: Moon yong-jik 5p's explanation of sequence dissection(tewari)
(2007-08-11 22:59) [#3751]
I translated a part of Moon 5p's book 'Discovery of Padook'(some pages in the chapter 1 of part 1 of the book).
In the pages, he explains about sequence dissection with several examples. I hope it would be helpful for understanding sequence dissection better.
Beginning of Dosaku revolution: Doseki, Sequence dissection(手割論)
A great Go master, Inoue doseki (道碩, 1582-1630), who lived at the dawn of modern Go era before Dosaku, deserves his eternal fame in Go history. Itís because he invented ĎSequence Dissectioní(手割論). Sequence dissection made a great contribution towards the development of modern Go, its value is still valid up to now and it was also the beginning of the revolutionary advancement of Go by Dosaku.
Sequence dissection can be defined as ĎA method of examining efficiency of moves (in a sequence)'. It does so by comparing the sequence to another sequence, but ignoring specific move orders. It is a method to help us to check(judge) goodness of a specific sequence played on board. It is not a limited tool which can be applied only to a specific stage of a game, for example, applicable only to middle or opening stage of a game. The use of this method is valid in all stages of a game of Go.
Definition of Sequence dissection: A way of judging efficiency of moves in a sequence by comparing it to another sequence, but ignoring specific move orders of 2 sequences
First, I hope you to follow an example of Sequence dissection. (Diagram 20-1, 20-2)
corresponds to Black move 82 in the actual game. Position is taken partly from the entire game position. is interesting. Is it a bad move? No. Itís inevitable that black retreated with (Next diagram shows why).
From ordinary amateur playerís view, It may look like both black and white give way to each other, thus you may think that both fabricate a weird sequence(underplay) on purpose. But there is an inevitable(necessary) reason for this sequence.
If black fights resolutely (instead of in previous diagram), sequence on the top left corner is necessary and inevitable. Superficially, It feels happy for black, capturing 6 white stones. But is it really so? Position on the bottom right corner shows the end result. And position on the top right corner shows a position in which we take off the same number of black stones as the number of the captured white stones. Black has just 18 points. Just 18 points with 11 black stones! White makes iron wall with 11 stones. The center, wide as heaven and earth, covered by white snow
Diagram 21-1 is an example which dosaku showed in 17th century. I recommend you to follow my comments on diagram 21-1~4 as previously, to see how sequence dissection is useful. Joseki sequence in the bottom right corner of diagram 21-1 appears already in a time of the first honinbo sansha(算砂, 1559-1623) and doseki. But the meaning of the sequence was understood only after Dosakuís Go revolution. In fact, we sometimes see a sequence of Go technique from an ancient Go game record, which has identical shape and sequence with that of contemporary top level professional players. Are they the same ones? Though you may think that they are the same ones because of the same shape its sequence, the answer is ĎNoí. Itís because the understanding of the sequence, and the basis of explanation of it, and the reason of playing it is completely different, even though the apparent shape itself is the same.
Sequence from white 12 to black 25 on the bottom right corner is a joseki. But, does this joseki make sense in this context? How can it be judged? The answer lies in its relation to black 9 on the bottom left corner. Notice that white induced the joseki sequence on the bottom right corner, after making a move exchange of white 10 and black 11. Then we can see that white is aware of relation between black 9 and the joseki on the bottom right corner, but black is mindless of it.
Letís see the meaning of it in the following diagram.
We take off Black9, white 10, and black 11 from the previous diagram.
In this context, is black ĎAí a good move?
The answer is ďNoĒ.
If black plays here, Black B or Black C is recommendable. Since black already has a solid position on the bottom right corner, Black A improves blackís position on the bottom side just a little and there wouldn't be much difference even if black A would have been omitted
Therefore, we can find a solution now. Remember the first diagram. Taking a position on the bottom left corner into consideration, Black should turn his hand(play) to the bottom left corner with , treating(handling) the bottom right corner area with a sequence from to in blackís sente. This turns the white stone on the bottom left corner into a nulltified and meaningless stone.
Letís see another similar solution.
Black can choose aggressive fight on the bottom right corner. Itís because the position on the bottom left corner is strong and advantageous for black.
Now, the answer is obvious. We can apply sequence dissection to opening. Then we can understand direction of stones in opening. We can also judge whether a joseki choice is appropriate.
Diagram 22-1,22-2 also shows how sequence dissection is used. Follow my comments on the diagrams, and you can see that the basis of evaluation of opening and joseki relies on Sequence dissection considerably. The following diagram 23-1 shows an example which occurs frequently in contemporary Go. Why should black emphasize the bottom side? The process of answering the question relies on sequence dissection a lot. Follow my comment on the diagram(diagram 23-2).
Before dosaku, understanding of sequence dissection was certainly poor. As a result, Go players were mindless of direction of stones, and their understanding of efficiency of stones was also poor. Sequence on the bottom left corner was a joseki at the time. Notice black 21(). we can see that black fails to avoid overconcentration. Speaking more correctly, black shows lack of training to analyze goodness of Go moves with sequence dissection.
Letís see the previous diagram again.
is a correct direction. It drives opponentís stones toward our solid position. Of course, itís not easy in practice.
This opening occurs really frequently in contemporary Go games.
Why does black not try to capture white 8 stone, by playing at the place of white 12 with black 11?
The answer lies in blackís move exchange with white 4 on the bottom left corner- , and .
Before proceeding to the next diagram, let me say just one more thing. Isnít the black moyo on the bottom side magnificent? The center is also wide.
What if black tries to capture the white stone on the right side with Black 1 move? Then, itís inevitable upto . what do you think about it?
Donít you think that the black stone (marked with circle) at bottom side hoshi is placed in an awkward way? Of course, this result is not so decisively bad for black. But, itís not as good as blackís moyo and expansion of bottom side in the previous diagram. In the beginning, black tried to put emphasis on the bottom side.
This way of thinking is an example of sequence dissection. Sequence dissection is very essential to judge opening, joseki choice, and direction of stones.
I wonder where the idea of sequence dissection came from.
In my guess, it may be that the idea of sequence dissection came from the rule of alternate turn to play, on the supposition that the winner is one who has more territory at the end of a game. It would be realized that while both black and white plays a move in alternate turns, if one of them plays a move at meaningless place to contribute an increase of territory, then it would result in territory damage eventually sooner or later. Therefore, the idea that in certain relation of stones of a Go position, some stones are necessary, but some stones are unnecessary (redundant stones), maybe it was the idea ultimately gained, I guess.