FA-82918 / Go territory scoring / Member archive

Multi-stone captures create a ko ban · case 03

Capturing two stones marks the first captured point as a ko point.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input [board_after_move, row, col, captured_points]. A ko ban point exists only when exactly one stone was captured, the played stone has no friendly orthogonal neighbour, and it has exactly one liberty. Return the captured point or None.

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
ko point case 6	`[3, 2]`	`null`	Failed

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

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