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Sasha Petrov

Long-tenured contributor

Based in Bay Area
Node-cell voronoi-19
ORCID 0000-8121-3393-3039

Research

Sasha co-led the counterfactual rollouts deployment study that is the closest thing the world-models axis has to a production case study. The study put confidence-weighted what-if simulations into two cells' production planners for a month, and reported on what changed; the result is now used as an example of how the axis treats internal benchmarks.

He is the world-models axis steward, in his second term, with the term ending 2026-Q1. He runs the axis's quarterly cross-cell review pool with what colleagues describe as 'unromantic seriousness' — meaning, he expects pre-registered claims to actually match what the runs produced.

Sasha co-organises an annual workshop on operator-based dynamics at NeurIPS. He has a habit of asking questions at talks that begin with 'I think your result is interesting and I want to argue with it,' and the lab finds this useful.

Background

Ph.D. computer science, MIT, 2014. Undergraduate at Moscow State University (applied mathematics).

Prior to alphabell: MIT CSAIL; Halcyon Safety; Cardinal Lab.

Selected publications

Full publications index →

Recent talks

  • Counterfactual rollouts — 30 days in production, RL Theory Workshop 2025
  • The shape of a world model's failure, NeurIPS 2024
  • Why the second author matters, MIT EECS seminar 2024
Working with

Sasha is currently part of node-cell voronoi-19, working under the World models research axis. The cell is open to substantive correspondence from researchers working on adjacent problems; route requests through voronoi-19@alphabell.com or directly to Sasha at sasha-petrov@alphabell.com.