Ke Jie

2008–15: Early Career and Bailing Cup Breakthrough

Ke Jie started to learn how to play go in 2003 when he was 5 years old and won his first national championship in 2007. He became a professional go player in 2008 when he was 10 years old and was promoted to 9 dan in 2015.^[6] In January 2015, Ke won his first world title when he won the 2nd Bailing Cup, defeating Qiu Jun 3-2 in the finals.^[7]

2015–16: Two International Titles and Chinese No.1

In December 2015, he defeated Shi Yue in the 20th Samsung Cup finals to win another world title.^[8]

In January 2016, Ke won the 2nd Mlily Cup, defeating world renowned go player Lee Sedol in the fifth round.^[9] According to South Korean 9 dan professionals commenting on the final game, the result hinged on a half-point ko and the peculiarities of Chinese scoring rules; however, others have pointed out that this argument is misleading as differences in komi between the Chinese and Japanese scoring systems would have made up the extra point, leading to the same result.^[10][11]

On 11 February 2016, he defeated Lee once more in the finals of the 2016 HeSui Cup.^[12] On 5 March 2016, Ke defeated Lee yet again in the finals of the 2016 Nongshim Cup to win the tournament for the Chinese squad, making it China's third consecutive win of the tournament.^[13]

Ke became highest ranked player in the official Chinese Weiqi Association ranking in September 2015.^[14][15]

2016–17: Two International Titles

In August 2016, at the 3rd Bailing Cup, Ke defeated Xu Jiayang to advance to the best-of-three semifinal match where he faced Won Seong-jin. In the first game, Won defeated Ke with a comeback victory after Ke had made crucial mistakes when analyzing territory turnover; however, he was able to recover in the second game by playing a very close endgame in which he maintained a territorial lead. In the decisive third game, he continued to make advantageous moves during the middle-game and maintained a comfortable territorial lead. Ke was able to forced a successful ko fight at the top of Won's territory, resulting in the Won's resignation due to a lack of ko threats. Ke then faced Chen Yaoye in the final best-of-five match, which was the third straight Bailing Cup finals to have been contested between Chinese players. The first two games were both won by Chen. In the first game, Chen displayed his tenacity in chasing and eventually leading in territory with very few opportunities for Ke to win in the endgame. The second game was similar to the first, but during the middle game, Ke deviated and began to chase and attack Chen's dragon, forcing Chen to maneuver around the middle of Ke's territory; however, Ke's made a mistake on the 105th move that allowed Chen to retaliate and take the initiative, causing the match to eventually end on move 178.

From 31 October 2016 to 2 November 2016, Ke played against rival Lee Sedol once more during the semifinals of the 21st Samsung Cup.^[16] In the first game of the best-of-three match, Ke was reported to have won a very complete game in which Lee had very opportunities in the endgame; however, going into the second game with no breaks, Ke was not able to maintain his advantage with the white stones and Lee produced one of his trademark comeback victories. The game began very evenly until Ke acquired positional advantage, and a huge lead in territory, but Ke made several mistakes when fighting Lee's dragon in the center of the board. Lee responded accurately and reversed the game, saving his stones and gaining a lead in territory. Lee closed out the second game with a stunning comeback victory. With black winning both games by resignation, the third game had both players coin-toss for the choice of stones. Ke had the white stones in the third game and was able to secure all four corners to gain a territorial lead from the beginning. The remainder of the game displayed his ability to invade and scrape away Lee's territorial potential. As Lee began to find it difficult to gain any territorial advantage, he pressed on the weaknesses of white's territory hoping to reverse the game, but Ke responded accurately and did not allow any opportunities for Lee. Lee resigned the final game, and Ke advanced to the finals of the Samsung Cup for the second year straight. From 6 December 2016 to 8 December 2016, Ke played the finals against compatriot Tuo Jiaxi. After losing the first game with black, Ke won the second game with white to even the match and then won the deciding game with black to successfully defend his Samsung Cup title.^[17][18]

Ke reached the finals of 1st ENN Cup, defeating Ahn Kuk-hyun, Tang Weixing, Ida Atsushi, Lian Xiao and Li Zhe, from November 2016 to May 2017.^[19] Ke won the title by defeating Peng Liyao 3-2 in the finals in December 2017.^[20]

Matches against AlphaGo

On 4 June 2016, at a news conference during the 37th World Amateur Go Championship, Yang Jun'an, the party chief of the Zhongguo Qiyuan and executive of the International Go Federation, revealed that the Google program AlphaGo would possibly have a match against Ke in the future.^[21] However, Google DeepMind CEO Demis Hassabis responded that it had not yet been decided what to do next with AlphaGo.^[22]

In early January 2017, Ke Jie played three unofficial online games against "Master", an updated version of AlphaGo, losing all three. Ke stated he still had "one last move" to defeat AlphaGo.^[23] Regarding AlphaGo, Ke Jie stated that "One can only learn from its strategic philosophy and not only tactics."^[24]

A three-game match was played by Ke Jie against AlphaGo at the Future of Go Summit in Wuzhen from 23 to 27 May 2017. Google DeepMind offered 1.5 million dollars winner prizes for this match while the losing side took 300,000 dollars for participating in the three games.^[25][26][27] AlphaGo beat Ke Jie in the first game by half a point on 23 May 2017. The official scoring for the first match was 184 out of the 361 possible points in favor of Ke Jie, but the Chinese Go rule requires a Black victory of at least 4 over the 180.5 (i.e. 184.5 is the minimum for a Black victory). Ke Jie resigned in the second game after 156 moves and the third game after 209 moves.