This EPUB is provided without Digital Rights Management (DRM), allowing you to read it on your EPUB reader of choice. We trust that you use this EPUB file for your personal use only. Buying the book at gobooks.com ensures that authors and publishers get paid, and makes it possible for us to convert more books to digital format.

This EPUB contains static go diagrams only. This makes it compatible with more EPUB readers, but does not show the full potential of interactive Go Books. Get a download link for the interactive version at gobooks.com/support.html.

To make sure the solution diagram of a problem is hidden, switch to a view that shows one page at a time (e.g. portrait layout).

© 2015, Thomas Redecker, Berlin.

Igo Hatsuyōron 120 – An Elephant in Slices

Thomas Redecker

Buy the full book at gobooks.com

The most difficult of all Go problems, created by Inoue Dosetsu Inseki (1646 – 1719), has still not been solved by professional Go players.

“How do you eat an elephant?” is the usual management consultant’s reply, when being asked how to manage a project that is much too large to be treated as one single entity.

This book comes across with 120 slices, cutting down the problem in size.

We present, and explain, many small aspects of Igo Hatsuyōron 120 as (more or less simple) individual problems. Hopefully, this will make the reader fit to put together the entire puzzle on his own (to be honest: with some assistance, of course) in the very end, i.e. solving the most difficult problem ever.

Copyright Page

Great works are performed, not by strength, but by perseverance; yonder palace was raised by single stones, yet you see its height and spaciousness. He that shall walk with vigour three hours a day, will pass in seven years a space equal to the circumference of the globe.
(Samuel Johnson, 1709 – 1784)

According to Japanese customs and the usual order in East Asia with names of persons, we will always list the family name before the given name.

First edition.

© 2015, Thomas Redecker, Berlin. All rights reserved.
This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a book review or scholarly journal.

Email: igohatsuyoron120@gmail.com

The board graphic for the book cover was created using Multigo.

The Menu.

How Do You Eat an Elephant?

Introduction.

From the “Simple” Seki to the “Classic” Hanezeki.

The chapters in gray are included only in the full book.

From the “Classic” Hanezeki to the Main Theme of Igo Hatsuyōron 120.

The Road to Perfection.

The Growth of the Hanezeki’s Tail.

The Nakade on the Left Side.

Endgame in the Upper Right Corner.

The Keystone.

Endgame in the Lower Left Corner.

Endgame in the Upper Left Corner.

The FINAL Problems.

Some Side Dishes.

– Black’s final move in the Crosscut Sequence.

– White Plays Elsewhere After Black’s Guzumi.

– Joachim’s Ko-Semeai.

– Joachim’s Ko-Semeai (II).

– The Missing Black Stone.

The Eaten Elephant.

One Mystery Remains.

Some More Recommended Restaurants.

Some Notes About the Master Chefs and Other Kitchen Staff.

Some Notes About the Main Ingredients.

Summaries.

Warming Up

Warming Up (II)

Before the Start of the Road to Perfection

The Road to Perfection – Start

The Road to Perfection – Checkpoint Alpha

The Road to Perfection – Checkpoint Bravo

The Road to Perfection – Checkpoint Charlie

The Road to Perfection – Checkpoint Delta

Counter-Intuitive Features

The Road to Perfection – Checkpoint Echo

Counter-Intuitive Features (II)

Excursus.

Excursus I – The World of Tsume-Go.

Excursus II – Diamond and Diamonds.

Excursus III – Reverse Engineering.

Excursus IV – Approach-Move Liberties.

Excursus V – Dosetsu’s Genius.

Buy This Book

About Go Books

How Do You Eat an Elephant? – Introduction.

When we ask a management consult how to manage a project that is much too large to be treated as a single entity, they may say that this is similar to asking the question “How do you eat an elephant?”.

The simple, common sense, answer is “In (small) pieces!”, or “In slices!”, dependent on the dinner preferences of the management consultant asked. The advice given tells you to cut your tasks down in size.

Igo Hatsuyōron 120 is the most difficult Go problem ever created (by Inoue Dosetsu Inseki, 1646 – 1719), and even professional Go players must invest a large amount of time to really understand it. The first professional attempt to solve the problem known to us was published by Fujisawa Hideyuki 9p in 1982. Since then, especially Cheng Xiaoliu 6p worked on the problem, but none of these attempts could withstand determined questioning.

Together with Joachim Meinhardt, and Harry Fearnley, I have worked on Igo Hatsuyōron 120 for over a decade. We have published a few books so far that deeply analysed, and described, the whole picture, starting from the problem’s set-up. However, due to the various inter-dependencies in the problem, and the largely delayed onset of effect of several moves, understanding may be very difficult for the usual reader (i.e. an amateur player). This seems to be true, despite our various attempts to provide a lot of different, and extended, explanations of the main crucial points of the problem.

Recently, Harry Fearnley came up with the idea to present the problem, as well as the problem’s solution, as a kind of a “jigsaw puzzle”. He asked, whether it might be possible to extract, present, and explain, many small aspects of Igo Hatsuyōron 120 as (more or less simple) individual problems. Thus making the reader able to put together the entire puzzle on his own (to be honest: with some assistance, of course) in the very end, i.e. solving the most difficult problem ever.

Ideally, the puzzle would be so designed to have exactly 120 pieces.

Here comes the result of our efforts, and we hope that you will enjoy it! I am delighted that Harry Fearnley polished my English, as usual, to make the book more readable for native speakers.

During the course of the book, we will also present our idea of the (fictive, as a matter of course) chain of thoughts that might have motivated Inoue Dosetsu Inseki while creating his masterpiece.

Please be prepared for the fact that – in this context – some of the single problems presented might be trivial for you, and much below your level, especially in the very beginning of the book. However, in our opinion, even these seemingly too simple problems are needed to create a self-contained presentation of the whole story.

If you have any questions, or suggestions, please do not hesitate to e-mail us via

igohatsuyoron120@gmail.com

Berlin, February 2015
Thomas Redecker

How to Eat an Elephant? – From the “Simple” Seki to the “Classic” Hanezeki.

"Seki“ means ”shared life“, or ”mutual life".

Seki is a special configuration that has fascinated Go players since ancient times.

In its “simple” form, with one group of each colour, the two empty points that secure life for each group are not forbidden to the opponent by the rules, but by practical considerations only. Neither side may occupy any of these empty points without being captured by the opponent thereafter.

In its more complex forms, with more than one group each, neither side may capture any of their opponent’s stones without losing more points than they gain.

In this section, we will retrace the path from the “simple” type of a seki to a very special one that possesses a group, which is under permanent atari, but must not be captured by the opponent, and which is the starting point for the creation of Igo Hatsuyōron 120.

Problem 001

001

White to play.

Answer to problem 001.

001–01

W 1 occupies an outside liberty of Black’s group in the corner.

White’s three, and Black’s four, stones in the corner share two liberties, A, and C. Neither side is able to occupy either of these shared liberties.

A move at A – by either side – will be self-atari, so the opponent will capture at C with the next move. And vice versa.

The resulting shape – two groups with no eyes that share two liberties – is the basic case of a seki.

(Japanese Go terms – like “seki” above – are explained in the back of the book. With their first appearance, you will find a direct link to the explanation.

We ask for your kind understanding that we will use more Japanese Go terms than you might be accustomed to in English Go books nowadays. Igo Hatsuyōron is a Japanese classic; and in its problem 120, there are several key moves that are essential for either the solution, or important sub-variations. We prefer to highlight these very special moves by using their original Japanese name.)

Problem 002

002

White to play.

Answer to problem 002.

002–01

W 1 occupies a liberty of Black’s group in the corner, and simultaneously secures an eye for White’s own group.

Either side has an eye o of the minimum size; both groups in the corner share one liberty, A, and so have two liberties each.

Again, neither side will play the suicidal move of A.

The resulting shape is the basic case of a seki that has both sides with a one-point eye, combined with a shared liberty.

Problem 003

003

White to play.

Answer to problem 003.

003–01

W 1 occupies a liberty of Black’s group in the corner.

Both sides have an eye o of identical size – in this case, with a three-point nakade. Neither side is able to play at A.

The resulting shape is a seki with both sides having a larger eye of the same size – i.e. with the same number of internal liberties.

003–02 ( 0 3)

Capturing White’s three stones will not benefit Black.

003–03 ( 3 3)

W 3 takes the vital point of Black’s shape, so Black is forced to give atari with 4.

(We display the numbers of captured stones in a diagram’s caption. “ x y” in brackets means that – at the end of the sequence shown – there are x black, and y white, prisoners.)

003–06

Black must pre-empt two eyes for White’s group with a move at 6, but W 7 gives atari, and wins the semeai.

Problems 4 to 6 are included only in the full book.

Problem 007

007-B

007-W

Case 3:
Both outside groups are vulnerable, so careful analysis is needed.

What is the status of the corner?

Answer to problem 007.

007-B01 ( 0 3)

Black captures White’s outside group, …

007-B08 ( 3 3)

… but is unable to save his own group on the bottom. White’s group has three liberties inside its eye, but Black’s group at left has only two liberties left.

007-W01

White cannot avoid losing her own group on the right edge, …

007-W07 ( 6 4)

… but will capture Black’s outside group on the bottom.

007-W10

The final result after Black played first.

007-B10

The final result after White played first.

007-Status

All marked stones are dead. All others live unconditionally.

White will capture more stones than Black, so she gains territorially in the forthcoming exchange that resolves the temporary seki.

Conclusion:

Surrounding groups must live to keep the seki stable.

Problem 008

008

White wants to capture all of Black’s stones in the corner.

How many liberties (x) does White’s marked group need to have if she is to succeed in any case (White to play)?

Answer to problem 008.

008–01 ( 3 0)

The worst-case scenario for White is “Black to play”.

008–09 ( 3 3)

008–12 ( 10 3)

B 15 could be an atari on White’s group on the right edge.

008-WAlive

Eight liberties for White’s upper group (w) = three liberties more than for Black’s left-hand group (b).

(In answers to problems that are similar to this one – searching for a currently unknown configuration of a special group, like here – we prefer to display the opponent’s moves, which are designed to occupy liberties of the special group in question, in an unaffected area of the board, in order to simplify the calculation of liberties.)

Problem 009

009

This is Gengen Gokyō’s (1349 Xuanxuan Qijing’s) classic problem (with colours reversed); taken from Go Seigen’s 1980 Japanese edition (Heibonsha; ISBN 4–582–80387–3).

Black to play.

Answer to problem 009.

009–01

Black ends in gote.

009–04

The resulting shape is the “classic” hanezeki, with Black’s hane in permanent atari (thus the name of the seki), and with one shared liberty (x).

We will investigate its features in later problems.

Problem 010

010

This is Gengen Gokyō’s (1349 Xuanxuan Qijing’s) classic problem “Battle of Strength” (with colours reversed); taken from John Fairbairn’s 2012 “The Gateway to All Marvels” (SmartGo Books; http://gobooks.com/books.html).

Please note that – compared to the previous problem – two white stones on the outside are not present here.

Black to play.

Answer to problem 010.

010–01

White is forced to answer Black’s hane with the somewhat restrained move of 2.

010–03

B 3 follows the book’s solution, occupying an internal liberty of White’s group in the corner. Black ends in sente.

010–05

Again, the resulting shape is the “classic” hanezeki, with Black’s hane in permanent atari, and with one shared liberty.

Recently, Harry Fearnley discovered that White’s missing stones on the outside (compared to problem 009) might be somewhat sub-optimal for the problem’s set-up.
The further sub-variations would reveal several important features of “hanezeki” that were intended to be developed in the following dozen problems. Therefore, we will postpone the continuation of this solution.

010–03v03

Harry suggests the solid extension of 3 on the first line, instead, for Black. The story will continue with some kind of “solid extending”, and “jumping” on the first, and second, lines. Finally, B 13 establishes the hanezeki in the corner, in sente.

Problem 011

011 ( 1 0)

We can safely assume that Inoue Dosetsu Inseki, who lived from 1646 – 1719, knew this classic shape of a hanezeki (the earliest Japanese version of Gengen Gokyō is known from the Kan’ei era, 1624 – 1643), so let us investigate the features of the final position.

Is it feasible for White to capture Black’s single stone?

Answer to problem 011.

011–02 ( 1 4)

011–03 ( 5 4)

011–06

NO!

Many more problems are included only in the full book. A few more follow to give you a taste of what’s coming.

Problem 033

033

White to play. What will happen, if Black’s upper surrounding group has six liberties only?

Answer to problem 033.

033–01 ( 6 0)

033–02 ( 6 4)

033–03 ( 9 4)

White continues occupying liberties, and does not play oki at A.

033–08 ( 9 12)

033–13 ( 18 12)

033–16

White: 18 + 12 = 30 points
Black: 12 + 15 = 28 points

Two points for White.

Conclusion:

This is the "Punishment Semeai“ (”White Lives – Black Dies“ / ”Black’s Disaster“). Black must not lose liberties unnecessarily, so getting below the ”Punishment Semeai Liberty Level" of seven liberties.

Problem 056

056

This is the relevant position (stones that are unnecessary here have been deleted) just before the finalisation of the hanezeki (without Black’s kikashi that will be played later in the solution sequence) in Igo Hatsuyōron 120. Please assume a strong black position in the marked area on the left side.

Your task: Run!

Black to play.

Answer to problem 056.

056–01

As we know already, White must not let the hanezeki’s tail get more that one effective outside liberty.

This means that White is not able to play a net, e.g. with 14 at 16.

Also, White cannot play 32 at 33 to stop the tail’s journey, as this will result in a ko that White cannot win.

Due to Black’s strong position in the marked area to the left, White cannot stop Black’s path e.g. with W 16 at 17. She will not survive Black cutting her line of stones at left.

Problem 060

060

Black wants to reduce White’s territory in the top right corner, but must be very careful not to lose any liberties of his large group.

Black to play. What is his first move?

Answer to problem 060.

060–01

The push from below carries the largest follow-up threat for Black!

060-W01

It destroys two points of White’s territory in sente.

Some Notes About the Master Chefs and Other Kitchen Staff.

Inoue Dosetsu Inseki
Born in 1646 as Kuwabara Dosetsu, passed away in 1719. Third (at that time) head of the Inoue House. Became Meijin Godokoro in 1710. Author of Igo Hatsuyōron (published in 1713).

Fujisawa Hideyuki 9p
Born 1925 June 19; passed away 2009 May 8. Also known as Fujisawa Shūkō. Became professional in 1943; 9p in 1963. Became Honorary Kisei in 1977, after winning this title for six times in a row. Found the first ever published professional solution.

Jeong SooHyun 9p
Born in 1956. Became professional in 1973; 9p in 1997. Dean of the Department of Baduk Studies at Myongji University, Seoul, Korea.

Michael Redmond 9p
Born 1963 May 25. Became professional in 1981; 9p in 2000. The first and only Western Go-professional to ever reach 9 dan.

Cheng Xiaoliu 6p
Born 1946 January 26. Became 6p in 1982. Author of two Chinese editions of Igo Hatsuyōron.

Ōhashi Hirofumi 6p
Born 1984 May 25. Became professional in 2002; 6p in 2013.

Yamada Shinji 6p
Born 1983 July 14. Became professional in 2001; 6p in 2012.

Harry Fearnley 2d Amateur
Lives in Oxford, United Kingdom. Is very fond of mysterious “beasts”, e.g. hanezeki. Specialises in studies of seki, especially hanezeki. Found the pincer attachment in the top right corner, and the circular hanezeki. (http://harryfearnley.com)

Thomas Redecker 1k Amateur
Lives in Berlin, Germany. Author of several articles about this problem in the German Go-Journal (= Deutsche Go-Zeitung) since 2005, and editor of the corresponding website. Found the guzumi in the top right corner, and the Double Throw-in.

Joachim Meinhardt 4k Amateur
Lives in Frankfurt/Main, Germany. Has studied the problem since 1999. Rediscovered the decisive oki in the lower right corner, putting the so far known professional solutions into question. Found the very complicated ko-fight variations.

Some Notes About the Main Ingredients.

General Terms

Atari

atari

The state of a stone or a group (), which has only one liberty (x; and could be captured by the next move). Very often used for the move itself – which takes the last but one liberty (B 1).

Attachment

attachment

A single stone which is played in immediate contact with an opponent’s (often single) stone.

Bamboo Joint

bamboo joint

The shape of the four black stones after Black played B 1. It is normally impossible to cut through this strong connection.

Cut

cut

A move that separates opponent’s groups () in conjunction with another one of its own, diagonal adjacent, stones ().

Descent

descent

A move like B 1, which descends towards the edge of the board.

Double-Ko

double-ko

Two ko, happening simultaneously in the same fight, and serving the same purpose. If one player captures the first ko (here with B A / B 1), the other player captures the second ko (with W C / W 4). Can become a large supply of ko-threats (here for Black), if there is another ko on the board.

Drawing Back

drawing back

A move, which connects an endangered stone (loosely) towards own stones.

Flower Viewing Ko

flower viewing ko

Or “picnic” ko. One side has almost everything to lose (or much more than the opponent), while the other stakes almost nothing.

Gote

Losing the initiative. A move, which need not be answered.

Guzumi

guzumi

Good bad shape. A shape (usually an empty triangle), which looks bad, but is good, and effective, in the local context.

Hane

hane

A diagonal move played from one’s own stone, in contact with and around an opponent’s stone. Often facing the edge of the board.

Hanezeki

hanezeki

A seki (    ), in which each side has a chain in atari ( ), which must not be captured. Otherwise the loss will be greater than the gain.

Hanezeki’s Tail

hanezeki’s tail

If the external part group of the hanezeki () that includes the “hane”, consists of more than one stone, then we call this the “hanezeki’s tail”.

Kikashi

kikashi

Forcing move. A sente move, which often has some additional effect that might be used later. Often played outside the main flow of play.

Ko

ko-rule

Shape, in which the rules prohibit the immediate capture of a single stone (W 2) that has just captured a single stone at the prohibited point (K).

Miai

miai

Two options with the same value, or purpose. If one player takes one of them, the other one is left for the opponent (who is often forced to play there).

Nakade

nakade

Large shape (x), which can be reduced to only one eye.
Also used for the move that takes the vital point of such a shape (B 1).

Net

net

Capturing by blocking the possible exits.

Oki

oki

Placement. A stone placed inside an opponent’s group, often on a vital point.

One Eye Vs. No Eye

me-ari-me-nashi

Capturing Race, wherein one side () has an eye, the other () hasn’t.

Pincer Attachment

pincer attachment

Clamp. A move, which attaches to an opponent’s stone, and at the same time, pincers that stone.

Seki

seki

Mutual life, shared life.
A configuration where groups of both colours share liberties, and are not independently alive. Neither side may capture any of their opponent’s stones without losing more points than they gain.

Self-Atari

self-atari

Adding a stone to one’s stone or stones that are not in atari, with the result that these stones are in atari.
Most often the self-atari is a mistake or a blunder; accidentally, it even happens in professional play.
After the self-atari of 1, White can capture five stones with A.

Semeai

“Capturing Race”. Fight for life and death, usually involving only two groups.

Sente

Initiative. A move, which is answered.

Shortage of Liberties

shortage of liberties

For example, Black cannot play at A, to secure two eyes for his group, without putting his own stones () in atari.

Tail

See “Hanezeki’s Tail”.

Tesuji

A skilful move that is the best play in a local position.

Throw-in

throw-in

An aid to killing, or capturing using a sacrifice stone, which results in a false eye shape (x), and which is often used to prevent the opponent from connecting at that point, or to reduce eye-space.

Tsume-Go

The field of “Life & Death” problems.

Under the Stones

under the stones

A tactic involving the sacrifice of a group of stones, usually to secure – or to destroy – an eye for an endangered group. For example, B 3 plays under the stones .

Announcement

Get the whole story in two volumes. Over 1.000 pages in the hardcover edition!

– Our solution to the problem.
– Explains the general structure of the problem in large detail.
– Contains a large amount of variations.

– The professionals' solution to the problem.
– Contains all the variations that are known to us.
– Gives deep insights into the ups, and downs, of our research.
– Explains several structural elements of the problem in great detail.

The fourth edition of our in-depth analysis is planned to be published in 2015.