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Alpha Go Zero: How and Why It Works

tim.hibal.org

71–80 of 116 posts

Re: Alpha Go Zero: How and Why It Works

#71
post #33

If the author's here: some of the math formulas don't render correctly. In particular, 10^170 is parsed as 10^{1}70, and $5478$ shows up without TeX applied to it.

Thanks, fixed those

Another minor fix: the number of chess diagrams is at most 10^46, according to http://tromp.github.io/chess/chess.html

Re: Alpha Go Zero: How and Why It Works

#72
post #27

Can this technique be used to write a strong chess engine?

No doubt it will be very strong by human standards, but it won't be competitive with current top programs based on alpha beta (currently duking it out in the unofficial engine world championship at http://tcec.chessdom.com/live.php).

Still, it would be interesting to see if can surpass the human world champion...

Re: Alpha Go Zero: How and Why It Works

#73

Earlier quoted context omitted.

Yes. As described, all that’s needed is a way to imagine all possible moves from a game state, and check if a game state corresponds with win/tie/loss. That is possible in Tic-Tac-Toe, Chess, and Go.

Surprisingly, they haven't done it though. Wonder why. Is it because of the number of different state changes that can occur from a particular position? Maybe Go is easier to solve than chess. It would be very interesting to see a computer improve on chess openings.

First of all, Go is not 'solved'. While the AI plays better than the best humans, it does not play perfectly (nor will any AI program in the forseeable future).

If by 'solving' you mean, developing a strong AI program to play chess, I think the reason they haven't done it because chess is easier to solve than Go. The best computer chess engines are already a lot better than the best humans. Thus, there is not much to gain for Google by finding a new approach.

There have been attempts to use similar approaches for chess, but they al seemed to perform worse than the traditional approach for chess. (Alpha-beta search with a hand-written evaluation function and null-move pruning).

The differences between Go and Chess that might explain this are:

- Chess has a smaller branching factor (the number of legal moves is around 40 in a typical position in chess, whereas it's over 100 in a typical position for Go)

- A chess position is easier to evaluate. Simply counting the material already gives a decent evaluation in a lot of cases. This supplemented by hand-written rules gives a solid evaluation of a position

- The average game of chess is shorter. A game of chess lasts between 20 and 80 moves, whereas a game of Go lasts around 200 games. This makes it a lot more feasible to extend the search far enough to oversee the consequences of each move in chess when compared to Go

Re: Alpha Go Zero: How and Why It Works

#74

Are there any plans to do this for Chess? I imagine that this is an iteration of the Alpha Go engine, people working on this are very current with Alpha Go. If Chess is similar, then wouldn't DeepMind be able to bootstrap game knowledge. Perhaps this isn't a big goal, but Chess is Chess after all.

[deleted]

Re: Alpha Go Zero: How and Why It Works

#75

Earlier quoted context omitted.

Yes. As described, all that’s needed is a way to imagine all possible moves from a game state, and check if a game state corresponds with win/tie/loss. That is possible in Tic-Tac-Toe, Chess, and Go.

Surprisingly, they haven't done it though. Wonder why. Is it because of the number of different state changes that can occur from a particular position? Maybe Go is easier to solve than chess. It would be very interesting to see a computer improve on chess openings.

The Giraffe chess engine?

https://chessprogramming.wikispaces.com/Giraffe

http://www.talkchess.com/forum/viewtopic.php?t=64096

Re: Alpha Go Zero: How and Why It Works

#76

Earlier quoted context omitted.

Interestingly, the idea behind temporal difference learning is more or less the intuition behind how people price derivatives in finance. The expected value of a contract at time T, estimated at some time t expected estimate, made n months from now, of the value [12-n] months later, will also be $100 . This allows you to shrink the state space considerably. You can usually work out the payoff of a derivatives in diff…

I think the bellman equation (which is used extensively in reinforcement learning) is also taught in stochastic calculus for finance (except in the continuous form?). https://en.wikipedia.org/wiki/Hamilton%E2%80%93Jacobi%E2%80%... My memory is hazy so there might not be a real connection here.

Yes see book by oksendal

Re: Alpha Go Zero: How and Why It Works

#77
> It is interesting to see how quickly the field of AI is progressing. Those who claim we will be able to see the robot overlords coming in time should take heed - these AI's will only be human-level for a brief instant before blasting past us into superhuman territories, never to look back.

This final paragraph is just editorializing. A computer will never care about anything (including games like Go and domination of other beings) that it is not programmed to imitate care about, and will thus remain perennially unmotivated.

Also, my intuition says that gradient descent is an ugly hack and that there HAS to be some better way (like a direct way) to get at the inverse of a matrix (not just in specific cases but in the general case!), but I digress, and not being a mathematician, perhaps someone has already proved somehow that a general method to directly and efficiently invert all possible matrices is impossible

Re: Alpha Go Zero: How and Why It Works

#78
post #64
post #26

The main reason AlphaGo Zero learns so much faster than its predecessors is because it uses temporal-difference learning.[1] This effectively removes a huge amount of the value network's state space for the learning algorithm to search through, since it bakes in the assumption that a move's value ought to equal that of the best available move in the following board position, which is exactly what you'd expect for a g…

For anyone interested: Learn more on TD and RL in general from Sutton (inventor of TD-lambda) and Barto's book: http://www.incompleteideas.net/sutton/book/the-book.html Sidenote: It used to be that simply googling "sutton barto book" would bring you to the right place with the first suggested link. Now this stuff is so popular all of a sudden, I needed to consult the link I had set on my own page in order to find it.…

very good book. but it is also very old. why are they using it only now ???

Re: Alpha Go Zero: How and Why It Works

#79

Are there any plans to do this for Chess? I imagine that this is an iteration of the Alpha Go engine, people working on this are very current with Alpha Go. If Chess is similar, then wouldn't DeepMind be able to bootstrap game knowledge. Perhaps this isn't a big goal, but Chess is Chess after all.

There was a project for chess, called giraffe https://bitbucket.org/waterreaction/giraffe whose author shut it down after joining google deep mind: http://www.talkchess.com/forum/viewtopic.php?t=59003

He thinks it's only a matter of time till machine learning beats hand crafted systems like stockfish even in chess.

http://arxiv.org/abs/1509.01549

Re: Alpha Go Zero: How and Why It Works

#80

> It is interesting to see how quickly the field of AI is progressing. Those who claim we will be able to see the robot overlords coming in time should take heed - these AI's will only be human-level for a brief instant before blasting past us into superhuman territories, never to look back. This final paragraph is just editorializing. A computer will never care about anything (including games like Go and domination…

What do you mean with inverting a matrix? In the usual definition it is well studied and understood https://en.m.wikipedia.org/wiki/Invertible_matrix#Methods_of...
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