Papers & Talks

Papers

Paper produced by The bbchallenge Collaboration:

• Determination of the fifth Busy Beaver value. The bbchallenge Collaboration, J. Blanchard, Daniel Briggs, Konrad Deka, Nathan Fenner, Yannick Forster, Georgi Georgiev (Skelet), Matthew L. House, Rachel Hunter, Iijil, Maja Kądziołka, Pavel Kropitz, Shawn Ligocki, mxdys, Mateusz Naściszewski, savask, Tristan Stérin, Chris Xu, Jason Yuen, Théo Zimmermann. https://arxiv.org/abs/2509.12337 (github)
• Turing machines deciders, part I. The bbchallenge Collaboration, J. Blanchard, K. Deka, N. Fenner, T. Guilfoyle, Iijil, M. Kądziołka, P. Kropitz, S. Ligocki, P. Michel, M. Naściszewski, and T. Stérin. Apr. 2025. https://arxiv.org/abs/2504.20563

Paper produced by community members:

• Stérin, T., Woods, D. (2024). Hardness of Busy Beaver Value BB(15). In: Kovács, L., Sokolova, A. (eds) Reachability Problems. RP 2024. Lecture Notes in Computer Science, vol 15050. Springer, Cham. https://doi.org/10.1007/978-3-031-72621-7_9
  • Paper: arxiv version (first released in 2021), conference version
  • Talk on September 25th 2024 at RP 2024 in Vienna: talk recording, talk recording (compressed), talk slides
• Xu, C. (2024). Skelet #17 and the fifth Busy Beaver number. Arxiv preprint

Talks

• Le cinquième nombre Busy Beaver. Talk by Tristan Stérin at the seminar of Prof. Timothy Gowers College de France's lectures , October 27th 2025.
• Determination of the fifth Busy Beaver value. Poster by The bbchallenge Collaboration and Tristan Stérin presented at the 31st International Conference on DNA Computing and Molecular Programming DNA31. (poster PDF) (poster SVG)
• Coq proof of the fifth Busy Beaver value. Talk given by Tristan Stérin at Types 2025, Glasgow, Scotland, June 9th 2025. (slides) (links)
• Formal verification of the 5th Busy Beaver value. Talk given by Maja Kądziołka and Tristan Stérin at Cambridge's seminar "Formalisation of mathematics with interactive theorem provers", March 13th 2025. (recording) (slides, part 1) (interactive slides, part 2)