Strategic Differences: Area Scoring versus Territory Scoring

Definitions

• "Scoring" is the general definition of the mapping of every possible final position to some score.
• "Counting" is the practical, mechanical procedure for determining the score of the final position of a particular game.
• "Area Scoring" scores the numbers of each player's stones on the board plus empty intersections surrounded only by his stones.
• "Territory Scoring" scores the numbers of each player's prisoners of opposing colour plus empty intersections surrounded only by his stones. This applies only when no further removals will occur. This applies only to those empty intersections that are qualified by an additional status criterion.

Examples

• Area Scoring is an example of a scoring method.
• Territory Scoring is an example of a scoring method.
• Ing Fill-in Counting  is an example of a counting procedure for Area Scoring.
• New Zealand Half Counting is an example of a counting procedure for Area Scoring.
• Chinese Half Counting is an example of a counting procedure for Area Scoring.
• Japanese Fill-in Counting is an example of a counting procedure for Territory Scoring.

Not Considered

• Komi.
• Rare or very rare shapes. Very rare shapes are not considered just because their discussion might have been popular in the past - they are not relevant.
• Scarce, rare, or very rare long cycle shapes are not considered here because their behaviour depends more on the ko rules than on the scoring method.
• The scarce practical differences between Life and Death Territory Scoring and Control Territory Scoring.

Strategic Differences: Area Scoring versus Territory Scoring

Neutral Intersections (Dame)

• Area Scoring: Each "neutral intersection" is worth 1 point for the score. Since neutral intersections (which do not threaten an attack) can be filled alternately, the first player to occpuy a neutral intersection (which does not threaten an attack) gains 1 point.
• Territory Scoring: Each "neutral intersection" itself is worth 0 points for the score.

• Area Scoring rulesets: Usually the rules do not create side conditions. (Ing rules are a bit unclear here.)
• Japanese 1989 Rules, Japanese 2003 Rules: Usually the score differs if either "neutral intersections" are filled or "neutral intersections" are not filled. The definition of territory depends on whether a group of stones is adjacent to "neutral intersections". In practice under the Japanese 1989 Rules, "neutral intersections" outside coexistences are filled during the alternation or the "confirmation phase".
• Korean 1992 Rules, World Amateur Go Championship 1979 Rules: It is mandatory to fill "neutral intersections". However, obviously this does not apply to all "neutral intersections" because there can be "neutral intersections" in coexistences.
• New Amateur-Japanese Rules: Although the rules do not create side conditions, application of the rules becomes easier if "neutral intersections" are filled as far as possible.
• Verbal amateur-Japanese rules: "Neutral intersections" outside coexistences are filled during the alternation, the "confirmation phase", or the counting.

• While reasons for filling "neutral intersections" vary considerably, they are filled somehow under all common rulesets.
• Area Scoring rulesets do not need to encourage the players to fill "neutral intersections" because each "neutral intersection" is worth 1 point for the score.
• For a Territory Scoring ruleset, a prescription to fill certain "neutral intersections" is either very ambiguous or extremely technical. Therefore it is very doubtful to prescribe this in the core rules of play. However, a guideline in the tournament rules might be possible: "During the alternation, the players should fill as many so called "neutral intersections" as possible."

Last Endgame Ko

# # . # .
# # # # #
O # . # O
. O O O O
O O . O .

• Area Scoring: If it is Black's turn, then Black captures, White occupies the neutral intersection, and Black connects - the sum points gained in the ko and on the neutral intersection are 1. If it is White's turn, then White connects and Black occupies the neutral intersection - the sum points gained in the ko and on the neutral intersection are -1. (Negative numbers of points favour White.) Between Black's turn and White's turn, the difference in gained points is 1 - (-1) = 2.
• Territory Scoring: If it is Black's turn, then Black captures, White occupies the neutral intersection, and Black connects - the sum points gained in the ko and on the neutral intersection are 1. If it is White's turn, then White connects and Black occupies the neutral intersection - the sum points gained in the ko and on the neutral intersection are 0. Between Black's turn and White's turn, the difference in gained points is 1 - 0 = 1.

Asymmetrical Coexistences (Sekis)

O . # . #
. O # # #
# # O O O
. # O . O
# # O O .

• Area Scoring: Black wins by 1 point.
• Territory Scoring (in typically occurring rulesets): White wins by 2 points.

One-sided Neutral Intersections

O O O O O O O .
# # # # # # O O
# . O O . # O .
# # O O . # O O

• Area Scoring: White gets 1 extra point in the coexistence.
• Territory Scoring: White gets 0 extra points in the coexistence.