use standard benchmark results…

Cited by 0SourcecodeScholar
2021

Synthetic Benchmarks for Scientific Research in Explainable Machine Learning

NeurIPS 2021poster

As machine learning models grow more complex and their applications become more high-stakes, tools for explaining model predictions have become increasingly important. This has spurred a flurry of research in model explainability and has given rise to feature attribution methods such as LIME and SHA…

Cited by 86SourcecodeScholar
2020

A Study on Encodings for Neural Architecture Search

NeurIPS 2020spotlight

Neural architecture search (NAS) has been extensively studied in the past few years. A popular approach is to represent each neural architecture in the search space as a directed acyclic graph (DAG), and then search over all DAGs by encoding the adjacency matrix and list of operations as a set of hy…

2020

ChemBO: Bayesian Optimization of Small Organic Molecules with Synthesizable Recommendations

AISTATS 2020poster

In applications such as molecule design or drug discovery, it is desirable to have an algorithm which recommends new candidate molecules based on the results of past tests. These molecules first need to be synthesized and then tested for objective properties. We describe ChemBO, a Bayesian optimizat…

2019

Myopic Posterior Sampling for Adaptive Goal Oriented Design of Experiments

ICML 2019oral

Bayesian methods for adaptive decision-making, such as Bayesian optimisation, active learning, and active search have seen great success in relevant applications. However, real world data collection tasks are more broad and complex, as we may need to achieve a combination of the above goals and/or a…

2018

Neural Architecture Search with Bayesian Optimisation and Optimal Transport

NeurIPS 2018spotlight

Bayesian Optimisation (BO) refers to a class of methods for global optimisation of a function f which is only accessible via point evaluations. It is typically used in settings where f is expensive to evaluate. A common use case for BO in machine learning is model selection, where it is not possible…

2016

Parallel and Distributed Block-Coordinate Frank-Wolfe Algorithms

ICML 2016poster

We study parallel and distributed Frank-Wolfe algorithms; the former on shared memory machines with mini-batching, and the latter in a delayed update framework. In both cases, we perform computations asynchronously whenever possible. We assume block-separable constraints as in Block-Coordinate Frank…

Cited by 56SourcePDFScholar