Learning how to deal with the L-groups

billywoods · **#21**

PeterPeter wrote:

What memorisation technique worked for you?

Just reading. I also memorised the (simple!) L-groups. Here's a quick-and-dirty, detail-free introduction to the L-groups - if you do the reading yourself, I promise you you won't forget them! The simple L-groups are easy because there's very few ways in which white can kill, and very few ways in which black can live - the eyespace is small and there are no tricky shortage of liberty problems or anything like that. And, helpfully, basically the whole situation succumbs to the proverb "your enemy's key point is your own".

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . . . . . . . $$ | . . X O . O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

This is an L-group.

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . B . . . . . . . $$ | B . X O . O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . . . . . . . $$ | B B X O . O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

These are L-groups with two eyes. This is what black should be aiming at in all cases: the eyespace is very small, and the only way to make eyes is to make one in the corner, and one encircled by the rest of the group. Check that white can't kill either of these, and keep these diagrams in mind. In practice:

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ | . 1 . . . . . . . $$ | 2 C X O . O . . . $$ | . . X O . . . . . $$ | T X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ | . 2 T . . . . . . $$ | 1 C X O . O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

...it doesn't get them. In each case white is threatening to play at triangle and connect his stone out. But if black stops white coming out, white can play at circle to break the other eye if necessary.

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . . . . . . . $$ | . . X B O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . B O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

This is an L+2 group. Notice the role of the two marked black stones:

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . 1 T . . . . . . $$ | 2 . X B O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . 2 . . . . . . . $$ | 1 . X X O O . . . $$ | . . X O . . . . . $$ | T X X O . . . . . $$ | . B O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Now white can't connect out using moves around triangle any more, because of the marked black stones. Check for yourself that black has two eyes in both cases - his eyespace is bigger. White's next trick is to try to weaken one of the marked black stones and reduce black's eyespace:

Click Here To Show Diagram Code: [go]$$W 2 elsewhere $$ ------------------ $$ | . . . . . . . . . $$ | 3 . X X O O . . . $$ | . . X O . . . . . $$ | T X X O . . . . . $$ | 1 B O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$W 2 elsewhere $$ ------------------ $$ | . 3 T 1 . . . . . $$ | . . X B O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

In these cases, when white plays 3, the marked stones have been weakened, and triangle allows white to connect out. So black should protect:

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . C . . . . . . . $$ | 2 C X X O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | 1 X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . 2 . 1 . . . . . $$ | C . X X O O . . . $$ | C . X O . . . . . $$ | . X X O . . . . . $$ | . X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

The circled points are miai for two eyes for black. Check this. There are many more things for white to try, but they usually fail. The above discussion tells us what to do in the case of L+1 groups:

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . . . . . . . $$ | . . X O . O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | 1 X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . 1 . . . . . $$ | . . X X O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

In both of these cases, the position reduces to an L-group and black is dead. Check this.

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ | . 1 . . . . . . . $$ | C . X O . O . . . $$ | C . X O . . . . . $$ | . X X O . . . . . $$ | . X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$B $$ ------------------ $$ | . C . . . . . . . $$ | 1 C X X O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . O O O . . . . . $$ | . . . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

In both of these cases, black protects the weak side of the L+1 group that doesn't have a 'leg'. (Compare these diagrams to the L+2 diagrams where white played first, and effectively reduced the L+2 group to an L+1 group.) Check that, as before, the circled points are miai for two eyes.

Click Here To Show Diagram Code: [go]$$W $$ ------------------ $$ | . . . W . . . . . $$ | . . X X O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | W X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

By the way, this is an L+2 group that's been reduced to an L-group and is dead - just for comparison.

When there are hanes, descents, cutting points or weird bumps in the shape, read it out from scratch. When white or black plays something non-standard, read it out from scratch. But when you've memorised the basic sorts of things this shape can do, reading it out from scratch becomes much easier.

SoDesuNe · **#22**

I know that you wanted to make a point with the two vital points but the regular shape move for the L+2 group with this Hane by White is the following:

Click Here To Show Diagram Code: [go]$$Wc instead of 'a' $$ ------------------ $$ | . a . 1 . . . . . $$ | . 2 X X O O . . . $$ | . . X O . . . . . $$ | . X X O . . . . . $$ | . X O O . . . . . $$ | . O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

It's better endgame-wise (my reasoning ^^).

Click Here To Show Diagram Code: [go]$$Wc Tenuki (four points) $$ ------------------ $$ | . 6 5 O 7 . . . . $$ | . B X X O O . . . $$ | . . X O . . . . . $$ | 2 X X O . . . . . $$ | 1 X O O . . . . . $$ | 3 O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

Click Here To Show Diagram Code: [go]$$Wc (three points) $$ ------------------ $$ | . B . O . . . . . $$ | 2 . X X O O . . . $$ | 4 . X O . . . . . $$ | 3 X X O . . . . . $$ | 1 X O O . . . . . $$ | 5 O . . . . . . . $$ | . O . . . . . . . $$ | . . . . . . . . . $$ | . . . . . . . . .[/go]

billywoods · **#23**

SoDesuNe wrote:

I know that you wanted to make a point with the two vital points but the regular shape move for the L+2 group with this Hane by White is the following

Completely agree - my spoiler is only intended to be a brain-free way of getting a handle on the basics of the shape and telling whether you've lived or died at a glance, hopefully streamlining the process for Peter (who said he found it difficult). (It's how I initially rationalised the L-groups to myself, and it's very natural, I think.) I now find complicated lines easier to read precisely because I learnt what I wrote in my spoiler. I am no authority on L-groups!

PeterPeter · **#24**

I like the idea of escape routes for white. Thank you.

Phelan · **#25**

In my case, I memorize the sayings or phrases themselves, and the initial shape attached to them. When I see one of those shapes, I always read it to be sure, but the more you play such situations with the initial shape and saying/phrase in mind, the more you can focus your reading.

I've failed to kill some groups which should have died, and lived with groups I shouldn't, due to me or my opponents not being aware of the usual lines of play, but by reviewing them after each failure(or success), I started to remember some of the key points and lines of play.

I still don't know them all by heart, and don't even try, as I hate memorization per se.

Learning how to deal with the L-groups

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