Tag: AlphaGo

Using Strong Go Programs on Macintosh

SmartGo for Mac is not playing strongly, as computer play is using my own pre-AlphaGo engine. However, like SmartGo for Windows, you can use GTP (Go Text Protocol) to connect to strong engines to play against.

The most recent version of SmartGo for Macintosh (0.8.18) includes some improvements in how it handles GTP engines. It’s not perfect, there’s much more to be done, but hopefully it will tide you over while I keep my focus on the new SmartGo for iOS.

The first step is downloading and installing the computer go engines you want to connect to. Here are three I’ve tested with SmartGo for Mac, from easy to hard to install. All assume that you’re somewhat comfortable using the Terminal app; check out this iMore guide if you’re new to the command line.

Pachi

The easiest way to install Pachi on the Mac is using Homebrew (which you probably have to install first). Follow these instructions:

https://brewinstall.org/Install-pachi-on-Mac-with-Brew/

Leela Zero

Find Leela Zero on Github, scroll down to I just want to play with Leela Zero right now, and follow the Homebrew instructions. You’ll also have to download a file with network weights; the link is in that same section.

KataGo

Installing KataGo is more complicated, as you have to compile it yourself. Follow the instructions for Linux at https://github.com/lightvector/KataGo.

smartgo-mac-gtp-preferences

Setting Parameters

Once you’ve installed an engine, you need to add it to SmartGo. Choose SmartGo > Preferences in the menu and click on GTP. Then click on the + icon and navigate to the executable of the engine you want to add. SmartGo uses the engine name to guess reasonable parameters, then tries to run the engine to get its name and version. If you see a green checkmark with the name and version, you’re all set. Otherwise, edit the parameters sent to the GTP engine (the third column in the table). The following basic settings work for my setup:

Leela Zero: -g –playouts 1000 –noponder -w /usr/local/Cellar/leela-zero/0.17/best-network/40b_257a_64k_q

KataGo: gtp -model /Users/anders/work/katago/cpp/models/model.txt.gz -config /Users/anders/work/katago/cpp/configs/gtp_example.cfg

Leela Zero and KataGo take a while to initialize, so even just getting name and version initially can take a minute, and SmartGo may time out. If it does, just try starting a game against the engine anyway (File > New Game, specify the engine in the dropdown for Black or White), and see if it works.

I hope these instructions get you pointed in the right direction. I’m sorry none of this is as easy as it should be.

Highest Possible Pinnacle?

DeepMind announced that AlphaGo will no longer compete: “This week’s series of thrilling games with the world’s best players … has been the highest possible pinnacle for AlphaGo as a competitive program. For that reason, the Future of Go Summit is our final match event with AlphaGo.”

This reason is rubbish. Could AlphaGo repeat its string of 60 victories in no-komi games? Could it win a match giving handicap stones? If AlphaGo wanted to keep competing, there are many more challenges left for it to conquer.

DeepMind used Go as a very successful testbed for its deep learning algorithms: a testbed that has measurable outcomes and can generate its own test data. Winning against the world’s best doesn’t make that testbed obsolete. DeepMind said that this year’s version was using ten times less computing power than last year’s AlphaGo. Could they improve the algorithms by another factor of ten? Hundred? Thousand? Yes, by all means push into other domains and apply what you’ve learned, but don’t abandon the testbed. You have ideas on how to improve your learning algorithm for medical diagnosis or self-driving cars? Testing the effectiveness of those improvements will be a lot harder than in Go.

I’m glad the DeepMind team is publishing a set of 50 AlphaGo self-play games, and that they’re working on a teaching tool. But not pushing AlphaGo forward competitively is a mistake.

Moves to Unique Game

The Ke Jie vs. AlphaGo games quickly reached a position that was not in the GoGoD game collection of almost 90,000 professional game records: Game 1 was unique at move 5, game 2 was unique at move 7. To me, this seemed very early, and @badukaire on Twitter got me to wonder: How soon does a pro game usually reach a position that’s different from any previously played game?

Number of moves to unique game

Time for some data: I ran SmartGo’s fuseki matching on the whole GoGoD game collection (excluding handicap games). In that data set, the highest probability for a move to become unique is at move 8; the median is between move 11 and 12; the average is about move 13. Games are unique by move 7 in about 16% of games; by move 5 in only about 4%.

So it’s somewhat unusual to diverge from standard play that early, but there’s more variety of play early in the game than I expected. Also, I’m sure that a lot of games will soon be copying those moves by AlphaGo and Ke Jie, and those opening moves will be unique no more.

Wishful Thinking

Lee Sedol’s strategy in game 4 worked brilliantly (well explained in the excellent Go Game Guru commentary). It took AlphaGo from godlike play to kyu-level petulance. When it no longer saw a clear path to victory, it started playing moves that made no sense.

AlphaGo optimizes its chance of winning, not its margin of victory. As long as that chance of winning was good, this worked well. When the chance of winning dropped, AlphaGo’s quality of play fell precipitously. Why?

Ineffective threats

The bad moves that AlphaGo played include moves 87 and 161: threats that just don’t work, as they can easily be refuted, and either lose points, or at least reduce future opportunities. When AlphaGo plays such a move, it’s smart enough to find the correct local answer and figure out that the move doesn’t actually work. However, the Monte Carlo Tree Search component (MCTS) will also look at other moves that don’t answer that threat, as there is always a chance that the opponent plays elsewhere. Thus AlphaGo sees a non-zero chance that this threat actually works, and the way MCTS calculates the statistics it thinks that this increases its chance of winning.

Of course, the opposite is true. Playing a threat that can easily be refuted is just wishful thinking. The value network would figure out that such an exchange actually makes the position worse, but it doesn’t know that it should override the Monte Carlo simulations in this case.

Adjusting komi

One way to avoid this effect is to internally adjust the komi until the program has a good chance of winning. This causes the program to play what it thinks are winning moves, while in fact it will lose by the few points you artificially adjusted the score. If the opponent makes a mistake, the program might regain a real winning position later. (SmartGo uses this technique; it also helps play more reasonable moves in handicap games.)

For AlphaGo, that technique won’t work well: as I understand it, the value network is trained to recognize whether positions are good for Black or for White, not by how many points a player is ahead.

Known unknowns

Another idea is to look at the source of uncertainty in MCTS. The Monte Carlo winning percentages are based on statistics from the playouts, and there are many uncertainties in that process due to the random nature of the playouts and the limited nature of the search. The more moves you look at, the smaller the unknowns become, and the statistical methods used to figure out which moves to explore more deeply and how to back up results in the search tree try to minimize these uncertainties.

However, whether the opponent will answer a threat is a yes-or-no decision; it should not be treated like a statistical unknown. In that case, you want to back up the results in the tree using minimax, not percentages. Something for the DeepMind team to work on before they challenge Ke Jie, so AlphaGo won’t throw another tantrum.

AlphaGo Don’t Care

AlphaGo is badass. Like the honey badger, AlphaGo just don’t care.

Lee Sedol may have underestimated AlphaGo in game 1, but he knew what he was up against in game 2. I watched Michael Redmond’s commentary during the game, then Myungwan Kim’s commentary this morning. The Go Game Guru commentary is also very helpful.

The tenuki at move 13: Professionals always extend at the bottom first? AlphaGo don’t care. It builds a nice position at the top instead.

The peep at move 15: This is usually played much later in the game, and never without first extending on the bottom. AlphaGo don’t care. It adds 29 later, and makes the whole thing work with the creative shoulder hit of 37. It even ends up with 10 points of territory there.

With 64 and 70, Lee Sedol made his group invulnerable to prepare for a fight at the top. AlphaGo don’t care, it just builds up its framework, and then shows a lot of flexibility in where it ends up with territory.

Lee Sedol threatens the territory at the top with 166? AlphaGo don’t care, it just secures points in the center instead. Points are points, it doesn’t matter where on the board they are.

What can Lee Sedol do in the next games? I think he needs to get a complicated fight going early in the game, start ko fights, in general increase the complexity. But I fear AlphaGo just won’t care.