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Lee Sedol vs. Handol AI

Lee Sedol’s Retirement Match with Korea’s AI Program

Yuan Zhou

Buy the full book at gobooks.com

Yuan Zhou thoroughly analyses the three game match in which Lee Sedol again wins a game against a strong AI go program. Most game diagrams have only one or two moves to aid study.

About the Author

Yuan Zhou (American Go Association 7 dan) was born in Tianjin, China. Tianjin is a major city in the northern part of China, near Beijing. His father taught him to play go at the age of six, and a year later he won the Tanggu District Junior Go Championship. After this auspicious beginning, Zhou began professional go training while he was still seven years old. He was twice invited to represent Tianjin in the All China Prodigy Cup.

In 1989 Zhou immigrated to the USA, becoming a US citizen and joining the American Go Association (AGA). Zhou was the president of the University of Maryland Go Club, from which he earned a BS in Electrical Engineering, and became increasingly involved in AGA events, winning many go tournaments. Zhou was also elected to the AGA board of directors in 2005.

Zhou is one of the top competitors on the American go scene, winning the Eastern US Open, one of the biggest US tournaments in 1992. He also won the New Jersey Open, one of the biggest US tournaments, four times. Twice he has won the Maryland Open, another major tournament that attracts strong players. Zhou has placed in the top ten in the US Open many times, as well as in the North American Ing Masters Cup and the North American Fujitsu Qualifying Tournament. These tournaments involve the strongest North American go players and include pros. In Zhou’s go career, he has defeated pros many times, including four times in even tournament games: Hak Soo Kim 6p in the 1996 Fujitsu, Xuefen Lin 1p in the 2001 Eastern Oza, Huiren Yang 1p in the 2009 North American Ing Masters, and Feng Yun 9p in the 2011 SAMG World Team Go US Team Qualifier. Zhou also won the US Pair Go Championship four times. Zhou represented the USA in international tournaments many times (WAGC, Korea Prime Minister Cup, World Pair Go Championship, etc).

In 2009, Zhou represented USA in the 4th Korea Prime Minister Cup World Go Championship in Jeonju, Korea and finished 5th place.

In addition to his competitive successes, Zhou has become a popular teacher and lecturer, frequently giving lectures and teaching lessons at various go clubs in the Eastern US region. He has also published many go books with Slate & Shell (www.slateandshell.com) and SmartGo Books (gobooks.com). Zhou resides in Germantown, Maryland, USA. His website is at www.zhouyuan.com.

Copyright Page

(c) 2020 Yuan Zhou

All rights reserved. Reproduction in whole or in part is prohibited.

Slate & Shell

www.slateandshell.com

Edited by William Cobb

Conversion to SmartGo Books by William Cobb

Table of Contents

Lee Sedol vs. Handol AI
Lee Sedol’s Retirement Match with Korea’s AI Program

About the Author

Copyright Page

Introduction

Game One

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

Game Two

Game Three

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About SmartGo Books

Introduction

The fact that the famous Lee Sedol 9P of Korea has retired at the age of 36 is no longer surprising in the current world in which professional go is dominated by players in their late teens and twenties. He was at the top of the go world for several years, winning eighteen world championships, and he was the only pro to defeat a version of AlphaGo—in his five game match with that AI. (See my book AlphaGo vs. Lee Sedol: The Match that Changed the World of Go.)

There is an ancient tradition about the retirement of top go players: they have special final retirement matches with an opponent of their own choice. Probably the best known case is that of a game in 1938 between Shusai, the last of the traditional holders of the Honinbo title, and his chosen opponent Kitani Minoru, which was the subject of the famous book The Master of Go by Yasunari Kawabata. Of course, Lee Sedol’s choice of an AI program as his competitor was unprecedented. Since he had managed to win a game against AlphaGo in their match, he was eager to defeat an AI program again.

The acknowledged strength of the AI program Handol (the top Korean AI program) meant that the match would start with Lee Sedol holding a two stone handicap with Black. He had played even in his match with AlphaGo and had great hopes to get back to even against Handol. So winning the first game was a very happy moment for Lee Sedol, although his hope of playing White was dashed by bad luck in the nigiri.

Nevertheless, the match clearly displays Lee Sedol’s amazing ability at contact fighting. The games are excellent studies for go players.

Yuan Zhou, Spring 2020

Game One

In the first game of their three game match, Handol gave Lee Sedol two stones. However, due to the structure of the AI program, Handol received a komi of seven and a half points. So the situation is more like White simply passed on its first move. At this level, of course, this is still a significant advantage for Black. With Black having two stones on the board, everything about the opening changes. Nevertheless, Lee Sedol thought it unlikely that he could win, but he was determined to do his best with his usual fighting style. The basic time limit is two and a half hours each.

Moves 1–3

Naturally, Lee Sedol takes a third corner with Black 2, and Handol makes the two-space high corner enclosure with White 3, which has become popular since AlphaGo introduced it.

Since White starts off a move behind, a normal two stone handicap game strategy for White would probably be to approach one of the corners at A or B with 3, playing faster to catch up. Defending a corner first in a handicap game is interesting. Black’s next move shows Lee Sedol’s style.

Move 4

Lee Sedol is aiming to fight with Handol, since contact fighting is Lee’s greatest strength. He approaches the lower right corner at its most vulnerable point immediately. Normally, we would expect Black to defend one of his corners, which would be big. Lee’s fighting spirit is pretty high.

Move 5

It would definitely be too slow for White to defend in the lower right so instead Handol approaches in the lower left. In effect, fighting has already started.

Move 6

Lee ignores White’s approach move and attacks with Black 6. Black aims to cut White into two pieces. See my book Using AlphaGo’s Enlarged Corner Enclosures.

Moves 7–10

White will save the corner.

Moves 11–12

Naturally, White connects in the corner with 11. Lee decides to play Black 12; this puts more pressure on the corner. He could also have played at A: 12 leaves the connection back to a little thin.

Move 13

Since the pressure on the corner is higher in this case, White defends with 13.

Move 14

Black is able to make a double purpose move with 14, creating a comfortable position at the bottom, pincering White’s lone stone there. Since there is nothing for White to fight with on the bottom now, jumping out would not have much meaning.

Move 15

So Handol simply goes for the corner with 15.

Moves 16–21

A normal joseki follows to Black 20. Until recently, Black would connect at A after White 21. Now, thanks to the AI programs, players are more likely to see the cut at A and the turn at B as miai and play elsewhere. Black could also consider extending at C.

Move 22

So Black pulls out his two stones with 22, aiming for a fight.

Move 23

Since Black didn’t connect, White cuts with 23, obviously considering this the biggest play and in effect making a trade.

Move 24

Black then makes another big move at 24. The key to this opening now will be the fate of the two stones.

In the full book, this game is analyzed to the end.