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Approaching ALife And Death Problem The Right Way
Path: LifeAndDeath   · Prev: EternalLife   · Next: LifeAndDeathTheBook
Path: GoodHabits   · Prev: AnalyseTheGame   · Next: EstimatingTheScore

   

You know when you are dealing with a life and death problem if you ask yourself either one of the following questions:

  • Can I kill his group?
  • Would there be a way she can kill my group?

In order to answer these questions, it is a good habit to work systematically through all the possible moves that may work. I seem to recall it was some Kobayashi Koichi book or article that recommended the following order:

Isolate the group from the center

If the group still has access to the center, it has a possibility to link up to friendly forces.

Reduce the eye space of the group under attack

The classic example is a hane, hence the proverb that there is death in the hane.

Look at the cuts

If there is a defect remaining in the group under attack, it may become a good deal easier to kill it if you manage to divide it into separate pieces.

Placements

The rationale is that the placement will mess up the shape of the group under attack. However if you start with this technique, the group under attack may still have options of running to the center or becoming a bigger group, i.e. a group with more space to create eyes. This is why you should first look at isolating it and reducing the eye space.

--Stefan


The professional approach vs the amateur approach

To solve tsumego or real game problems, there is the professional approach as opposed to the amateur approach.

Amateurs have more or less the following approach:

Suppose we are to solve a tsumego

  1. We look for the vital point
  2. We look for a sequence, including the vital point, that kills or makes life
  3. If we have found a sequence, we verify the branches of that sequence to see if it really works
  4. We take that sequence as the solution

In a real game, when our group is threatened, it goes something like this

  1. We try to decide whether the group lives
  2. If it lives, we mostly leave it
  3. If it can live, we mostly play at the vital point in order to live
  4. If we are not sure about its status, we mostly add an extra defensive move
  5. If we have left it, we regularly come back to the problem to verify its status

The professional approach is very different, or so I have been told

Suppose they are to solve a tsumego. They

  1. Take all possible moves into account, starting with the one most likely to be the best (the vital point)
  2. Explore each move, with all of its branches, successively, and evaluate the result (life/death, points gained, remaining aji, sente/gote)
  3. Take the sequence with the best result as the solution

In a real game, when their group is threatened, they

  1. Take all possible moves into account, starting with the one most likely to be the best (the vital point)
  2. Explore each move, with all of its branches, successively, and evaluate the result (life/death, points gained, remaining aji, sente/gote)
  3. Measure the local result against the global position

For one thing, professionals have exactly the same approach to tsumego as to real game situations. For another, a professional reads until he knows exactly what is going on (locally) and knows the meaning of each move in each of the branches. Finally, once the problem has been read out, a pro never returns to verify the status. He'll only continue to perform the third step (weighing local result/global position) regularly.

We could try at least the professional approach in tsumego. If you continue to explore each possibility, even if you have found a solution, then you'll be surprised to find sequences that do the same thing as the one you already found, but with a better result in terms of points or aji. Moreover, exploring all moves, also the ones that don't work, does a great deal to your reading skills and your knowledge of shape.

--DieterVerhofstadt


Charles Matthews In real life, there is even more involved. There is a proverb about playing forcing moves before living (they may not be sente later). And there is a possibly conflicting piece of advice: live in a way that improves the position on ko threats. It is even possible that you deliberately live in a way that allows seki later, for the sake of other aji. This came up in a famous consultation game where Kitani and Go Seigen made up one of the teams.


A systematic way to solve life and death problems is as follows. If the problem is to live and not just a liberty race, then ask the following questions.

1) Is there and Eye Point inside. 2) Is there a point that divides the area into two rooms 3) Expand your eye space to get more room.

At each step of the process start at 1) and work your way down until the problem is solved.

An example

[Diagram]
Diag.: The Problem (1121 from Go Problems)

[Diagram]
Diag.: an eye point,

2 is also an eye point, but white plays 3 and it's ko. so let's change the last move that got us to ko. There is no point inside that divides the area to live in, into two rooms, so we skip step 2 and move on to step 3. Expand the eye space.


[Diagram]
Diag.:

But there's not enough room to live. So we've exhausted the steps, and need to fix the first move. There is no other eye point, so we choose a spot that divides the inside area into two rooms.


[Diagram]
Diag.: Divide into 2 rooms

Both 1 and 2 are eye points, so black gets one of them. and will live.


[Diagram]
Diag.:

White can try some squeeze plays as well, but we found the important points rather quickly to solve this problem. The hardest point in a life and death problem is when you need to expand your eye space. A few tricks are necessary for that.

If the puzzle is to kill then use these steps instead.

1) Is there and Eye Point inside. 2) Is there a point that divides the area into two rooms 3) Squeeze the eye space to give him less room.

The hard part about killing is seeing how to squeeze best. Sometimes it involves very clever sacrifices

JoeSeki



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Path: GoodHabits   · Prev: AnalyseTheGame   · Next: EstimatingTheScore

This is a copy of the living page "Approaching ALife And Death Problem The Right Way" at Sensei's Library.
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