Review: Mastering Basic Corner Shapes - Step-by-step


  • Title: Mastering Basic Corner Shapes - Step-by-step
  • Author: Young Sun Yoon
  • Publisher: Korea Baduk Association et al
  • Edition: 2022-12-25
  • Language: English
  • Price: EUR 0 (plus any commission or postage)
  • Contents: life and death
  • ISBN: none
  • Printing: good
  • Layout: good
  • Editing: intermediate to weak
  • Pages: 270
  • Size: 153mm x 224mm
  • Diagrams per Page on Average: 2
  • Method of Teaching: selected examples
  • Read when EGF: 7k - 1k
  • Subjective Rank Improvement: o
  • Subjective Topic Coverage: -
  • Subjective Aims’ Achievement: +


The book Mastering Basic Corner Shapes - Step-by-step contains life and death problems, answer diagrams and accompanying text. Besides short introduction, diagram index and appendix, the main part comprises 50 chapters on 229 pages. 36 chapters contain the problems while 14 chapters refer to their joseki origins. In the former, every chapter has 4 problems and a brief summary. Subtracting one duplicate, there are 143 problems. Within each chapter, the difficulty increases from the first to the fourth problem typically with a position a few moves earlier. Apart from the appendix, there is no structured theory.


The book claims to present basic corner shapes and this is mostly correct. Of course, no single book can cover all shapes. The curios omission, however, is the most frequent basic corner shape resulting from the 3-3 under 4-4 invasion. Otherwise, the author has selected the shapes well: they occur rather frequently and offer a decent variety of techniques. The selection differs from All About Life and Death and more basic life and death books so makes more shapes accessible to the English literature.


For the four problems of a chapter, there are altogether about half a dozen to a dozen answer diagrams with short commenting texts, which contains hardly any further variations. The diagrams show solutions, variations, failures, or sometimes additional analysis.

The author speaks of the most relevant sequences in the diagrams. Some of them are relevant indeed but the reader must not fall under the illusion of sufficient diagrams. The greatest weakness of the book is the missing variations. The reader must read about two or three times as many relevant variations as shown. As a related aspect, the author mentions visualisation, memorisation and neuroscience in the introduction and appendix but fails to explain tactical reading and its decision-making, which would also consider the missing variations. A reader knowing tactical reading and reading all relevant variations can, however, profit more from the book by overcoming the author’s or publisher’s desire of pretending easy teaching and prominent layout.


Some of the problems might also be suitable for 10k - 8k players but such readers face the difficulties of the missing variations and presumed knowledge, although the appendix, which introduces bent-4, 10000-year-ko and approach ko, might mitigate this a bit if read in between. A few problems have some variations of intermediate difficulty suitable for low dans but a dan would not read the whole book just for them or a basic type of ko previously neglected in other texts. Hence, the core readership is 7k - 1k. A dedicated low dan should not condemn the book though, as it is a reminder of what he should know but probably partially might be missing. A reader can first solve the problems and then consult the book again for memorisation.


Although the book must have undergone some proofreading, there are many minor mistakes of language or sometimes contents but they do not obstruct reading significantly. An accompanying leaf only lists a few of them. There are occasional relevant mistakes of contents, such as swapped diagrams, a suboptimal solution disregarding the endgame, a few terms on ko types and counting versus scoring used wrongly, and consequences of shapes in the appendix for rules application. A reader of a free book can easily forgive such but should not blindly trust everything.


The author has been enabled to create the book so that it can be free. However, it might not be easily available because reasonable postage cannot be offered everywhere these days. Therefore, you might have to await distribution at some large tournaments or possibly pay some commission to a retailer.


Mastering Basic Corner Shapes - Step-by-step is a welcome addition to the English literature offering suitable practice for problem solving but should show more relevant variations, include the most frequent class of shapes and receive better proofreading.


This book is free? Where can it be obtained? I could not find it available with a few minutes of quick googling.

What do these symbols mean?

neutral, negative, positive?

The author and her helpers are still figuring out how to distribute the book so it may need more time until you can actually get it. However, maybe you can ask the author directly? She might prefer German or Korean; I am not sure how well she understands English.

For the symbols, please see here.


Her English is good - after all, she has a YouTube channel in English, where she also presents parts of the book, by the way.

Thanks for the review!


John Fairbairn posted another review here: Review: Mastering Basic Corner Shapes - Step-by-step • Life In 19x19
I also received a copy of the book. The first chapters are:

  • L-group: White tries to live with an L-group, Black to kill.
  • L+1 group: Black to kill.
  • L+1 group + hane (I): Black to kill.
  • L+1 group + hane (I): Black didn’t make the correct killing move, White to punish.
  • L+1 group + the other hane
  • L+1 group + the other hane: punishing mistakes
  • L+1 group + two hanes
  • Origin of the L-group

Each chapter consists of four problems, generally of increasing difficulty; problem 4 may use ideas of the easier problems 1-3. For each problem, the solution proposes several diagrams which are commented in detail. I agree with Robert Jasiek that not all relevant variations are shown, however I don’t think it’s a weakness of the book. The purpose of the book is to train the reader in life and death, so the reader is expected to read actively and check that the variations are indeed correct. In principle, enough branches are shown to make the reader aware he missed an important variation, and the last verification steps should be an easy exercise.

Already from the first chapters, I felt that my previous knowledge of the L-group was incomplete. Of course I already knew that the L-group was dead and knew how to kill or to live with an L+1-group, however I was far from aware of all variations.

The book continues with other classic shapes that may arise from common sequences and explores a variety of techniques. I haven’t read them yet but I’m pretty sure I’ll learn something in each chapter. So it’s safe to say that the book will be profitable for readers in the range EGF 9k-1d. I hope the book will be more widely available in the coming months.



Thank you for reporting about your first steps in Young Sun Yoon’s new book which is currently not commercially available and has only been distributed for free. The limited edition of 300 volumes is almost used up but a certain number will be made available at the EGC 2023 in Leipzig. Copies were distributed in go events in India by Yeonwoo Cho 2p, she runs AwesomeBaduk with Young Sun Yoon. Also, other Korean professionals distributed copies abroad. The book is now studied by players in the US, Iceland, Benelux, France, Germany, Romania, Ukraine, Korea, Japan, Thailand, the United Kingdom, and probably more countries. As co-author of this book, I should not express myself as enthusiastically as I did on this forum about John Power’s recently released book on proverbs but am confident to say that our book is very solid.
Young Sun Yoon’s approach to deconstructing an otherwise difficult problem into 2-3 easier ones is very helpful for the learning process. Laurent Heiser, 6 dan from Luxembourg (multiple participations at the World Amateur Championship, 4th place twice just behind the top Asian players, six times among the prize-winning top eight) assisted as a consultant all along the production of the book. With his huge library of Chinese, Japanese, and Korean books Laurent is not only a practical but also a theoretical expert of our game. Also, Rob van Zeijst, 7 dan from the Netherlands and author of many go books gave essential assistance.
In the introduction we discuss also the importance of visualization in the reading process, compared to chess, this has been totally neglected in go, we suggest also visualization exercises and discuss the neuroscience of learning.

The next plan is to make the book available as a SmartGo book, real books with translations into German and French are also considered. In her announcement on Yoon’s Baduk Café, Young Sun Yoon “promised” that reading the book would make you 5 dan, of course, this wasn’t meant to be taken literally. For those who can’t wait to get a copy: Over 30% of the book is already available in Yoon’s Baduk Café on Youtube, search for the step-by-step videos as well as the 2 bent four videos. The author plans videos of all the chapters in her book and started to produce these new videos already. In the book, the problems are treated in greater detail. While waiting, a good preparation for the book is also (re)-studying Life and Death by James Davies as well as the first volume of Cho Chikun’s Dictionary of Life and Death.

If you are interested to get a remaining copy, please send me an email, mentioning your strength and country of origin as we want to give feedback to KIBA. If there are more people interested than we have books available, a lottery is considered: []

Paul Schmit


Hi Paul,
I would be interested in getting a copy of this book. I am from France, 10 k in FFG (french go federation) and participate in the Awesome Baduk’s 1-dan-challenge.
Thanks in advance for your reply.
Kind regards
Jean-Pierre Ladet (