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Felix Draxler

14 accepted papers

2026

Beyond Accuracy: Are Time Series Foundation Models Well-Calibrated?

ICLR 2026poster

The recent development of foundation models for time series data has generated considerable interest in using such models across a variety of applications. Although foundation models achieve state-of-the-art predictive performance, their calibration properties remain relatively underexplored, despi…

Cited by 0SourcecodeScholar
2026

Calibrated Test-Time Guidance for Bayesian Inference

ICML 2026poster

Test-time guidance is a widely used mechanism for steering pre-trained diffusion models toward outcomes specified by a reward function. Existing approaches, however, focus on reward maximization rather than sampling from the true Bayesian posterior, leading to miscalibrated inference. In this work, …

Cited by 0SourceScholar
2026

Parallel Token Generation for Language Models

ICLR 2026poster

Autoregressive transformers are the backbone of modern large language models. Despite their success, inference remains slow due to strictly sequential prediction. Prior attempts to predict multiple tokens per step typically impose independence assumptions across tokens, which limits their ability to…

Cited by 0SourceScholar
2025

TRADE: Transfer of Distributions between External Conditions with Normalizing Flows

AISTATS 2025poster

Modeling distributions that depend on external control parameters is a common scenario in diverse applications like molecular simulations, where system properties like temperature affect molecular configurations. Despite the relevance of these applications, existing solutions are unsatisfactory as t…

Cited by 0SourcecodeScholar
2025

Transformers for Mixed-type Event Sequences

NeurIPS 2025spotlight

Event sequences appear widely in domains such as medicine, finance, and remote sensing, yet modeling them is challenging due to their heterogeneity: sequences often contain multiple event types with diverse structures—for example, electronic health records that mix discrete events like medical proce…

Cited by 0SourcecodeScholar
2025

Variational Control for Guidance in Diffusion Models

ICML 2025poster

Diffusion models exhibit excellent sample quality, but existing guidance methods often require additional model training or are limited to specific tasks. We revisit guidance in diffusion models from the perspective of variational inference and control, introducing \emph{Diffusion Trajectory Matchin…

2024

Free-form Flows: Make Any Architecture a Normalizing Flow

AISTATS 2024poster

Normalizing Flows are generative models that directly maximize the likelihood. Previously, the design of normalizing flows was largely constrained by the need for analytical invertibility. We overcome this constraint by a training procedure that uses an efficient estimator for the gradient of the ch…

2024

Learning Distributions on Manifolds with Free-Form Flows

NeurIPS 2024poster

We propose Manifold Free-Form Flows (M-FFF), a simple new generative model for data on manifolds. The existing approaches to learning a distribution on arbitrary manifolds are expensive at inference time, since sampling requires solving a differential equation. Our method overcomes this limitation b…

2024

Lifting Architectural Constraints of Injective Flows

ICLR 2024poster

Normalizing Flows explicitly maximize a full-dimensional likelihood on the training data. However, real data is typically only supported on a lower-dimensional manifold leading the model to expend significant compute on modeling noise. Injective Flows fix this by jointly learning a manifold and the…

Cited by 11SourcePDFScholar
2024

On the Universality of Volume-Preserving and Coupling-Based Normalizing Flows

ICML 2024poster

We present a novel theoretical framework for understanding the expressive power of normalizing flows. Despite their prevalence in scientific applications, a comprehensive understanding of flows remains elusive due to their restricted architectures. Existing theorems fall short as they require the us…

Cited by 5SourcePDFScholar
2023

On the Convergence Rate of Gaussianization with Random Rotations

ICML 2023poster

Gaussianization is a simple generative model that can be trained without backpropagation. It has shown compelling performance on low dimensional data. As the dimension increases, however, it has been observed that the convergence speed slows down. We show analytically that the number of required lay…

2022

Whitening Convergence Rate of Coupling-based Normalizing Flows

NeurIPS 2022accept

Coupling-based normalizing flows (e.g. RealNVP) are a popular family of normalizing flow architectures that work surprisingly well in practice. This calls for theoretical understanding. Existing work shows that such flows weakly converge to arbitrary data distributions. However, they make no stateme…

Cited by 10SourcePDFScholar
2019

On the Spectral Bias of Neural Networks

ICML 2019oral

Neural networks are known to be a class of highly expressive functions able to fit even random input-output mappings with 100% accuracy. In this work we present properties of neural networks that complement this aspect of expressivity. By using tools from Fourier analysis, we highlight a learning bi…

2018

Essentially No Barriers in Neural Network Energy Landscape

ICML 2018oral

Training neural networks involves finding minima of a high-dimensional non-convex loss function. Relaxing from linear interpolations, we construct continuous paths between minima of recent neural network architectures on CIFAR10 and CIFAR100. Surprisingly, the paths are essentially flat in both the…