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Shin Jin-seo 9-dan, the world's top-ranked Go player, takes on KataGo, a state-of-the-art Go AI, in a three-game series at the SSEN Math & Hankyung Kishin Match. Shin defeated KataGo in the match held at the Korea Economy TV studio in Jung-gu, Seoul, on July 21. / Courtesy of Yonhap News

Shin Jin-seo 9-dan demonstrated the power of human intellect by defeating KataGo, a state-of-the-art Go AI.

On July 21, at the Korea Economy TV studio in Jung-gu, Seoul, Shin defeated KataGo by 11.5 points in 221 moves in the final Game 3 of the SSEN Math & Hankyung Kishin Match, securing the overall victory with a 2-1 record.

Despite a shaky start following an unexpected defeat in Game 1, Shin staged a dramatic comeback by winning Games 2 and 3 consecutively. The victory carried immense significance as a human professional's successful fightback against cutting-edge AI.

Game 3 was played as a two-stone handicap match. Shin began the game with an initial 18.5-point advantage and an expected win rate of 99%.

However, KataGo deviated from its previous strategies, opening with a komoku (komoku-point) in the upper-left corner. Caught off guard, Shin deliberated for roughly two minutes before responding carefully with a komoku in the lower-right corner.

When KataGo solidified the upper-left with a two-space enclosure, Shin formed a stable knight's move structure in the lower-left corner. The match proceeded into the mid-game without major tactical clashes as both sides focused on territory, allowing Shin to carry out his pre-planned strategy smoothly.

Prior to the series, Shin stated that he intended to "avoid fighting as much as possible and settle the match through territory," a plan he executed faithfully in the final game.

Around Move 80, while attacking White's stones, Shin constructed a massive Black territory stretching from the top side to the center. As this influence materialized into solid territory, he seized a decisive lead, successfully blocking the AI's pursuit through stable board management rather than complex tactical fighting.

Even after securing a clear advantage, Shin maintained concentration until the end. Having seen his 99% win rate evaporate by Move 70 in Game 1 and Move 160 in Game 2, he protected his lead flawlessly throughout the third game.

After approximately 3 hours and 20 minutes of play, Shin secured victory by a wide margin of 11.5 points in 221 moves.

Pre-match expectations had been lean. Even with a two-stone handicap, many in the Go community felt that securing even a single win against a top-tier AI's computing power would be a meaningful achievement.

Nevertheless, Shin demonstrated the enduring potential of human Go in the AI era by triumphing over KataGo's formidable reading abilities.

During the match, Shin was allotted 5 hours of main time with one 30-second byo-yomi, while KataGo operated without a overall main time limit, placing each move within 20 seconds.

With a final score of 2 wins and 1 loss, Shin receives a total prize of 250 million won including match fees, along with a Genesis G90 as a victory prize.

The KataGo system used in this match was hosted by online Go platform Tygem using a dedicated rig equipped with four parallel RTX 3090 graphics cards. KataGo's moves were physically executed on the board by Lee Dan-bi 1-dan of the Korea Baduk Association.

                                                                                                         Cheon Hyun-bin