The world's strongest professional player could not beat a go artificial intelligence (AI) even with a handicap.
World No. 1 Shin Jin-seo, 9-dan, on the 17th lost by resignation as Black to the go AI program KataGo after 245 moves in Game 1 of the best-of-three "Ssen Math·Hankyung Gisinjeon" held at The Korea Economic Broadcasting studio on Cheongpa-ro in Jung-gu.
The match was played with Shin Jin-seo taking Black and a two-stone handicap. Before the start, the AI predicted Shin's win rate at 99% and assessed an advantage of more than 18 points.
Starting from a disadvantage, KataGo unveiled unorthodox moves from the opening. Unlike usual practice games, after placing the first move on the star point, it played a high three-space approach to the upper-right corner as its second move. Hong Min-pyo, the national team head coach providing TV commentary, said it was "a move I've never seen in my life," unable to hide his surprise.
Shin Jin-seo, who had revealed a strategy to avoid fighting and head for territory play, secured profit by solidifying the upper-right corner with a knight's move even against KataGo's unorthodox play. Managing the board calmly, Shin maintained a favorable position through the midgame.
But as more stones accumulated, KataGo's calculation ability began to outpace Shin's. Shin's expected win rate dipped bit by bit, and when move 90 turned out to be a mistake, it plunged into the 80% range.
The decisive moment came at move 102. To capture the central white group, Shin launched a strong move to encircle the opponent's stones. But this proved overreaching, and the balance of the game flipped. When KataGo easily resolved the situation and saved the white group, Shin's expected win rate crashed to the floor.
Shin then played more than 100 additional moves and even continued into a ko fight on the upper side, but could not close the territory gap and finally resigned after 245 moves.
In this event, a resignation can be declared only after more than two-thirds of the time limit has elapsed and either a large group is captured or the territory gap exceeds 30 points. Shin was given a five-hour main time with a single 30-second byoyomi, while KataGo had no time limit and played each move within 20 seconds.
Shin Jin-seo receives 50 million won per game, totaling 150 million won, and is paid an additional 50 million won for each win. If he records two or more victories, he also receives a Genesis G90 as a prize. KataGo's moves were relayed by Lee Dan-bi, 1-dan, of the Korea Baduk Association.