Territory Scoring versus Area Scoring

    Keywords: Rules

Although territory scoring and area scoring are largely similar, there are still subtle differences between the two that can affect the outcome of the game.

Example 1

An example where territory scoring and area scoring differs is when there is one last half-point ko to be connected as well as an odd number of neutral points.

In this diagram, with no stones captured and Black to play, under territory scoring, Black has little choice but to connect at a, and lose by one point. Under area scoring connecting at a will also make him lose by one point, but now he has a better way to play.

Under area scoring Black should play the last neutral point at b. White can then capture at a, but Black has a ko-threat at c. After White responds to c, and Black retakes the ko, White does not have a ko-threat, so she will have to pass (or make some inconsequential move), and Black can connect at a. This way, Black wins by one point.



Example 2

Reference: [ext] Go4Go.net article.

The following game is taken from the first round of the 9th Xinren Wang tournament in China, the players are Gu Li 5p (taking White) and Liu Xing 6p. This tournament uses area scoring.

[Diagram]

Liu Xing (White) versus Gu Li.

Black had just taken the half-point ko at BC. This is a game where the margin is at half a point, so whoever wins this ko wins the game.

White has a ko-threat at a, but Black also has a ko-threat at b. A White atari at c will only induce a ko-threat for Black at d. Unable to find any other ko-threats, White resigned at this point.

However, things are not so simple.

[Diagram]

How White can win. (6, 9 takes ko, 11 connects ko)

It was later pointed out that because area scoring is used, White can win by playing this way. Although the atari at W7 seems to lose a point, it is a good move which can turn the tables.

By winning the ko, White occupied two points at W3 and BC while Black occupied one point at B10, compared to Black occupying two points at BC and W3 and White occupying one point at B10 had Black won the ko. The net difference is one point, and so White wins by half a point under area scoring rules had he played this way.

Under territory scoring rules, this sequence would have made no difference to the scoring at all, because White gains the BC stone at the expense of sacrificing the W7 stone, so the net gain is zero compared to simply allowing Black to connect the ko.

iopq: Anyone want to score this game under sunjang baduk scoring? That might be interesting :P


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