Mastering Basic Corner Shapes

Step-by-Step

by Young Sun Yoon

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Playing strength in Go rests on various pillars such as reading and evaluation ability, factual knowledge stored in our memory, and intuition. Reading ability is a most essential skill but, unfortunately, the most difficult to develop. It comprises the ability to visualize candidate moves and the power to read out correctly the relevant variation trees before making a decision.

Studying life and death problems that are not too difficult is unanimously regarded as the best way to develop and sharpen reading and visualization. It comes as no surprise that developing these skills lies at the heart of Go or Baduk education for children in Korea.

In the 52 chapters of this book and in the corresponding videos, an in-depth analysis of the most frequently occurring corner shapes as well as their origin is presented. Each chapter consists of four problems of varying difficulty that are usually based on the same basic shape. The majority of the chapters offers a step-by-step approach where an otherwise difficult-to-solve problem is deconstructed into two or three easier problems. The solution section analyzes the most relevant variations and failures, as well as typical mistakes by both players. Preferably, this book is used actively by laying out the problems on a board, and exercises to significantly reinforce the learning process are proposed.

These exercises might be time-consuming but they are of the greatest benefit and necessary to train not only your memory but also both your reading skills and visualization: In a life and death problem, ultimately, you need to rely on these active skills — not on passive knowledge.

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Copyright Page

Mastering Basic Corner Shapes
Step-by-Step

Copyright © 2024 by Young Sun Yoon

All rights reserved according to international law. This book or any parts thereof may not be reproduced in any form without the written permission of Awesome Baduk Corp.

Author: Young Sun Yoon
Co-author: Paul Schmit

Published by:
Awesome Baduk
Kyeong ki-do, GimPo-si, Jangki-dong 1642
GoChang, BandoYubora 905–302, Korea

Website: www.awesomebaduk.com
E-mail: contact@awesomebaduk.com
Discord: discord.gg/VWcQDrkr7b

ISBN of the printed version: 979–8–89587–633–6

Converted for SmartGo Books by John Mifsud.

Contents

Mastering Basic Corner Shapes Step-by-Step

Copyright Page

About the Author

About the making of this book

Introduction

How to use this book

Index of the problem chapters

Origin of the shapes

Chapter 1 — The basic L-shape

Chapter 2 — The L + 1 group

Chapter 3 — Step-by-step: L + 1 group + one Hane (I)

Chapter 4 — L + 1 group + one hane: Punishing mistakes

Chapter 5 — Step-by-step: L + 1 group + one Hane (II)

Chapter 6 — Step-by-step: L + 1 group + one Hane: punishing mistakes

Chapter 7 — L + 1 group + two Hanes

Chapter 8 — Origin of the shape: Where does the L + 1 group usually come from?

Chapter 9 — Step-by-step: Inside a modified Long-L group

Chapter 10 — Punishing mistakes attacking the modified Long-L group

Chapter 11 — The origin of this modified Long-L group

Chapter 12 — Step-by-step: The Tripod group

Chapter 13 — The Tripod group: Punishing the mistakes

Chapter 14 — Defending the Tripod group

Chapter 15 — Step-by-step: Avoid this liberty destroying exchange

Chapter 16 — Origin: Where does the Tripod group come from?

Chapter 17 — Step-by-step: Three liberties in the corner

Chapter 18 — Three liberties in the corner (Continuation 1)

Chapter 19 — Three liberties in the corner (Continuation 2)

Chapter 20 — Three liberties in the corner: Where can this shape come from?

Chapter 21 — Step-by-step: Corner shape arising after a one-space pincer joseki

Chapter 22 — Step-by-step: Corner shape arising after a one-space pincer joseki (Continuation 1)

Chapter 23 — Step-by-step: Corner shape arising after a one-space pincer joseki (Continuation 2)

Chapter 24 — Origin: Where does this shape come from?

Chapter 25 — Step-by-step: Put the screws on a group with two hanes

Chapter 26 — Origin: Where did this shape come from?

Chapter 27 — Step-by-step: When a hane is an awful mistake

Chapter 28 — Step-by-step: Hane is the simple way

Chapter 29 — Step-by-step: One-space jump to the first line!

Chapter 30 — Step-by-step: Spotting the vital point is not enough

Chapter 31 — Origin: Where do the shapes from chapters 27–30 come from?

Chapter 32 — Step-by-step: Do not give atari

Chapter 33 — Origin: Where does the shape from chapter 32 come from?

Chapter 34 — Step-by-step: The hidden move

Chapter 35 — Step-by-step: More variations of a basic corner shape

Chapter 36 — Step-by-step: How exchanging a hane saves the corner

Chapter 37 — Origin: Where did the shapes from chapters 34–36 come from?

Chapter 38 — Step-by-step: When a Small Monkey Jump is enough to kill an open corner

Chapter 39 — Punishing mistakes related to the monkey jump

Chapter 40 — Origin: Where did the shape in the previous chapter come from?

Chapter 41 — Step-by-step: More variations around the Long-L group

Chapter 42 — Origin: Where does this Long-L group come from?

Chapter 43 — Step-by-step: Resisting an invasion in an enclosed corner

Chapter 44 — Origin: Where did the shape in the previous chapter come from?

Chapter 45 — Step-by-step: Making use of a cutting point

Chapter 46 — Origin: Where did the shape in the previous chapter come from?

Chapter 47 — Step-by-step: More incomplete corner shapes

Chapter 48 — Origin: Where did this incomplete shape come from?

Chapter 49 — Step-by-step: How the cut reduces eye space

Chapter 50 — Origin: Where did the shape from the previous chapter come from?

Chapter 51 — Master bent-four in the corner 1

Chapter 52 — Master bent-four in the corner 2

Appendix 1 — Bent-four in the corner

Appendix 2 — The ten-thousand-year ko

Appendix 3 — Approach move ko

Appendix 4 — Neuroscience and Go

Buy This Book

About SmartGo Books

About the Author

Young Sun Yoon 8p, author

1992: Became professional at age 15

1994–1998: Won the Female Kuksu Tournament four times

2002: Won the Hojak Female World Championship

2003: Took 2nd place at the Jeongwanjang Female World Championship

2005: Graduated from Myong-Ji University as a Master of Baduk Education

1996–2006: Commentator on Baduk TV

2006: Published her first book Think like a Pro – Haengma and moved to Germany where she started to promote Go

2019: Opened her Youtube channel Yoon’s Baduk Café

2021: Launched the Go learning platform Awesome Baduk together with Yeonwoo Cho 2p

2023: Published book 1Dan Challenge

2024: Published book Typical mistake

Paul Schmit, co-author

1975: Started to play while studying medicine in Innsbruck

1993–1998: Participated three times in the World Amateur Go Championship in Japan as representative for Luxembourg

2006: Visited Kirina Baduk Academy for two weeks

2019: Retired as a urologist and is motivated to improve his current rank of 2 kyu EGF by two stones

About the making of this book

By Paul Schmit

When Young Sun Yoon informed me about her new book project, I proposed I help work out the annotations she had already made for every diagram and we discussed the result over regular Skype meetings. At an early stage already, I wanted to ask for the feedback of a highly competent player: Laurent Heiser, 6-dan, computer scientist from Luxembourg.

During his active time, Laurent was one of the strongest international amateur players. He participated multiple times in the World Amateur Go Championship in Japan, achieving 4th place twice, just behind the top Asian players and finishing six times among the prize-winning top eight.

Laurent was the instructor for multiple Go workshops mostly in France and Switzerland. He has a huge library of not only Go books in English but also many volumes in Japanese, Chinese, and Korean, making him not only a practical but also a theoretical expert on the game.

Laurent’s role became that of a critical consultant, not only detecting inevitable mistakes but he also suggested to look deeper into the variation tree of some shapes, by investigating them with KataGo. Laurent also suggested and guided the writing of the special chapters about the bent-four in the corner, the ten-thousand-year ko and the approach move ko.

While we were well into our project, I proposed Young Sun to also ask Rob van Zeijst, 7-dan for his opinion and travelled to Amsterdam for this purpose. Rob is a truly legendary European Go player: He won the European Championship three times, he was the European representative for the Fujitsu cup four times, and in international tournaments, he has defeated professionals up to 7-dan.

After moving to Japan, Rob started out teaching Go at Sakata Eio’s Go salon and became an Insei later but had to leave the league due to health problems. Rob lived and worked in Japan for more than 30 years as a technical translator and a court interpreter.

After his return to Holland in 2016, he started to teach Go at Dutch clubs and he is giving Go lessons online. Rob co-authored many excellent Go books with Richard Bozulich from Kiseido. Rob was very helpful giving advice about a suitable language style and he also did the final proofreading. Our many hours of discussions about reading and visualization were most useful for writing the introduction. Rob also contributed to the second, revised edition of this book.

Introduction

The idea for this book was born after the positive response to a couple of step-by-step videos in “Yoon’s Baduk Cafe” on YouTube: Young Sun got motivated to develop this concept and compiled the most essential corner shapes suitable for this project into the 50 chapters of this book. Its main purpose is not just to store the knowledge about these shapes in your mental library but also to help you train both your reading and visualization skills as nothing is more defining for your playing strength.

Each chapter consists of four problems, mostly of increasing complexity and usually based on the same basic shape. The majority of the chapters offers a step-by-step approach where an otherwise difficult-to-solve problem is deconstructed into two or three easier problems.

In these life and death problems, you will be reminded that it is mostly correct to reduce from the outside first. The tesuji that are used are most basic: the hane, the placement, the throw-in. Situations with a shortage of liberties occur frequently and you will also encounter a fair amount of ko fights — ranging from the very simple to the utmost difficult — as well as plenty of problems involving bent-four in the corner. Because of the difficulties encountered in these situations, three appendices related to the bent-four in the corner, the ten-thousand-year ko, and the approach move ko were added at the end of this book.

You are asked to work through the problems counter-clockwise: The first problem in the top right corner represents almost the end of the correct sequence, typically a few moves have already been played and the final answer is often quite simple. Problems 2 and 3 contain fewer hints, while problem 4 usually features the basic shape prior to the attack as it may appear in an actual game.

Because of the previous steps, the reader’s mind is now primed to find the answer rather quickly. An otherwise difficult 9-move problem has thus been deconstructed into two or three easier to solve problems. The solution section analyzes the most relevant variations and failures, as well as typical mistakes by both players.

After a shape has been studied in up to 6 chapters, a concluding chapter is devoted to its origin. If available already, a link will give access to the video about the relevant chapter, while videos about the majority of the chapters are planned.

This is definitively not a standard Life and Death problem book because you get plenty of help in a stepwise fashion to guide you to the correct solution. The presented shapes are so essential that they should be part of your Go knowledge. It is best to memorize them after studying and understanding the inherent complexities so that this knowledge is quickly made accessible by pattern recognition when the relevant shapes appear in a game.

Neuroscience has made significant advances in the fields of understanding expertise and learning. The last appendix of this book deals briefly with this topic and encourages readers to deepen their understanding and implement new learning strategies when studying Go.

How to use this book:

Preferably, this book is used actively by laying out the problems on a physical board. According to neuroscience, the more of the senses are involved, the more your memory is reinforced.

- It makes sense to start with the first eight chapters first as they deal with the very essential L-shape.

- The chapters about the origin of a given shape might be consulted and studied at any moment.

- Solve the problems in the order 1–4. Depending on your level, you might want to work out all the problems first but you can also check the answer immediately before moving on.

- Studying the variations and refutations of mistakes by both sides is as important as the primary solution.

- Don’t spend too much time on a problem. If you don’t advance in your reading and your thoughts are always jumping back to the beginning, it means the problem is too difficult for you. Study the solution and the variations and move to the next problem.

Korean kids who start with a structured training at a Go school develop reading skills naturally as they regularly have to solve a lot of Life and Death problems, first very easy ones and then with increasing difficulty. They do this when their neuroplasticity is highest: Reading and visualization develop naturally, almost like the acquisition of a native language.

The situation is very different for western players and their development often gets stuck because of poor reading skills, but there is a remedy for this: lots of not too difficult Life and Death problems and the motivation to overcome this situation.

Reading out a potential future variation is a complex cognitive task that starts easily like: I play here, he plays there, but already after the second or third move the thinking process might get fuzzy and you have to restart, eventually over and over again. Why? Because of an incorrect choice of candidate moves but especially because of the inability to visualize a resulting position. Without correct visualization, your desperate mind always slides back to the departure point. This makes a correct evaluation impossible.

Visualization and mental imagery constitute a huge field of research. It found application as mental training in sports. For example tennis players can train their serve while sitting on the couch, thus perfecting their muscle control. In another domain, a Go player could strengthen his cognitive skills by mentally rehearsing a joseki! Visualization can be trained specifically in mind games. There is an abundance of training material available in the form of books, software programs and YouTube videos. Unfortunately most are about chess, not about Go.

The topic of this book makes it almost ideal to propose exercises that specifically train your visualization skill:

- Start to visualize an empty corner, initially up to six horizontal and vertical lines.

- Try to see the 2–2, the 3–3, the 4–4, and the 3–4 intersections. These key points will help you to “stabilize” your mental image of a corner. Create different shimari, change the colors of the stones, make approach moves. Rehearse after you went to bed!

- Try to memorize the basic shape – usually problem 4 – and remove the stones from the board. Before you start putting stones back: Look at the empty lower right corner and visualize the shape without any stones on the board. Only in the next step you put the stones on the board, repeat until these steps are easily performed.

- Close your eyes and try to visualize the shape only before your mind’s eye, initially this is difficult but it can be trained.

- When you learned the correct solution, replay it mentally stone by stone with just the shape stones on the board.

- Visualize the solution with no stones on the board. Advanced visualizers should be able to replay the sequence on a mental board.

- Train to visualize and replay the basic shape and its origin in all the remaining corners. Getting out of your comfort zone really triggers neuroplasticity!

- Plan your own exercises: Replay professional opening, josekis etc…

If you realize that visualization is a skill that can be trained specifically, you are on the right track!

The last issue we have to talk about is memorization, if you want to improve any skill, you have to learn correctly in order to be efficient. You might have heard it before: Repetition is the mother of learning! Learning has to anatomically change your brain to be effective. Due to neuroplasticity, new memories are formed as neurons establish new connections. To strengthen these connections, repetition is mandatory otherwise the memory fades away. It’s use it or lose it!

Index of the problem chapters

Chapter 1

Chapter 2

Chapter 3

Chapter 4

Chapter 5

Chapter 6

Chapter 7

Chapter 9

Chapter 10

Chapter 12

Chapter 13

Chapter 14

Chapter 15

Chapter 17

Chapter 18

Chapter 19

Chapter 21

Chapter 22

Chapter 23

Chapter 25

Chapter 27

Chapter 28

Chapter 29

Chapter 30

Chapter 32

Chapter 34

Chapter 35

Chapter 36

Chapter 38

Chapter 39

Chapter 41

Chapter 43

Chapter 45

Chapter 47

Chapter 49

Chapter 51

Chapter 52

Origin of the shapes

Chapter 8

Chapter 11

Chapter 16

Chapter 20

Chapter 24a

Chapter 24b

Chapter 26

Chapter 31

Chapter 33

Chapter 37

Chapter 40

Chapter 42

Chapter 44

Chapter 46

Chapter 48

Chapter 50
13: elsewhere

Chapter 1
The basic L-shape

Watch Video

The L-shape is one of the most frequent, fundamental corner positions. With no opportunities to connect to the outside, the basic or small L-shape is locally dead.

Thorough knowledge of the different L-shape variations is essential to improve and speed-up your reading during a game and avoid the many possible pitfalls.

Learn to recognize the L-shape, also in incomplete patterns, and you will become a master of this shape.

In this first set of problems, White made four different attempts to live, but all are futile.

Problem 1–1

Black to play

Solution 1–1

Dia. 1–1 Placement

The easiest killing method is to play directly at the vital point, then reduce from the outside.

Playing at 3 first would also work.

Problem 1–2

Black to play

Solution 1–2

Dia. 1–2 Vital Point

Starting at the vital point is the only correct solution.

Problem 1–3

Black to play

Solution 1–3

Dia. 1–3 Hane

The easiest killing sequence for Black is to reduce first with 1 and then play at the vital point with 3.

Problem 1–4

Black to play

Solution 1–4

Dia. 1–4 Hane first

Reducing first from the outside and then taking the vital point with 3 is the best sequence.

In this situation, starting with 3 would also be possible, but in case of a capturing race it is necessary to start from the outside as inside plays generate more liberties for the opponent. Starting from the inside is a rather bad habit of kyu players.

Recap

- Locally the L-shape is dead

- The formation might still have a value for ko fights

- In case of a capturing race, the group has a lot of internal liberties

This 1–2 point would be the correct attack in a capturing race. Starting at A would be the worst mistake as White would get a five-space big eye resulting in eight liberties.

The capturing race is also highly dependent on outside stones, but developing all these complexities would go beyond the scope of this book.