[Study Group] Essential Life and Death Patterns

There are several essential life and death patterns that quite commonly occur in games, however can be quite tricky to master. I think knowledge and familiarity with many of them are vital (necessary but not sufficient) for becoming stronger (reaching shodan and beyond).

If you’ve never heard of patterns like L groups, L+1, L+2, J groups, J+1, tripod, notcher, long L, door group, hovercraft, carpenter’s square, etc, and you are a DDK working toward SDK, or even an SDK working toward dan, then I think the below linked resources are valuable.

You could also figure out a lot of these patterns on your own by solving enough tsumego, but I think at least for some, systematic study could be beneficial. There are definitely many other great resources, but here are a few that I know about and found to be helpful.

1. Sensei’s Library

Sensei’s Library has a great catalog of common life and death shapes:

https://senseis.xmp.net/?LifeAndDeath

In particular, see the “Corner Shapes” and “Side Shapes” sections.

2. “Life and Death” book by James Davies

James Davies wrote a nice book called simply “Life and Death”. Each chapter focuses on a pattern or concept, spends a couple of pages discussing it, and then provides about six problems to further explain and explore variations.

https://senseis.xmp.net/?LifeAndDeathTheBook

3. Video by Haylee (Lee Hajin)

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Thank you 1001 times, @yebellz.

P.S.: Take a look at Jasiek’s First Life and Death.

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Perhaps a fourth way to systematically learn these patterns:

4. Participate in the study group formed in this thread

How about once a week I post in this thread one of the corner patterns, linking the Sensei’s library page and some problems to consider, and then we (for anyone that’s interested in participating) read the materials and work through understanding the pattern and problems together?

I’ll start this with my next post in this thread (either later today or tomorrow, to give me some time to gather materials), with the first topic being the “L group”.

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Week 1: The L-group (is dead)

Alright, let’s kick off this study group by looking at the L-group, which I think is a good place to start, since this pattern is very fundamental to understanding and evaluating other patterns.

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Sensei’s Library: https://senseis.xmp.net/?LGroup

Cliff Notes:

  • Black is dead (even if it is black’s turn to play)
  • “L-group is dead” is a proverb to remember, since other positions can be reduced to the L-group
  • However, still need to be able to read out how to kill under various resistances by black, and for some variations on the concept
  • Still dead even in variations with hanes

Problems from Sensei’s library:

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Ah-oh. I’m in trouble. I have learnt this one in this past… and then forgotten it… and then learnt it… and then forgotten it again. :confounded: So when it comes up in games I am working it out fresh each time, though I’m confident I usually get it right.:persevere:

Is it called the ‘L-group’ because of how it looks in this configuration?

LGroup

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Check out https://senseis.xmp.net/?TableOfNotchers

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Yes, I believe it’s called the L group because it looks like an L in that orientation.

The basic thing to remember is that black is dead even if it is his turn to play. You don’t have to memorize every response to black’s futile attempts to live, but just practice related problems enough that you can read it out during a game.

It is fundamental since some related groups can be reduced into an L group in order to kill. As the defender, you need to avoid being reduced to this dead shape.

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Here is a list with Sensei’s Library links for the corner shapes covered In the video by Haylee that I shared above:

  1. L-group
  2. L+1 group (first type, wider)
  3. L+1 group (second type, longer)
  4. L+2 group with a weak leg
  5. Hovercraft with descent (scroll down on this page)
  6. Unknown name?
  7. Unknown name? Discussed here: Puzzle from a recent game. Black to kill
  8. Long L group with descent
  9. Unknown name? Looks like an incomplete long L
  10. Unknown name?
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Week 2: Rectangular Six in the Corner

I originally considered looking at one of the shapes related to the L-group for this week. The shapes listed under that link are slightly more complex descendants of the L-group, since analyzing them often makes use of what we’ve learned about the L-group (i.e., that it is dead).

However, before we move onto to those, I thought it might be worthwhile to look at another related shape (although it is more like a sibling to the L-group), the “Rectangular Six in the Corner”:

zero one two

Sensei’s Library: https://senseis.xmp.net/?RectangularSixInTheCorner

Summary Notes:

  • Life and death status depends on the number of liberties
  • Zero liberties: unsettled, black lives by playing at a or b, white kills by playing at a
  • One liberty: white can play at a to create an approach ko
  • Two liberties: black is unconditionally alive
  • Looks like an L-group, but with two descents closing off the corner space

Problems from Sensei’s Library:

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Week 3: L+1 Group (first type, “wider”)

L%201%20wider

Sensei’s Library: https://senseis.xmp.net/?L1Group#toc1

The L+1 group is a direct extension of the L group. There is an extra stone, giving the group a “leg” to stand on. The leg could be on either side, so there are two varieties. The above pictures and focus for this week is just one of the those varieties, which I am calling “wider”, since it makes the L group larger along the shorter dimension.

Summary: unsettled (white can kill, black can live).

Here are four interesting figures:

  1. The most straight forward way for white to kill is simply hane to kick out black’s leg. This reduces the shape to the basic L-group, where black is dead. Any resistances by black are answered the same way as for the L-group.
    1
  2. White can also kill by playing inside at black’s vital point. This continuation reduces it to a bent four in the corner, where black is dead.
    2
  3. If it is black’s turn, black can play on the vital point to secure life. The extra leg stone let’s black focus on making two eyes with move 3.
    3
  4. Here is the corresponding continuation under the original L-group. Note what a difference the leg makes.
    4
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Week 4: L+1 Group (second type, “longer”)

L%201

Sensei’s Library: https://senseis.xmp.net/?L1Group#toc6

Summary: unsettled (white can kill, black can live)

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Week 5: L+2 Group

Sorry, it’s been a bit longer than a week since the last post.


Sensei’s Library: https://senseis.xmp.net/?L2Group

Summary: alive

Hanes might threaten to reduce this shape to a dead shape, but each can be correctly answered with inside play in order to secure two eyes (marked with circles).

The L groups

This shape wraps up a main theme seen from the L group, through the L+1 groups, and onto the L+2 group:

  • With no legs (L group), you are dead.
  • With one leg to stand on (L+1 groups), things are unsettled and you need initiative in order to live, before your last leg is kicked out from under you.
  • With two legs to stand on (L+2 group), you are alive.

Of course, there are a lot of complications along the way, with variations to each of these shapes.

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