Crazy Stone computer Go program defeats Ishida Yoshio 9 dan with 4 stones

Crazy Stone, a computer Go program by Rémi Coulom, defeated Ishida Yoshio 9p with a four stone handicap, as part of the inaugural Denseisen at the 6th Computer Go UEC Cup in Japan (March 20, 2013).

The Computer vs the computer

It was an ironic showdown between the computer and ‘The Computer’.

Ishida was nicknamed ‘The Computer’ in his prime, because of the accuracy of his counting and endgame skills.

Ishida Yoshio

Ishida Yoshio 9 dan - 'The Computer'.

Ishida Yoshio 9 dan – ‘The Computer’.

Born in 1948, Ishida is now 64 years old.

However, back in the 70s, Ishida won the prestigious Honinbo title for an impressive five consecutive years, making him one of the top players of that era.

After the game, Ishida said that he thought the program was a ‘genius’ and marvelled at the calmness and flexibility of its moves.

In contrast, Ishida admitted that he felt frustrated at not being able to catch up.

Towards the end of the game, as Crazy Stone began to play some safety first moves that lost points, it became clear to those who are familiar with computer Go that Crazy Stone believed it had won.

We can assume that Ishida was briefed about the possibility of this happening before the game, so he wouldn’t be taken aback.

In the end, Crazy Stone won by 2.5 points.

Rémi Coulom

Coulom and Crazy Stone also won the 6th Computer Go UEC Cup a week earlier, defeating the defending champion, Zen.

Rémi Coulom (left) placing stones for his program, Crazy Stone, against Ishida Yoshio.

Rémi Coulom (left) placing stones for his program, Crazy Stone, against Ishida Yoshio.

Crazy Stone seems to be enjoying a resurgence after having previously won the 1st and 2nd Computer Go UEC Cups.

Those of you who follow computer Go will be familiar with Zen. It defeated Takemiya Masaki on four stones in 2012.

Takao Shinji’s comments

At this more recent event, Ishida also played against Zen on 4 stones. However, Zen didn’t fare as well against Ishida and, according to Takao Shinji 9p, made many unforced errors.

Takao, a former Honinbo himself, also commented on the game between Ishida and Crazy Stone.

He admired black 52, pointing out that it’s the kind of move a human would overlook (preferring to atari from the other side instead).

That’s because it would be a bad move under most circumstances, but in this case it was surprisingly effective.

Black 52: The normal move for 52 would be A, but then white would play at 52. In this case, if white connects at A, black exchanges B for C, and then captures the whole group with D. So white can only play C and, after black A, 52 is shown to be an excellent move.

Black 52: The normal move for 52 would be A, but then white would play at 52. In this case, if white connects at A, black exchanges B for C, and then captures the whole group with D. So white can only play C and, after black A, 52 is shown to be an excellent move.

Takao said that white didn’t get any other good chances after black’s excellent play (with 52 and so on) at the bottom.

A four stone handicap

For the benefit of readers who aren’t necessarily Go players, a four stone handicap means that black (the computer) was allowed to place four stones on the board before white (Ishida) made any moves.

This may sound like a lot but, while it is a significant handicap, it’s not really as big as it sounds.

Only a fairly strong amateur player can hope to defeat a professional player like Ishida Yoshio with four stones.

More to come!

The University of Electro-Communications and the Nihon Ki-in (Japanese Go Association) have teamed up to host more computer-human Go tournaments over the next five years!

This event, the Denseisen, translates literally to something like ‘electronic holy war’ 🙂

Rémi Coulom, Crazy Stone and Ishida Yoshio at the inaugural Denseisen.

Rémi Coulom, Crazy Stone and Ishida Yoshio at the inaugural Denseisen.

The nitty gritty – rules and hardware

The games were played under Japanese rules and the players were given 30 minutes main time, followed by 30 seconds per move byo-yomi (quite a fast game by professional standards).

Crazy Stone ran on a 64-core server when playing Ishida. Zen ran on a 30-core cluster of 5 PCs.

We don’t have more details about the exact specifications of the hardware at the time of writing, but if you know, please leave a comment below.

What do you think about the games?

What do you think about the games (just below)?

Did Crazy Stone’s steady play surprise you? Or are you getting more used to a world where computers are now very good at Go?

Leave a comment below to let me know what you think 🙂

Game records

Crazy Stone vs Ishida Yoshio


Download SGF File (Go Game Record)


Zen vs Ishida Yoshio


Download SGF File (Go Game Record)


Zen vs Crazy Stone


Download SGF File (Go Game Record)


Further reading

Related Articles

About Jing

Jing likes writing, and can occasionally be convinced to play a game of Go. Even though she doesn't play Go as often as she once did, she still enjoys following the professional Go scene and writing about it on Go Game Guru.

You can follow Go Game Guru on Facebook, Twitter, Google+ and Youtube.


  1. A big achievement by Crazy Stone! With another program just four stones under professional level, I’m optimistic about the future of computer Go. Higher computing power combined with more efficient algorithms will definitely push computer powers into the professional ranks within a decade.

    • It will be really interesting when they get strong enough to play pros in serious, slow play matches – at least 3 hours for each player.

      So far we’ve only seen fairly fast games against pros and if games on Go servers are anything to go by, fast games seem to tilt the tables in the computer’s favor.

      • Anonymous says:

        You are right. Fast games favor computers.
        Seeing computer-human go games gives me the same feeling I had when computer was climbing the ladder in chess! It took a few years to see IBM beating the world no.1.
        Let see how long it will take in go.


        • Fábio Emilio Costa says:

          Think what could happen if IBM programmed Watson or one of those big iron LinuxONE for playing Go with a good IA, like Crazy Stone

  2. Great news! I already use crazystone on my android tablet. I wish I had the equivalent of programs like “fritz” in chess in order to analyse my game with a reliable engine so I can understand where I went wrong etc. In chess computers are a great tool to better one’s game, I hope the same can be said for go in the near future!

  3. I like how the computer was described as remaining calm. I look forward to the day when we can truly make computers that “get nervous” over a game of go.

    • Me too Mef 😉

      Sometimes it’s cute reading the way some pros talk about a computer player, like it’s a person. Takao also said he was upset with Zen for playing such bad moves, on his blog.

  4. bobiscool says:

    hahaha I love how in the description it says “black team 64-cores”… that really made me laugh.

    It brings an interesting point though… sometime in the future, when computers have surpassed humans, I guess the next step is to try to beat a human with a single core instead of a “team” of 64 cores… Of course you’d have to also limit it to say 4 GHz or something.

    • David Ormerod says:

      We thought that was funny too, though it wasn’t intentional at first. We just needed somewhere to record and display that info and this way seemed vaguely appropriate.

      In the future, maybe we’ll see a team of pros play a computer? 🙂

      I wonder if working as a team would make the pros stronger? My guess is that it would.

  5. Mark Schreiber says:

    Ishida Yoshio was a 9p in the 1970s. What is Ishida Yoshio’s rating in 2013?

    • Anonymous says:

      He’s a 9p for ever, that’s the way professional ranks work. Of course he’s weaker now and not playing in title matches anymore, though I do see his name occasionally in the early rounds. I’m not aware of the Japanese having a rating system like the Koreans and Chinese.

  6. Mark Schreiber says:

    Then in 2013, Crazy Stone could not defeat a recently promoted 9p with 4 stones. So the article title is a bit misleading. What has Crazy Stone really achieved? Could we know how many stones Crazy Stone would need to defeat a recently promoted Japanese 9p or 1p? If there is no rating system in Japan then we cannot even guess. It would be more interesting to see Crazy Stone play on the KGS Go server.

    • David Ormerod says:

      It would be a mistake to assume that Ishida Yoshio isn’t a very strong player. He is. For a computer to beat him with a four stone handicap is very impressive. Just like Zen’s feat of beating Takemiya in 2012.

      Since the Oteai (ranking tournament) was phased out, professional dan ranks are neither here nor there. They don’t tell you much about the strength of a player, but are still mentioned out of respect (which is part of the culture surrounding the game).

      What’s more relevant than rank is that Ishida is an honorary Honinbo. A title he achieved by beating down the top players in the world for five consecutive years. Only four players have ever received that title (in the modern era) and only two of them are still alive.

      Just because he’s in his 60s doesn’t mean you can assume he’s weak. Some players have still won titles at that age.

      Today’s world champion players, the ones who are still in their prime, are too busy playing matches to play a four stone handicap game against a computer. I doubt you’ll get a one of the top 10 players to take a computer seriously until it can play them on at least two stones. At this stage, there are still plenty of amateurs who are stronger than the computer (but a lot less than there were a few years ago).

      If you want to criticize something, then the speed of the game is a better target. I think there are plenty of questions to ask there.

      • Mark Schreiber says:

        I don’t think Ishida Yoshio is playing at the level of a recently promoted 9p in 2013. The article seems to say crazy stone beat a 9p at 4 stones. Crazy stone could not beat a recently promoted 9p at 4 stones. From this game, we don’t know how strong crazy stone is. I would rather see a game without a handicap and with a rated 1p player. Then we can measure the strength of crazy stone. I agree the game was too fast. But time we can measure. 30 minutes is too fast then next time more than 30 minutes. Crazy beat Ishida Yoshio. Next time we need someone stronger than Ishida Yoshio. Who is stronger if we don’t know how strong Ishida Yoshio is?

  7. Anonymous says:

    Computers will be the death of Go sadly, the last bastion of human kind. Chess is already a dead game. Shogi is already even money with pro’s.

  8. Yikes, that Zen-Crazy Stone game is so ridiculous! Like two dead-drunk boxers slugging it out on a roller-coaster. Nowhere near even amateur 1 dan. I wouldn’t recommend anybody to train against these programs. There’s tons of people on internet Go servers willing to play for free at any level up to strong amateur 7 dan.

    As for the game with Yoshida, Crazy Stone made many stupid moves (close to not making a move at all) and hyper-ultracautious moves, which a human playing at the KGS strengths they claim would never make (examples: 76, 124, 126, 132, 140, 146, 166, 202, 224). This sort of very defensive style in a handicap game makes it tough going even for a pro, but playing against a large handicap is an excercise in patience in any case. Yoshida was about 30 points behind around move 100, 15 points behind around 166, 10 points behind at 226 and probably could have won if he tried a bit harder. Pros can usually manage to lose by half a point when they play amateurs for money. It is also difficult to play against a program, especially a Monte Carlo program, because its moves make no sense like a human’s do, and this throws off the thinking of a pro playing a program for the first time. Note that computer Go teams rarely organize multiple-game matches or rematches against the same professional opponent, because once a pro gets the hang of the program’s style he can just haul it in.