Questions tagged [alphazero]

For questions related to DeepMind's AlphaZero, which is a computer program that can play Go, Chess, and Shogi. AlphaZero achieved, within 24 hours of training, a superhuman level of play in these three games by defeating world-champion programs Stockfish, Elmo, and the 3-day version of AlphaGo Zero. AlphaZero was introduced in "Mastering Chess and Shogi by Self-Play with a General Reinforcement Learning Algorithm" (2017) by David Silver et al.

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Does the AlphaZero algorithm keep the subtree statistics after each move during MCTS?

This question is regarding the Monte Carlo Tree Search (MCTS) algorithm presented in the AlphaZero paper (arXiv). As described in the paper, each MCTS used 800 simulations to determine the next action....
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What can we learn from AlphaZero in the development towards AGI?

According to DeepMind, AlphaZero's creative insights coupled with the encouraging results we see in other projects such as AlphaFold, give us confidence in our mission to create general purpose ...
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How can AlphaZero be used in other industries besides gaming?

I'm an AI Engineering student from Belgium and I'm writing my bachelor thesis on the creation of a chess computer with deep reinforcement learning based on AlphaZero. My implementation can be found ...
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Can AlphaZero develop significantly different playing styles (depending on the random games from which it learrns)?

There is a quite popular video analysing a chess game AlphaZero vs. AlphaZero, called "the perfect game". It leaves some questions open and I'd like to ask them here: Did the two copies of ...
1 vote
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Examples of rationalizable AI

The marvelous book Game Changer: AlphaZero's Groundbreaking Chess Strategies and the Promise of AI gave rise to this question. It is - in my opinion - a perfect example of rationalizing a piece of AI ...
2 votes
2 answers
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Does AlphaGo play random moves in a real competition?

Alphago and AlphaGo zero use random play to generate data and use the data to train DNN. "Random play" means that there is a positive probability for AlphaGo to play some suboptimal moves ...
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What is a policy training target in AlphaZero?

In AlphaZero's attached pseudocode, they create a training target for the policy network in this way. ...
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187 views

Would AlphaZero work just with a value network?

There is a nice post about the intuition why AlphaZero works. One of the advantages of using a policy network in the games where a perfect simulator is available (such as chess) is to save computation ...
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What does it mean there is no rollout in AlphaZero's training?

According to a blog post by DeepMind, AlphaZero doesn't have a real rollout. AlphaGo Zero does not use "rollouts" - fast, random games used by other Go programs to predict which player will ...
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At what point are MCTS results discarded in AlphaZero Training?

Regarding the AlphaZero paper, it is not clear to me when the Monte Carlo Tree Search (MCTS) results will be cleaned up. I assume this has to happen at some point, since mixing results could lead to ...
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How does policy network learn in AlphaZero?

I'm currently trying to understand how AlphaZero works. There is one thing with the training of the AlphaZero's policy head that confuses me. Basically, in AlphaGo Zero's paper (where the major part ...
3 votes
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Why does Alpha Zero's Neural Network flip the board to be oriented towards the current player?

While reading the AlphaZero paper in preparation to code my own RL algorithm to play Chess decently well, I saw that the "The board is oriented to the perspective of the current player." I ...
4 votes
1 answer
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How does the Alpha Zero's move encoding work?

I am a beginner in AI. I'm trying to train a multi-agent RL algorithm to play chess. One issue that I ran into was representing the action space (legal moves/or honestly just moves in general) ...
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1 answer
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Clarifying representation of Neural Nerwork input for Chess Alpha Zero

In the Alpha Zero paper (https://arxiv.org/pdf/1712.01815.pdf) page 13, the input for the NN is described. In the beggining of the page, the authors state that: "The input to the Neural Network ...
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Is it practical to train AlphaZero or MuZero (for indie games) on a personal computer?

Is it practical/affordable to train an AlphaZero/MuZero engine using a residential gaming PC, or would it take thousands of years of training for the AI to learn enough to challenge humans? I'm having ...
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What is the consensus on the "correct" temperature settings for the AlphaZero algorithm?

In the AlphaZero learning algorithm, during self-play to generate training games, the move played is chosen with probability proportional to the MCTS visits raised to the $\tau$-th power, where $\tau$ ...
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Do AlphaZero/MuZero learn faster in terms of number of games played than humans?

I don't know much about AI and am just curious. From what I read, AlphaZero/MuZero outperform any human chess player after a few hours of training. I have no idea how many chess games a very talented ...
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Alpha Zero does not converge for Connect 6, a game with huge branching factor - why?

I have a problem with applying alpha zero self-play to a game (Connect 6) with a huge branching factor (30,000 on average). I have implemented the MCTS as described but I found that during the MCTS ...
4 votes
1 answer
519 views

How does AlphaZero's MCTS work when starting from the root node?

From the AlphaGo Zero paper, during MCTS, statistics for each new node are initialized as such: ${N(s_L, a) = 0, W (s_L, a) = 0, Q(s_L, a) = 0, P (s_L, a) = p_a}$. The PUCT algorithm for selecting ...
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Are inputs into AlphaZero the same during the evaluate step in MCTS and during test time?

From the AlphaZero paper: The input to the neural network is an N × N × (M T + L) image stack that represents state using a concatenation of T sets of M planes of size N × N . Each set of planes ...
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1 answer
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Is there a training data capacity limit for AlphaZero (Chess)?

In AlphaZero, we collect ($s_t, \pi_t, z_t$) tuples from self-play, where $s_t$ is the board state, $\pi_t$ is the policy, and $z_t$ is the reward from winning/losing the game. In other DeepRL off-...
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Stack of Planes as the Action Space Representation for AlphaZero (Chess)

I have a question regarding the action space of the policy network used in AlphaZero. From the paper: We represent the policy π(a|s) by a 8 × 8 × 73 stack of planes encoding a probability ...
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In AlphaZero, do we need to store the data of terminal states?

I have a question about the training data used during the update/back-propagation step of the neural network in AlphaZero. From the paper: The data for each time-step $t$ is stored as ($s_t, \pi_t, ...
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What would be the AlphaGo's performance in continuous action space?

During my research for Google DeepMind's Go-playing program Alpha Go and its successor Alpha Go Zero, I discovered that the system uses a clever pipeline and an interplay of blocks of both policy and ...
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AlphaGo Zero: does $Q(s_t, a)$ dominate $U(s_t, a)$ in difficult game states?

AlphaGo Zero AlphaGo Zero uses a Monte-Carlo Tree Search where the selection phase is governed by $\operatorname*{argmax}\limits_a\left( Q(s_t, a) + U(s_t, a) \right)$, where: the exploitation ...
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Is which sense was AlphaGo "just given a rule book"?

I was told that AlphaGo (or some related program) was not explicitly taught even the rules of Go -- if it was "just given the rulebook", what does this mean? Literally, a book written in ...
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What happens when an opponent a neural network is playing with does not obey the rules of the game (i.e. cheats)?

For example, if AlphaZero plays with an opponent who has a right to move chess figures any way she wants, or make more than 1 move in a turn? Will a neural network adapt to that, as it adapted to an ...
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In Alpha(Go)Zero, why is the policy extracted from MCTS better than the network one?

I've read through the Alpha(Go)Zero paper and there is only one thing I don't understand. The paper on page 1 states: The MCTS search outputs probabilities π of playing each move. These search ...
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1 answer
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Can AlphaZero considered as Multi-Agent Deep Reinforcement Learning?

Can AlphaZero considered as Multi-Agent Deep Reinforcement Learning? I could not find a clear answer on this. I would say yes it is Multi Agent Learning, as there are two Agents playing against each ...
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What kind of policy evaluation and policy improvement AlphaGo, AlphaGo Zero and AlphaZero are using

I'm trying to find out what kind of policy improvement and policy evaluation AlphaGo, AlphaGo Zero, and AlphaZero are using. By looking into their respective paper and SI, I can conclude that it is a ...
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Where does reinforcement learning actually show up in Deepmind's game engines?

From the brief research I've done on the topic, it appears that the way Deepmind's Alphazero or Muzero makes decisions is through Monte Carlo tree searches, where in the randomized simulations allows ...
3 votes
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Is Monte Carlo tree search needed in partially observable environments during gameplay?

I understand that with a fully observable environment (chess / go etc) you can run an MCTS with an optimal policy network for future planning purposes. This will allow you to pick actions for gameplay,...
1 vote
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How to encode board before input into the neural net?

Currently I'm working on an educational project (implementation of AlphaZero approach to different types of board games). My biggest concern at the moment is how to encode board before input into the ...
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1 answer
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In AlphaZero, which policy is saved in the dataset, and how is the move chosen?

I've been doing some research on the principles behind AlphaZero. Especially this cheat sheet (1) and this implementation (2) (in Connect 4) were very useful. Yet, I still have two important questions:...
2 votes
1 answer
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Building 'evaluation' neural networks for go, reversi, checkers etc, how to train?

I'm trying to build neural networks for games like Go, Reversi, Othello, Checkers, or even tic-tac-toe, not by calculating a move, but by making them evaluate a position. The input is any board ...
5 votes
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547 views

How is the rollout from the MCTS implemented in both of the AlphaGo Zero and the AlphaZero algorithms?

In the vanilla Monte Carlo tree search (MCTS) implementation, the rollout is usually implemented following a uniform random policy, that is, it takes random actions until the game is finished and only ...
1 vote
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AlphaZero value at root node not being affected by training

I have written my own AlphaZero implementation and started training it recently. Problem is, I am 99% sure there is a mistake and I do not know how to tackle this, since I cannot explain it. I am new ...
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When does AlphaZero play suboptimal moves?

If AlphaZero was always playing the best moves it would just generate the same training game over and over again. So where does the randomness come from? When does it decide not to play the most ...
2 votes
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Alphazero Value loss doesn't decrease

Currenly I'm trying to reimplement alphazero in pure c++ using libtorch to accomodate my project's need. But when I training my model, I found out that the value loss doesn't decrese at all after even ...
2 votes
1 answer
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What does it mean for AlphaZero's network to be "fully trained"

Reading this blog post about AlphaZero: https://deepmind.com/blog/article/alphazero-shedding-new-light-grand-games-chess-shogi-and-go It uses language such as "the amount of training the network ...
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What's missing from Alpha Zero to make it generally intelligent?

Alpha Zero is the game playing AI. One might try to use the algorithm in a robot which takes input from it's environment and thinks about taking the best course of action. So I was thinking about ...
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Alpha Zero queen promotion

"The final 9 planes encode possible underpromotions for pawn moves or captures in two possible diagonals, to knight, bishop or rook respectively. Other pawn moves or captures from the ...
4 votes
1 answer
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How can I use one neural network for both players in Alpha Zero (Connect 4)?

First of all, it is great to have found this community! I am currently implementing my own Alpha Zero clone on Connect4. However, I have a mental barrier I cannot overcome. How can I use one neural ...
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8 votes
1 answer
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Does AlphaZero use Q-Learning?

I was reading the AlphaZero paper Mastering Chess and Shogi by Self-Play with a General Reinforcement Learning Algorithm, and it seems they don't mention Q-Learning anywhere. So does AZ use Q-...
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3 votes
1 answer
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What knowledge is required for understanding the AlphaZero paper?

My goal is to understand AlphaZero paper published by deepmind. I'm beginning my journey trying to get the basic intuition of reinforcement learning from the book by Barto and Sutton. As per my ...
1 vote
1 answer
138 views

How to deal with invalid output in a policy network? [duplicate]

I am interested in creating a neural network-based engine for chess. It uses a $8 \times 8 \times 73$ output space for each possible move as proposed in the Alpha Zero paper: Mastering Chess and Shogi ...
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How does AlphaZero use its value and policy heads in conjunction?

I have a question about how the value and policy heads are used in AlphaZero (not Alphago Zero), and where the leaf nodes are relative to the root node. Specifically, there seem to be several possible ...
3 votes
1 answer
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Alphazero policy head loss not decreasing

I am now working on training an alphazero player for a board game. The implementation of board game is mine, MCTS for alphazero was taken elsewhere. Due to complexity of the game, it takes a much ...
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8 votes
2 answers
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How can alpha zero learn if the tree search stops and restarts before finishing a game?

I am trying to understand how alpha zero works, but there is one point that I have problems understanding, even after reading several different explanations. As I understand it (see for example https:/...
1 vote
3 answers
1k views

Combining deep reinforcement learning with alpha-beta pruning

I will explain my question in relation to chess, but it should be relevant for other games as well: In short terms: Is it possible to combine the techniques used by AlphaZero with those used by, say, ...