I'm a second-year PhD student at Aalto University and the ELLIS Institute Finland, supervised by Prof. Samuel Kaski. My research focuses on meta-learning, amortized inference, and Bayesian optimization.

Before the PhD, I completed my Master's in Computer Science at Aalto University, and Bachelor's in Computer Science and Engineering at Harbin Institute of Technology, Shenzhen. Outside research I enjoy bouldering 🧗 and doodling 🖊️.

ICLR 2026

In-Context Multi-Objective Optimization

Xinyu Zhang, Conor Hassan, Julien Martinelli, Daolang Huang, Samuel Kaski

A dimension-agnostic transformer that replaces the surrogate-plus-acquisition stack of (multi-objective) Bayesian optimization with a single forward pass; 50–1000× faster proposal time at matched Pareto quality.

ICML 2026

Constrained Bayesian Experimental Design via Online Planning

Yujia Guo, Daolang Huang, Xinyu Zhang, Samuel Kaski, Ayush Bharti

Enables constrained Bayesian experimental design by combining offline pre-training of an amortized policy and a posterior network with online multi-step lookahead planning using scenario trees.

ICLR 2025 Spotlight · top 5%

PABBO: Preferential Amortized Black-Box Optimization

Xinyu Zhang, Daolang Huang, Samuel Kaski, Julien Martinelli

A transformer neural process trained with reinforcement learning that fully amortizes preferential Bayesian optimization: meta-learning both the surrogate and the acquisition function. Several orders of magnitude faster than Gaussian-process baselines, and often more accurate.

Workshops & Preprints

IJCAI XAI Workshop 2024

Challenges in Interpretability of Additive Models

Xinyu Zhang, Julien Martinelli, ST John

Generalized additive models — including their recent neural-network variants — exhibit multiple forms of nonidentifiability that complicate interpretation. We argue for restraint when claiming such models as interpretable or suitable for safety-critical applications.