This is the website for Timo Ewalds' Masters thesis.

Playing and Solving Havannah - The thesis in pdf form.

Castro is the Havannah player, and is open source
ParamLog is a distributed testing framework, also open source

Proof trees are posted below. They include all states in the proof tree that took more than some number of simulations to solve. The higher the threshold, the fewer nodes, and the samller the size. They are in hgf/sgf format, and can be opened by HavannahGui (assuming you have enough memory).
size4-10000000000.hgf.bz2 (1.1kb) - size4-10000000000.hgf (5.7kb)
size4-1000000000.hgf.bz2 (3.5kb) - size4-1000000000.hgf (24.2kb)
size4-100000000.hgf.bz2 (27.8kb) - size4-100000000.hgf (251kb)
size4-10000000.hgf.bz2 (245kb -> 2.5mb)
size4-1000000.hgf.bz2 (2.1mb -> 25mb)
size4-100000.hgf.bz2 (17.3mb -> 223mb)