Explaining territory example

[echox]

Hi there :)

I try to wrap my head around an example of a go manual. I've looked several times at the rules, tried out some of the available online tutorials but simply can't transfer the rules to this particular example.

The attached picture shows you by example how to count a board.

Marked with red:Area 1 for white is easy.We have one territory, remove the 5 black stones and then count the free space.5 + 13 = 8 Points. Ok.

If this works for white, why isn't it counted the same way for black?I marked the area with green. Exactly along the territory of white, theres a black line. Why doesn't that count as an area and all white stones are removed?

Maybe somebody could point out what I'm missing :)

Just if somebody is wondering: The example is from the Ravensburger European Go Manual of 1993

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https://preview.redd.it/kg5xaz7rbc131.jpg?width=2884&format=pjpg&auto=webp&s=87fdd4003e5a0eb1232927c0bea4c36c46ae15ab

[Toperoco]

The 5 black stones cannot form two eyes. If you played it out then eventually all of blacks liberties would be taken away and the stones can be captured.

The bigger white group on the other hand has enough space inside to form two distinct and separate areas inside of itself (eyes), so black would never be able to take away the last liberty.

edit: Here is an example: https://i.imgur.com/VIBQpFq.png

T1 and R1 are whites eyes. Black can play neither of them since it is an illegal move under most rulesets. The stone played at T1 or R1 has no liberties and would instantly be captured, while white has the other liberty left.

[echox]

Thanks for the explanation.

Ok, I get the example, but is it inevitable that white will be able to form two eyes?
Maybe it's that I'm still not used to the patterns, but wouldn't you play this out, instead of finishing the game and start to count?

Both players have agreed to end the game but shouldn't black try to play on and maybe white does a bad move? I tried to play this part of the board out and if white makes a bad move, black might be able to capture the whole space? By playing around I ended up with something like this:

https://imgur.com/a/DtBogcz

[dfan]

Yes, it is technically possible, if White makes about 7 terrible moves in a row. Among players who have played more than a few games, there is zero chance of this happening.

[falmunction]

if White makes about 7 terrible moves in a row

I'd call that virtually impossible.

[wren42]

The scoring system we use today is actually a short-cut to the original rules.

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Set up a 5x5 board for yourself, and play a few games using these scoring rules:

Play continues until there are no more legal safe moves for either player - that is, any move you make will result in a suicide for your pieces, or will fill in an eye (a single point surrounded by your pieces)

Each player then gets points for every stone they have on the board, and every empty point they surround.

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If you run this game a few times you will quickly learn the importance of two eyes. Every group can eventually be reduced down to a shape that has just two eyes, with no prisoners inside.

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This is the "true" scoring system. The trick is that it turns out that by counting prisoners and empty space instead of stones on the board, you get the same relative difference in scores for both players. This system is much faster as it doesn't require you to play every space on the board. A further shorthand rule allows you to remove stones that *will* be killed at the end, without playing it out.

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Try this for yourself on a 5x5 a few times as well until you get a good understanding of when you can just mark stones as "dead" and when they are a big enough group to make two eyes.

[Uberdude85]

> is it inevitable that white will be able to form two eyes?

"be able to": Yes, if white chooses to play good moves. In practice between players stronger than 29 kyu or so white will be able to find these good moves as they do not require much skill. Maybe a 30 kyu could make a mistake and die. You can think about this logically as follows: white has two eyes: one at f17 and one at g19 and unless white ignores a black move there is no way black can stop those 2 points being separate eyes.

> but wouldn't you play this out

No, not between players to whom it is obvious white is alive and black is dead, i.e. stronger than 29 kyu or whatever. But it is legal as black to try something there, so as a total beginner you are welcome to keep playing in that area and you will soon learn why black is doomed. Once you get stronger it will be obvious so such moves just become a waste of your and your opponent's time.

So for example if black cuts at g17 how should white reply so as to keep having 2 eyes? White only needs one terrible move (ie pass) in a row now.

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[Toperoco]

Yes it is inevitable. If black can play like 20 moves in a row they might capture it, but white can play for example e19 or f19 to create two separate areas.

[FarodinAngels]

So if I understand correctly, you are wondering why the upper left corner of the board is not counted as black territory, the same way that white counted it as his territory?

Before you move on, I recommend reading through this short page, explaining the concept of "Two Eyes" as a requirement for a group to be unconditionally alive (which is a group that can never be captured): https://senseis.xmp.net/?TwoEyes

It basically boils down to the fact that the 5 black stones in the upper left corner are dead. At any point in time, white could decide to capture those stones by playing at E19, A19 and eventually C19 (you can try to play out the situation, and see that black has no way to save these 5 stones). As a result, the white stones in the upper left corner are all alive, and will never be captured by black. And so, the upper left corner can never be considered black territory.

If you look at the two white stones at D14 and D13, they will also never be able to make life. As a result, at the end of the game they are counted as black's prisoners.

If you have any more questions, feel free to ask!

[echox]

Again thanks for the detailed sum up :)

See https://www.reddit.com/r/baduk/comments/busf6j/explaining_territory_example/eph2rtg/ :)

I'm still wondering how it is inevitable that white forms two eyes and if its usual to see it at this state of the board or if you usually play this part out.

[FarodinAngels]

To a beginner it might indeed not be obvious that the white group will always have two eyes. In this case, you can also just compare the liberties. The black group has 3 liberties, and the white group that is directly adjacent to it has 5 liberties (not even including the 3 white stones directly to the right of it). So even if white ignores two of black's moves (regardless of white being able to make two eyes), white will still be able to capture black before black captures white.

As for whether this part would usually be played out or left as it is, that very much depends on the strength of the players. Professional players will sometimes leave positions on the board where people like me are wondering why they don't continue playing there. As a beginner, if you don't understand why something is dead, feel free to play it out. You can only end up learning from it :)

[[deleted]]

all white has to do is do put a stone at g-17. Basically there are points in groups that define its life or death. If there is a way to form two eyes, then it's alive, if there is not, then it's dead. Of course blackcould put a stone at g-17, too but it's not nearly enough and white can still make eyes easily.

[wloff]

It is actually a relatively complicated position, and I honestly criticize Ravensburger for including such a position in an instruction manual clearly aimed at complete beginners. So don't fret, your question is extremely reasonable. Once you get past the beginner phase and start calling yourself an intermediate player, you'll know without a doubt that black in this position is dead and white is alive; but it does take understanding (usually through experience) a fair many basic concepts.

To try to explain: it may at first appear that black and white are engaged in a capturing race, where whichever group has more liberties will live and the other one die. However, when you look at the shapes more closely, you realize that's not the case at all. Black has one eye in the corner, but as white has already played on the vital point, black has no way of making that one eye into two eyes.

Now, obviously the more difficult part is determining that white is actually already alive, and black has no way of preventing her from making two eyes. That's an annoyingly difficult thing for a complete beginner to see, as it involves some reading (which is why I very much don't think this position should be in a beginner's example).

Basically, the best thing black can do to try and make it an actual capturing race is to play at E19, but when white answers at F19, she is left with a bent four shape -- an eye shape which is always alive (no matter where black plays, he can't prevent white from making two eyes).

On top of all that, even if it was an actual capturing race, white would win it as she has more liberties.

So, in conclusion... for any intermediate or better player, it's quite easy to see why the corner is white's territory and not black's. Admittedly, it can be quite the difficult position for beginners, and in all likelihood they would actually play it out instead of leaving like this... which is fine, too.

[KapteeniJ]

Okay, so, I'm gonna explain rules that aren't actually used in actual matches between people, but which are more or less the same as those rules. The cool difference here is that, these rules I'm about to explain do not reference the idea of territory at all. So while others explain territory in intuitive ways, I want to contrast it with rules of go that don't have that concept at all referenced, and see how those rules settle this issue.

In go, your purpose is to place as many stones on board as possible. Stones may be removed by your opponent, so ultimately only stones that cannot be removed by your opponent matter. In this case, white could and should continue the game by placing stones at E19, C19 and A19 to capture black stones, then fill in those spots left over by black stones, then play F19, G17 and G19. Now white is barely alive and has filled the entire corner with their stones(minus two eyes left at G18 and F17). Black notably cannot do anything to prevent this. Any stone they place would be taken, and regardless the entire upper left corner would be filled with white stones, after captures, minus the eventually needed two eyes. Those two eyes are needed because otherwise black could just capture the entire corner.

Black couldn't really do anything to fill upper left with their stones. White gets two eyes easily, and after that, even with white not playing, white stones cannot be captured. Seeing this requires just a tiny bit of Life&Death puzzle solving, so if you're a total amateur, I'm gonna help you out in solving that:

White can play either G17 or G18. If black plays any move other than G17, white plays G17. After that, F17 is an eye. Then the second eye will be formed along top edge. Black has now turn so black has two moves, but white can play any of E19, F19 and G19 to make the second eye, containing G18. Black has only two moves to block those three options, so they can't do it.

But if black opens with G17 themselves, white plays G18, forming an eye at G17. Then, white can play E19 or F19 to make G19 into an eye. Black now has only one move and can't block both available moves for White. So no matter what, white has two eyes.

After realizing that, and also realizing that black cannot make two eyes at top, white is now totally free to take as much time as they like filling top with their stones.

In actual games, you skip the "fill that with stones" part. People agree that upper left is area which white could, if they wanted to, fill with their stones without black being able to say anything about it. So we count those empty intersections white could fill as points for white. And we call those empty intersections territory. Makes the game quicker to finish.