FA-82922 / Go territory scoring / Member archive

Superko only compares against the position before the last move · case 02

Triple ko and longer cycles are accepted as legal.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Input [history, candidate_board, player_to_move_after, mode]; history is a list of [board, player_to_move]. Positional mode forbids any earlier board equal to the candidate; situational mode additionally requires the same player to move. Return the earliest matching history index or "legal".

Why this case matters

Go servers and scoring tools compute this value automatically; a wrong answer changes a game result.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
superko case 0	`"legal"`	`5`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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