History
Go is the oldest board game, but 9 × 9 Go is not common before 1970. Go on 9 × 9 board was played and first recorded in 1968, when Naoki Miyamoto 8p (Black) defeated Go Seigen 9p in the first game of the legendary 2-game komi deciding match in Japan. Go on 9 × 9 board was first considered comparable to Chess in complexity by Albert L. Zobrist (1969), when he was a Ph.D. student at the University of Wisconsin. He was the first to write Go playing program, as part of his Ph.D. thesis, and his colleagues Mr. George Cowan was the first human to defeat and be defeated by Go bot (+2-2=0), in the four-game match, and Prof. Paul Purdom was the first to comment the game of Go played by human against bot.
Go on 9 × 9 board was not common in Great Britain before 1970 as well. Francis Roads noted in 1971 that he has experienced playing Go on the 13 × 13 and 10 × 10 boards. The International Computer Games Association (ICCA) was just founded in 1977. Then, David Fortland started playing Go seriously in 1979. In 1981, he decided to write a go playing program, when he was 15 Kyu. His program became known as Many Face of Go.
In 1984, the first Computer Go Tournament in the US was organized by Peter Langston as part of the 1984 Usenix conference. Acornsoft Computer Go Tournament was also held in London by the British Go Association that year. A year later, Francis Roads wrote the first article on 9 × 9 Go published in British Go Journal, No. 66 (November, 1985).
The game of 9 × 9 Go became wildely known in Japan when a 9 × 9 Go match was broadcast on Yomiuri TV in Osaka, every Sunday morning from April 1987 to June 2002. Initially, the most common board sizes were still 8 × 8, 13 × 13, 17 × 17, apart from 19 × 19. In 1988, Karl Baker used the 8 × 8 Go as illustrations in his book, The Way to Go, while Cho Chikun 9p encouraged the use of 9 × 9 Go for learning the basic of Go.
Globally, 9 × 9 Go has gained in popularity since the late 1990s, after Windows 95 was released in 1995 and David Fortland published a 9 × 9 free version of Many Face of Go, called Igowin for Windows, which is the strongest computer 9 × 9 Go freeware at that time, although the Computer Go Olympiad, organized by ICCA, had been started since 1989 for 9 × 9 boards, with the initial tournaments held in London and won by Dragon Go.
Michael Reiss's GO++ became the strongest computer Go programs in 1999, when winning the ING Cup that year by beating all its opponents, including Handtalk, a long time world champion among go programs from 1993 to 1997. However, Fortland's full strength Go program, Many Faces of Go, was the first commercial Go program. This Go engine has been employed in the iPad app called Igowin HD, with the maximum strength of 1 Kyu, or 1 Dan Go Quest. If a player can defeat it 10 games in a row, Igowin HD will promote him or her to be 8-Dan.
The game of 9 × 9 Go has become even more popular when people could play Go online against human Go players around the world on Yahoo! Games, from 1998 - 2016, where there were 9 × 9 Go Rooms for beginners and advanced Go players worldwide.
In 2008, MoGo defeated Catalin Taranu 5p, and is the first computer Go program to win as Black against a pro (Gelly and Silver, 2008). Then, in 2009, MogoTW defeated Chun-Hsun Chou 9p, who won the LG Cup 2007. So, MoGoTW is the first program to win as Black againts a top pro, according to Billouet et al. (2009). In the same year, In the same year, Enzenbeger and Muller (2009)'s Fuego was the first computer program that won an official game of 9 × 9 Go against a 9-Dan professional player, Zhou Junxun, at the Fuzz IEEE 2009 conference. The game record is given at the conference webpage.
Since 2010, a popular 9 × 9 Go server among oriental 9 × 9 Go players has become Go Quest. Then, Yahoo! Games was closed down on March 31, 2014. More than 30,000 users were 9 × 9 players on Go Quest, with around 25,000 Kyu players (Elo < 1700). Many of them had played more than 10,000 games and cannot yet achieve 1 Dan, although the minimal rating requirement for being 1 Dan player had been relaxed from 1750 to 1700. Superhuman players, especially those who topped the chart and defeated :AyaXBot with ease, were inactivated by the admin. Most of them were 9 Dan players. That is in part why no 9 Dan players appear on the ranking chart of Go Quest today.
In 2013, David Silver led DeepMind's AlphaGo project, developing 19 × 19 Go program called AlphaGo, subsequently promoted to honorary 9 Dan Professional after AlphaGo defeated Lee Sedol 9p (4 : 1), and argurably became the world strongest Go program. Then, the program was trained using reinforcement learning algorithms, and achieved superhuman performance. The strongest form of AlphaGo was AlphaGo Zero, which defeated AlphaGo Master 9p Chinese (89 : 11) which had defeated the world number one ranked player Ke Jie 9p in 2017 (3 : 0). AlphaGo Zero also defeated AlphaGo Lee 9p Korean (100 : 0) which had defeated Lee Sedol 9p in 2016 (4 : 1), who referred to AlphaGo as being an entity that cannot be defeated. The source code of AlphaGo is not opened because it depends so much on other Google technology that the source code to just AlphaGo would be completely useless, according to Google Engineer Andrew McGregor. Nevertheless, scientific papers on AlphaGo have let other scientists to develop other superhuman Go programs that are open source Go bots, namely ELF OpenGo, SAI 9 × 9, Leela Zero, and KataGo.
It was in May 2019 that a superhuman 9 × 9 Go AI first existed, when SAI defeated Hayashi Kozo 6p and Oh Chimin 7D with komi being 6, on 9 × 9 board, considered an achievement that classifies SAI as superhuman (Morandin et al., 2019).
At the time of this writing (2023), there are many superhuman 9 x 9 Go AIs. A Master of Go 9p+ (v6.0.1) defeated its old version in 2023 (2 : 0) which topped the chart of Go Quest in 2019 by defeating all 30 Kyu to 9 Dan human opponents on Go Quest (100 : 0), including a Japanese 6 Dan professional Go player (1 : 0). In 2019, KataGo defeated ELF OpenGo (3 : 0) that beat the four top-30 professional players (20 : 0) on 19 × 19 board, when KataGo's Elo rating was below 500. A Master of Go exploits KataGo engine (v1.12.4) and the brand-new 18 block NBT weight (ca. 13,557 Elo) that replaces the 40 block weight (ca. 13,468 Elo), verified and promoted to 9p+ by WGA, and used for analyzing the 9 × 9 Go games of KataTest 9 Dan, the number one ranked player on Go Quest, with the best game results in Go Quest history (92 wins, 0 loss, 1 draw). The NBT weight was the strongest confidently-rated network in March 2023, which is copyrighted by David J. Wu ("Lightvector"). In this project, A Master of Go was used with kind permission from Mr. Yuji Ichikawa.