Roee Hendel

ML Research Engineer

Roee Hendel

I work at the intersection of ML research and engineering, drawn to the core problems on the way to general intelligence that is useful, efficient and safe.

I have worked in ML for seven years, in industry and in academia. Most recently, at AI21 Labs, I worked across both the infrastructure and the research side of LLM training: the efficiency of large-scale distributed training with reinforcement learning, and the full post-training experimentation process. I was also a core developer of the retrieval systems behind the company’s RAG offering. During my M.Sc. at Tel Aviv University I worked on the mechanistic interpretability of large language models. Earlier, in the IDF, I worked in computer vision, building deep-learning object detection systems.

I’m a graduate of the Talpiot program, with a B.Sc. in Physics and Computer Science from the Hebrew University.

Structured RAG for Answering Aggregative Questions

Omri Koshorek, Niv Granot, Aviv Alloni, Shahar Admati, Roee Hendel, Ido Weiss, Alan Arazi, Shay-Nitzan Cohen, Yonatan Belinkov

arXiv preprint, 2025

Standard retrieval breaks down on questions that have to aggregate over a whole corpus rather than a few passages. We pinpoint that failure and propose a first direction toward solving it.