![]() StartingPoints
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Size and safety of territory
Difficulty: Beginner
Keywords: Life & Death, Tactics, Question
Iago: For beginners such as myself, one of the big questions is to know if a territory is secure or not. As far as I understand, the bigger the better for living, but there should be some kind of limits... Thinking about examples?Suppose White has managed to enclose a territory. Black is considering a possile on it attack; and White is considering defense. Here is a first attempt at classification by size, and my main concerns about it Small enclosureIf the territory is small, this belongs obviously to the realm of life and death.
Ex1: Black is playing to kill, and White to live.
Here both sides have to worry, it's only worth 2 points for White, but letting it die would give 7 points to Black. Andrew Grant: 12 points, not 7. Each dead white stone is worth 2 points. Thus the value of the move at a is 12+2 = 14 points in gote. Iago: Um, not sure I got that ... the value of a dead stone is 2 points because it counts as a prisoner and as a free space ? 14 points in gote means that the one playing here gains 14 points, but lose sente? Andrew Grant: That's correct. You count not just the prisoner but also the point of territory underneath when the prisoner is removed. So each dead stone counts for 2 points. If black plays at a and kills white, there are five dead stones sitting inside a seven point territory, which equals 12 points. Add the two points white would have if she played first to get the full value, 14 points. And yes, 14 points in gote means just what you say - you gain 14 points compared with letting your opponent play there, but you lose sente. Karl Knechtel: The deiri value is 14 points, yes. The miai value is 7 points, since two plays separate the two results. Iago: Uhm... not sure I got that either: I mean if White plays first he lives with 1 move, but killing requires 3 moves if Black plays first... wouldn't that be a swing of 4? And I don't understand how you make those counts with multiple choices... Karl Knechtel: Capturing takes 3 moves; Black doesn't have to capture in order to claim the stones as dead. As for "multiple choices", only the play at a needs to be considered here; other options are dominated?. Perhaps Bill or Charles can explain this better, being so practiced at it? :) Charles Let me try to clarify one thing at a time. The diagram shows seven black stones and five white stones. This can be our baseline for looking at the local tally: it stands currently at BB. If Black adds one to kill, at a, this goes to BBB. If White adds one to live, it goes to B. So that's a difference of two plays, as one expects for a normal gote move. How to deal with several choices? I'd say that conceptually one has to start with a clear vision of tree-representation of the game (or local part of the game). Naturally this is much deeper than a tally concept. Medium enclosureIf White territory is big enough then it cannot be killed, and if it is not too big, then any black stones would be easily captured: a medium territory cannot be killed nor reduced.
Ex2 : a 3x3 territory (ie 9 points). Black cannot kill because White can divide the space easily. Black cannot reduce because there is not enough space for a living shape.
This is discussed in detail at square nine in the corner. TJ: Black can make seki by playing at a. White may want to play there first if there's nothing bigger. Iago: Oops, Seki... well my example is not so good then :/ maybe we should go for a 3x4 then ?
Ex2 bis : a 3x4 territory (ie 12 points). This one should be better : Black cannot reduce nor kill.(correct ?)
I think the limit between small and medium is around 6 or 7, depending on the situation (see Basic live shapes). My first question: what is the limit between medium and big ? Or to be more precise, how much space does black need to make an alive group from scratch (and what shape ? Square like 5x5 or more like 3x8...) ? Big enclosureIf White territory is too big (see upper), then it still cannot be killed, but it may be reduced by Black making live inside or Seki. I guess this is close to Shinogi, because this is where all my questions comes from ! TJ: An odd situation, for sure. I don't think it would happen like this...black can certainly live inside, I'm pretty sure even if White played first. But, shinogi should happen much earlier than this. A moyo is generally not totally walled off when ripe for invasion. Maybe someone else can show a theoretical invasion/defence here, but I think it's too unnatural to worry about. One side, almost surely, would have taken hoshi/made an enclosure around the corner first, and would have been pushing back at that rather odd wall, though. Anyway, not really answering your question, but I hope it helps some. (14 kyu) Iago: Well yeah it is not natural (but maybe in handicap game ?)... my idea was to get a simplified situation in order to watch the Shinogi-kind fight (could be a 4x9 framework with holes in it), instead of a complicated large central moyo fight. the second idea would be to know if Black should invade a large framework or not bother with it, depending on the size, but it may not be the best way to take the problem...
Ex3 : is this too good to be true ? White here has 49 points, and cannot be killed. Can Black reduce it ? and how ? What should White do to avoid that ? Andrew Grant: Assuming good play on White's part, Black cannot invade this corner and live. White's walls are much stronger than they appear.
Ex4 : Black made 2 points, but took more than 16 from white, and still counting. So this is my second question : how should both play in the Ex3 situation ? ConclusionThe main idea is that White wants to know if his territory is safe, to protect it from reduction if needed, but still not making unnecessary plays.
Iago: Well now the page is a good example of beginner's misthinking and mistakes :) Thanks everybody, now it's much clearer for me. And this name is better too; maybe we should link it in some way to territory ? Charles It's linked from territory already: you can read this on the left-hand bar. This is a copy of the living page "Size and safety of territory" at Sensei's Library. ![]() |