References

The following resources directly inspired BitBully's implementation. They are excellent reading for anyone interested in solved games or strong search heuristics. Citations resolve into the auto-generated Bibliography page.

Foundational papers

• L. V. Allis, A Knowledge-based Approach of Connect-Four — The Game is Solved: White Wins, Master's thesis, Vrije Universiteit Amsterdam, 1988. [allis88]
• A. Plaat, J. Schaeffer, W. Pijls, A. de Bruin, Best-First Fixed-Depth Minimax Algorithms, Artificial Intelligence 87 (1996), 255–293 — the original MTD(f) paper. [plaat96]
• J. Schaeffer, The History Heuristic and Alpha-Beta Search Enhancements in Practice, IEEE PAMI, 11 (1989). [schaeffer89]

Code that influenced BitBully

• Pascal Pons, Solving Connect Four — Tutorial Series, http://blog.gamesolver.org/. [pons17]
• John Tromp, John's Connect Four Playground, https://tromp.github.io/c4/c4.html. [tromp08]
• Sean E. Anderson, Bit Twiddling Hacks, https://graphics.stanford.edu/~seander/bithacks.html.

Useful sequences

• A212693 — number of distinct Connect-4 positions reachable after n plies. https://oeis.org/A212693