Sanko 求解器首次算出超级劫规则下的围棋盘面价值
Solving Go under Positional Superko: Sound Proof Transfer and New Board Values
有人写了个叫 Sanko 的求解器，把中国规则里的超级劫真算明白了，5x5 从 5 小时压到 16 分钟，还顺手解了 11 个没人解过的棋盘，代码全开源。
arXiv 论文提出 Sanko，一个并行深度优先证明数求解器，专门处理中国规则中的位置超级劫（PSK）。核心是一个证明迁移定理：除非胜方必须重建的盘面已出现过，已有证明在新路径上仍然有效。Sanko 用 6 线程 16 分钟证明 5x5 围棋，此前最优方法需 5.25 小时；在 192 线程机器上约 90 秒完成。它还首次给出 23 个棋盘在 PSK 下的价值，其中 11 个在任何规则下此前未被求解；超级劫会改变博弈价值，如 4x7 在基本劫规则下是全盘胜，在 PSK 下仅值 12 目。
Solving Go under Positional Superko: Sound Proof Transfer and New Board Values
Positional superko (PSK) forbids recreating any earlier whole-board position. It is part of the Chinese rules as written and of the rules used in computer Go. Yet almost all solved Go boards were computed under a simpler basic-ko rule set. PSK makes solving hard: legality depends on the whole game history, and this breaks the three tools that make solving tractable, namely transposition tables (the graph-history interaction problem), static life-and-death recognition, and safe move pruning. We present Sanko, a parallel depth-first proof-number solver that restores all three soundly. Its core is a cheap proof-transfer theorem: a stored proof stays valid on a new path unless a board that the proof's winner must create has already occurred. Sanko proves 5x5 Go in 16 minutes with six threads, where the previous state of the art needed 5.25 hours with six processes, and in about a minute and a half on one 192-thread machine. It also establishes the first PSK values of twenty-three further boards, eleven of which were unsolved under any rules. Superko changes game-theoretic values: 4x7, a full-board win under basic ko, is worth only 12 points under PSK, and we pinpoint the move at which the previously published optimal line fails. Unlike earlier solutions of empty Go boards, we release the solver source together with the command line and outcome of every run behind our values and measurements, so that all reported values can be reproduced.