© 2024 by Tony Yang and Han Han

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The Theory of Go

by
Tony Yang and Han Han

From years of professional experience competing and teaching, this book presents seven essential lessons on Go theory that every player should know, alongside carefully chosen examples from professional games. From this book, readers will uncover the key principles that shape strategic thinking in Go and master how to choose their very next move.

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About the Authors

Tony Yang, born on October 20, 2008, is an AGA-rated 7 dan, who is currently a high school student in Southern California. He was the back-to-back champion of the 2022 & 2023 U.S. Go Congress Open Division, and took 3rd place in the 38th World Youth Go Championship. In 2024, he launched ScribeGo, an innovative iOS app that allows users to study and replay professional Go matches with ease. Moreover, Yang has had experience as a teacher, having taught Go at his local Chinese school and the San Diego Go Club.

Han Han (韩晗), born on July 11, 1989, is a Chinese professional 5P who has had a distinguished career in both competition and teaching. He became a professional in 2003 and was promoted to 5P in 2009. In 2012, Han qualified for top 32 of the 1st Bailing Cup. In 2004, he was a member of Team Xinxing, the runner-up in the China Weiqi League. Moreover, Han took 1st place in the 2022 & 2023 U.S. Go Congress Masters Division. He currently teaches Go with students from both the U.S. and China.

Copyright Page

© 2024 Tony Yang & Han Han

All rights reserved.

No part of this book may be reproduced in any form without permission from the authors, except for the use of brief quotations in a book review and certain other noncommercial uses permitted by copyright law.

ISBN of print edition: 9798339996972
Amazon: https://a.co/d/bBS4asC

For permissions, inquiries, or other information, contact: tony08.morgan@gmail.com

Contents

About the Authors

Copyright Page

Contents

PREFACE

LESSON 1: THE ART OF THINKING

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

LESSON 2: STRONG AND WEAK STONES

LESSON 3: JUDGING STRENGTH

LESSON 4: GRASPING DIRECTION

LESSON 5: READING

LESSON 6: THE ESSENCE OF SHAPE

LESSON 7: JUDGEMENT

Buy This Book

About SmartGo Books

Theory will only take you so far.

But this is Go, not life…

PREFACE

In 2016, the world of Go was shaken when AlphaGo, an artificial intelligence program, achieved the unimaginable—defeating the legendary former world champion Lee Sedol, showing AI’s towering strength over humans. Nowadays, AI helps many strong players train and study Go. Since the rise of artificial intelligence in Go, AI has pointed out many flaws within traditional openings and josekis, debunking some inherent principles of Go theory. This begs the question: Do we still need theory to become a stronger player? Some players may argue that although AI’s powerful calculations lead to moves beyond the understanding of many, simply imitating AI can still make them better Go players. In a sense, AI has shaped the idea that Go is not necessarily a game of underlying principles and has made theory seem less relevant.

Indeed, some of the traditional Go theories, especially in the opening, are outdated. From the perspective of professional and strong amateur players, it makes sense to change their cognitive approach on Go, as mimicking the play-style of AI and sharpening their computational skills are a high priority. However, the majority of Go players and enthusiasts who are not as strong as these professionals will find it much harder to control and integrate themselves into certain situations if they blindly follow AI’s moves. This is due to the gap in theory and computational abilities.

Certainly, AI has had a large impact on Go theory, altering different ways of thinking within the game. However, there are still core principles that remain unchanged. For example, the Go proverb “Corner is gold, side is silver, center is grass” is consistent with AI. AI agrees with the value of corners, suggesting corner enclosures over side extensions after the corners are taken. For Go players at an intermediate level, theory can help you think more rationally and make more effective decisions in games. Now, with the capabilities of AI, its assistance can be used to help analyze and confirm theory. Thus, Go theory nowadays will be closer to the truth than it ever has been.

Keep in mind, it’s difficult to find examples and scenarios that are both accurate according to AI and easy to understand for readers. Although moves pointed out by AI are usually highly accurate, oftentimes they are not easy to understand. With that in mind, this book will select examples and scenarios played by professional players. These moves may not always be AI’s first choice, but are still considered good moves by AI. They are somewhat difficult moves, but relatively easier to understand.

In short, this book is largely aimed towards Go players at an intermediate level (~low kyu to 5 dan) to help you improve your understanding of Go theory, and thus improve your Go strength. Go theory can be thought of as the philosophy of the ancient game. It’s the fundamental understandings and principles that drive almost every move. This book focuses on theory but differs from many traditional theory books. Such books are usually divided according to the stages of the game: the opening, middle game, and endgame. They often give you stereotypes that the opening is about breadth, the middle game is about life and death, and the endgame is about value. Nowadays, boundaries between different stages of the game are becoming increasingly blurred and interconnected. For example, in many games, fighting occurs in the opening and can even spread throughout the entire game. And in some games, there can be barely any endgame moves at all. In this sense, traditional theory can easily become confusing. Therefore, we adopt a new approach in this book, simplifying scenarios into two situations: the presence of weak stones and the absence of weak stones. Additionally, we focus deeply on the thinking and analytical level, to answer the question: When playing Go, how should we think about each move?

We believe that a clear and improved method of thinking will be especially helpful to players around the dan level. Throughout this book, we emphasize practicality, as we aim to help construct a method of thinking that’s not only effective but also practical. Of course, the theory and ideas conveyed in this book are derived and limited by the authors’ personal experience and Go skills. It’s important to note that as the game of Go is inevitably complex, there is no “perfect” method to encompass such a game. With that, we hope this book and its content can help nudge you in the right direction as well as guide your gameplay.

LESSON 1: THE ART OF THINKING

In Go, how you think lays a foundation for every move you play. This lesson will dive into the minds of professional Go players and show you how they think and make decisions for each move. The first step to thinking like a pro is to think before making each move. Seriously. This might seem obvious, however after 15 years of teaching Go, teacher Han realized that at least half the students he’s taught struggle with this. This bad habit is a result of lazy thinking. You might be wondering: then how come pros make very quick moves in certain areas? But that’s because they think very quickly, not because they don’t think at all. There are certain areas in a game that only require straightforward calculations which may come quickly for many players. However, in vast and vague areas, even pros need to take their time and ponder deeply. So, how should we think?

From our experience in playing and teaching, we have crafted a four-step method to thinking, which is also similar to how most pros think. As for how to use them, we will explain in detail in the following lessons. In our opinion, the method of thinking always revolves around the following four steps, and the essence remains unchanged.

LOCATION

Due to the vastness of the Go board, we can’t calculate everything. So, we must narrow the scope of thinking by focusing on the right location.

Diagram 1: Transatlantic Professional Go League
(B+) Kevin Yang (1P) vs (W) Pavol Lisy (2P)

In Diagram 1, the situation is quite chaotic. Many groups on the board aren’t alive. Where should Black play? We suggest you take some time to think about it. This is a typical location and positioning problem.

Remember: Only by accurately evaluating the location can we proceed with further thinking.

DIRECTION

The right location helps us determine the area where we should play. Next, we must correctly determine the direction of the move. When teaching, I often joke with students about not kicking the ball to the opponent’s goal. This is indeed the case. Playing in the wrong direction is a common mistake made by many players. If your direction is off, no matter how clever your ideas are or how accurate your calculations are, it’s often useless. It’s like kicking a perfect arc, but the ball flies into your own goal. That would be pretty disappointing.

You can imagine the direction as a line. Once this line is determined, you can think about your choice of points along it. With this, does the scope of thinking narrow down a bit?

Diagram 1.1
Direction Diagram (continued from Diagram 1)

After a bit of thinking, we conclude that Black should play somewhere outside and near the center of the board. This is because most of the weak stones on the board are concentrated here. With that, among the three directions in Diagram 1.1, how should Black choose?

Remember: It doesn’t matter how much you calculate your next move if the position and direction are wrong. Before they are correctly determined, your calculations will be meaningless.

READING

As you narrow your focus from the entire board to a specific area and then to a single line, your thoughts will become clearer. Now it’s time to read (otherwise known as calculating). When reading you should conduct breadth and depth reading. Breadth reading involves picking several moves that seem good and evaluating each one. Depth reading, on the other hand, is about exploring the sequences of one particular move more in-depth.

Diagram 1.2 Selection of moves

After some consideration, attacking downwards seems like a great direction for Black. Attacking downwards not only helps the middle group move outwards, but it also applies pressure on White’s right group, forcing White to move down towards more Black stones. Looking at Diagram 1.2, if you think that attacking downwards is the correct direction for Black, then moves A and B seem like potential candidates to achieve this. Next, we need to calculate the possible variations for these moves.

Diagram 1.3

In Diagram 1.3, Black 1 jumps out to apply pressure to the White group on the right, White 2 moves out, Black 3 extends safely, White 4 extends to retreat, Black 5 secures the bottom, and White 6 and Black 7 each move out.

Diagram 1.4

In Diagram 1.4, Black 1’s two-space jump is more aggressive than Variation 1, but it is also riskier. White 2 and 4 threaten Black’s connection weakness, so Black can only atari at 5. White atari’s at 6 and then enters the bottom at 8, making Black’s situation quite tricky.

Diagram 1.5

Diagram 1.5

Going more in-depth for a specific candidate (continuing from Diagram 1.4), additional reading follows it. In Diagram 1.5 above, when White plays 4, Black might be tempted to extend at 5. However, White’s push at 6 is dangerous for Black. White then follows with a series of sente moves, ending with White cutting at 14. In this variation, Black lacks the necessary liberties and will be captured.

Diagram 1.6

Taking a look at Diagram 1.6, Black’s 1 is too much. After White pushes through at 2, if Black follows through with the aggression with 5, White’s 6 and the rest will severely threaten Black’s upper group. Black is not in a favorable position and will be captured, similar to Diagram 1.5.

Reading in a breadth manner can help you avoid the consequences of blindly making a move after only reading that move. If you are not confident that your initial intuition is correct, be sure to lay a few more paths for yourself. However, it’s not ideal to consider too many moves at once as it can easily become confusing.

JUDGEMENT

At this point, you have read the results for several possible moves and the readings are overall correct. Often, the pros and cons of these results are obvious at a glance. For example, in Variation 3, Black loses the capturing race. Black’s 1 was too aggressive and was later punished by White.

When the pros and cons are obvious, we can make our decision pretty quickly, and there is no need for a concentrated judgment. Judgment, which is the final step we emphasize, is necessary when different variations have ambiguous outcomes. In general, many complex scenarios sometimes have this characteristic.

So, how should we make judgments when the outcomes of these variations are not clearly comparable? We will elaborate further on this in Lesson 7. For now, our example scenario has fairly straightforward outcomes. Thus, after comparing the variations, we will make a decision on our move.

Considering all three variations in our example, our final choice should be the small jump for Black in Variation 1. Did you get the same answer?

To summarize, the four-step thinking method can help us make clearer decisions about each move:

1. Location: Determine the area of ​​the move

2. Direction: Grasp the direction of the move

3. Reading: Read the outcomes of each candidate

4. Judgment: Compare the outcomes and make your decision

Congratulations! You have now learned how to systematically think about each move. In general, for vague, entire-board scenarios, you should consider all four steps of thinking. For more local scenarios, sometimes one or two steps are sufficient. Overall, we suggest that you familiarize yourself with the four-step thinking method and apply it to the decision-making of each move.