# How to protect a large piece of side territory

I've played several games where I have gained a good chunk of side territory, but lost it due to invasion by the other player.

Below is an example, ignore the placement outside of the area black surrounds and focus on solving the problem inside.

``````\$\$ Defending the side
\$\$ .............
\$\$ .....OOOOOOO.
\$\$ ..XXXOOXOX.XO
\$\$ OOX..XX.X.X.O
\$\$ OX.....X...X.
\$\$ XX.........X.
\$\$ X..........X.
\$\$ -------------
``````

White has several points of injection, what would be some good strategies to make any attempt at minimizing or taking away this territory fruitless.

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You can now use SL-style notation to get boards, there's no need for screenshots anymore :) You can read some details here. – Adrian Petrescu Nov 11 '11 at 21:46
@Paul, what is your level in Go? So I know how to direct the answer – mafu Nov 11 '11 at 21:48
@mafutrut I have a 4 stone handicap in this instance, I'm not sure if there is any other indicating my level. – Paul Nov 11 '11 at 22:01

## 3 Answers

The answer is: Don't, unless you really have to.

The situation shown in your question is already solid territory. In this case, adding any inside stone to "protect" your territory further will reduce your score.

You should try to decide if there is anything that can be exploited in your area. Let's see how it is in your case:

``````\$\$ Initial position
\$\$ .............
\$\$ .....OOOOOOO.
\$\$ ..XXXOOXOX.XO
\$\$ OOX..XX.X.X.O
\$\$ OX.....X...X.
\$\$ XX.........X.
\$\$ X..........X.
\$\$ -------------
``````

As a simple rule of thumb: Imagine your opponent playing all inside forcing moves in sente, then try to find the vital point. Is there a way to live?

``````\$\$Wcm1 Is there a way to live? Even if black plays very simple, white cannot do anything after B10.
\$\$ .............
\$\$ .....OOOOOOO.
\$\$ ..XXXOOXOX.XO
\$\$ OOX.0XX6X4X8O
\$\$ OX219..X537X.
\$\$ XX.........X.
\$\$ X..........X.
\$\$ -------------
``````

If not — as in this example — do not add stones. If you are unsure, it is good practice to still play away (this is vaguely related to the concept of kiai). As sole exception, if you're far ahead and it's an important game, well, I suppose you may add an inside move to make 110% sure.

Of course, sometimes you do have to defend without question. Usually, you should try to defend actively, by moving out or attacking a weakness of your opponent's stones to make your own stones more secure. If that is impossible, simply add a move at the vital point.

Where is the vital point? Shape sense will tell you. Around 10 kyu you should see spots that defend most or all weaknesses. Until then, there is no recipe, so just keep playing until you've built up enough experience.

Again, as a rule of thumb, try to fix potential cuts, make sure every part of your group has enough eyespace or is solidly connected. If the inside area is very large, play somewhere in the center to make divide the potential invasion space in two fractions, each too small to do anything.

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I use what I call the "three cut point" rule. That is, my position is in danger if there are three cut points close to each other.

For the time being, your position is "safe." There are only two cut points on the left side.

The main danger comes if white takes the ko. That potentially creates a bunch of other cut points. With the move, I might consider filling the ko and eliminating this aji. If white took the ko, I might connect at one of the cut points, and let white fill the ko.

The other danger is that White will play a insertion move on the right side, "forking" two Black stones. The one nearest the edge is a stray stone and can be given up. The one more toward the center needs to be protected, because losing it would create more cut points.

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Defending a large chunk of territory is not easy, that's why the 3-3 point is highly regarded.

In your position, the main weakness is at 2:

``````\$\$ .............
\$\$ .OOOOOOOOOOO.
\$\$ .OXXXOOXOX.XO
\$\$ OOX.8XX.X.X.O
\$\$ OX246..X...X.
\$\$ XX35.7.....X.
\$\$ X..........X.
\$\$ -------------
``````

Note that you can't completely ignore what is going on on the outside - I have added surrounding white stones.

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