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When Are Two Scores Better Than One? Investigating Ensembles of Diffusion Models

Razafindralambo, Raphaël, Sun, Rémy, Precioso, Frédéric, Garreau, Damien, Mattei, Pierre-Alexandre

arXiv.org Machine Learning

Diffusion models now generate high-quality, diverse samples, with an increasing focus on more powerful models. Although ensembling is a well-known way to improve supervised models, its application to unconditional score-based diffusion models remains largely unexplored. In this work we investigate whether it provides tangible benefits for generative modelling. We find that while ensembling the scores generally improves the score-matching loss and model likelihood, it fails to consistently enhance perceptual quality metrics such as FID on image datasets. We confirm this observation across a breadth of aggregation rules using Deep Ensembles, Monte Carlo Dropout, on CIF AR-10 and FFHQ. We attempt to explain this discrepancy by investigating possible explanations, such as the link between score estimation and image quality. We also look into tabular data through random forests, and find that one aggregation strategy outperforms the others. Finally, we provide theoretical insights into the summing of score models, which shed light not only on ensembling but also on several model composition techniques (e.g.


A self-driving lab for solution-processed electrochromic thin films

Dahms, Selma, Torresi, Luca, Bandesha, Shahbaz Tareq, Hansmann, Jan, Röhm, Holger, Colsmann, Alexander, Schott, Marco, Friederich, Pascal

arXiv.org Artificial Intelligence

Solution-processed electrochromic materials offer high potential for energy-efficient smart windows and displays. Their performance varies with material choice and processing conditions. Electrochromic thin film electrodes require a smooth, defect-free coating for optimal contrast between bleached and colored states. The complexity of optimizing the spin-coated electrochromic thin layer poses challenges for rapid development. This study demonstrates the use of self-driving laboratories to accelerate the development of electrochromic coatings by coupling automation with machine learning. Our system combines automated data acquisition, image processing, spectral analysis, and Bayesian optimization to explore processing parameters efficiently. This approach not only increases throughput but also enables a pointed search for optimal processing parameters. The approach can be applied to various solution-processed materials, highlighting the potential of self-driving labs in enhancing materials discovery and process optimization.


Teaching Old Tokenizers New Words: Efficient Tokenizer Adaptation for Pre-trained Models

Purason, Taido, Chizhov, Pavel, Yamshchikov, Ivan P., Fishel, Mark

arXiv.org Artificial Intelligence

Tokenizer adaptation plays an important role in transferring pre-trained language models to new domains or languages. In this work, we address two complementary aspects of this process: vocabulary extension and pruning. The common approach to extension trains a new tokenizer on domain-specific text and appends the tokens that do not overlap with the existing vocabulary, which often results in many tokens that are unreachable or never used. We propose continued BPE training, which adapts a pre-trained tokenizer by continuing the BPE merge learning process on new data. Experiments across multiple languages and model families show that this approach improves tokenization efficiency and leads to better utilization of added vocabulary. We also introduce leaf-based vocabulary pruning, which removes redundant tokens while preserving model quality. Together, these methods provide practical tools for controlled vocabulary modification, which we release as an open-source package.


Sick baby ants sacrifice themselves to save their colony

Popular Science

New research shows ill pupae emit a chemical signal before ever leaving their cocoons. Breakthroughs, discoveries, and DIY tips sent every weekday. Ants are some of nature's most selfless animals. They practice social distancing when ill, consistently act for the good of the colony, and will die to protect their queen from outsiders. This evolutionary drive is so strong that at least one ant species will even willingly sacrifice before they leave their cocoons.