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Shōgi showdown for supercomputer

by Tomoko Otake

Staff Writer

Eiki Ito, 49, started programming a shōgi (Japanese chess) computer in 1998, because back then, he says, his job with an IT firm wasn’t keeping him busy enough. Thirteen years later, his pet machine boasts a computing ability of 4 million moves per second. And it may well soon beat one of the strongest shōgi players Japan has ever produced.

Come Jan. 14 next year, Ito, or rather his computer, named Bonkras, will fight head-on with Kunio Yonenaga, a retired professional shōgi master who heads the mighty Japan Shōgi Association (JSA). If the computer — whose name was taken from a Japanese manga character and is a spin on the word bonkura, meaning “dim-witted” — wins the match, it would signal the arrival of a new era in the 400-odd-year history of shōgi, a two-player board game with an estimated 12 million fans around the country.

While computer chess programs have long since proved their supremacy over humans — with the IBM’s Deep Blue supercomputer defeating the then-grandmaster Garry Kasparov in 1997 — shōgi’s professional players have so far avoided the embarrassment. Experts say shōgi is a more complex game than chess and is therefore harder for computers to learn, because in shōgi, players can re-use opponents’ pieces as their own after taking them. But there is another aspect to it.

The JSA, while long supporting and sponsoring the development of computer shōgi games, has tried hard to keep its professional players from falling into the trap that chess players have. In 2005, as Yonenaga realized that the threat of shōgi computers beating humans was imminent, he banned the association’s professionals from playing with computers in public unless “organizers pay a sponsorship fee of at least ¥100 million per game” — thus limiting the pros’ exposure.

“If a professional shōgi player wins a match against a computer, it’s no news. But when a pro loses, it turns into a big deal,” Yonenaga said in an interview published in the January 2011 issue of the monthly magazine Chuo Koron, explaining his 2005 decision.

So far, the association has approved only two man-versus-computer matches since 2005, and results have been mixed. In a 2007 match, Akira Watanabe, a title-holding shōgi player, kept the JSA’s reputation intact by beating Bonanza, a program developed by physical chemist Kunihito Hoki. Bonanza, which incorporated some of chess computers’ features, had won the World Computer Shōgi Championship the year before.

But three years later, when Ichiyo Shimizu, a female shōgi master picked by the shōgi association, took up the challenge, she lost to Akara 2010, a mighty program developed by the Information Processing Society of Japan.

This time, Ito’s Bonkras has been picked, following its victory at the 21st World Computer Shōgi Championship, organized by the Tokyo-based Computer Shōgi Association and held in May. And the 68-year-old Yonenaga — still one of the biggest names in shōgi despite having retired from the game eight years ago — has named himself the contender for the match.

Interestingly, it is not just the computing speed that determines a shōgi program’s strength, says Ito, who works at Fujitsu Semiconductor, a 100-percent-owned subsidiary of the IT giant Fujitsu. (While requiring IT knowledge, Ito’s current job is not related to computer programming.)

Bonkras has three PCs networked together, which respectively have simulating capacities of 1.7 million, 1.4 million and 1.2 million moves per second. In the world championship in May, which Ito entered for the seventh time, Bonkras beat a rival software running on more than 200 PCs.

So what is the key to Bonkras’ success?

“When you connect computers, it’s easy to just to connect them, but it’s difficult to make them work efficiently together,” Ito said in a recent interview with The Japan Times. “For example, when you divide tasks among three computers, there is a chance that one machine might be working at 100 percent capacity, while the other two might be working at a combined 5 percent, so altogether they’re working at only 105 percent capacity (against the total capacity of 300 percent). The key is to raise the computers’ efficiency to, say, 100, 70 and 80 percent, altogether achieving a combined ability of 250 percent.”

Ito’s program uses a search algorithm called “alpha-beta pruning,” through which it picks only the good moves out of all simulated moves and explores them further ahead, while giving up on bad moves as quickly as possible. In the old days, some programmers used to manually key in an “evaluation function” to each move, but Ito has made his computer read data from some 50,000 games — ones actually played by top professional players — in order to help the program make the right choices. And indeed, the quality of games memorized determines the quality of the program, he said.

“If you let computers memorize game records of weak players, the computers would naturally think that those are the good moves,” he said.

Asked about his computer’s chance of winning, Ito says he genuinely cannot predict the outcome, because that’s actually up to how far Yonenaga will be retrained in time for the January match. At present, top shōgi programs like Bonkras are currently at a level of lower- to middle-class professional players, he says.

Eventually, though, computers will beat the greatest shōgi players, Ito says rather matter-of-factly. Does that mean the ebbing popularity of the game will suffer further? He doesn’t think so.

“Shōgi programs and shōgi players are comparable to cars and runners,” Ito said. “We all know that cars are much faster, but we still enjoy watching track and field athletics in the Olympics. Computers also beat humans at chess, but the chess players’ championships are still popular.”

But for Ito himself, after beating a top shōgi player, he said he would probably move on to programming other games.

“My master plan is, if a shōgi computer triumphs over humans, I would start programming go, and when I’m done with go, I’d move on to mahjongg,” he said, noting that programming complexities rise in that order. “Though, by that time, I might be too old to accomplish that!”

The Yonenaga vs Bonkras match will be held at Tokyo’s Shōgi Kaikan from 10 a.m. on Jan. 14, 2012. The match can be seen live on Nico Nico Doga. Co-organizer of the match, Dwango, also plans to host a live event at Nicofarre in Tokyo’s Roppongi district. For more information, visit info.nicovideo.jp/shogi/ (Japanese only).