Monte Carlo Tree Search
A search algorithm used for decision-making in some AI systems, mentioned as the planning component on top of the neural network in the AlphaGo hybrid system.
First Mentioned
9/13/2025, 5:47:57 AM
Last Updated
9/13/2025, 5:50:44 AM
Research Retrieved
9/13/2025, 5:50:44 AM
Summary
Monte Carlo Tree Search (MCTS) is a heuristic search algorithm in artificial intelligence, designed for decision-making in complex scenarios, particularly those with vast search spaces like board games. It operates by iteratively building a search tree, balancing the exploration of new possibilities with the exploitation of known promising paths through a process involving selection, expansion, simulation (playout), and backup. First named in 2006 by Rémi Coulom, MCTS has roots in stochastic tree search methods from the late 1980s. Its effectiveness was famously demonstrated when combined with neural networks in DeepMind's AlphaGo, AlphaGo Zero, and AlphaZero, enabling them to achieve superhuman performance in games like Go, Chess, and Shogi. Beyond games, MCTS finds applications in robotics, cybersecurity, text generation, and industrial research for smart factories, extending the capabilities of AI in challenging domains, although its computational intensity and limitations in ill-defined or extremely vast search spaces require careful consideration.
Referenced in 1 Document
Research Data
Extracted Attributes
Type
Heuristic search algorithm
Field
Artificial Intelligence, Computer Science
Purpose
Decision-making processes, game playing, solving sequential decision problems
Mechanism
Intelligent tree search, balances exploration and exploitation, uses random sampling/simulations, incrementally builds a search tree
Advantages
Effective for problems with vast search spaces, extends AI capabilities, performs reasonably well on difficult problems
Core Steps
Selection, Expansion, Simulation (Playout/Rollout), Backup
Limitations
Computationally intensive, may struggle in domains with ill-defined state transitions or extremely vast search spaces, requires problem-specific modifications for complex/real-time applications
Timeline
- Roots of Monte Carlo Tree Search can be traced to research into stochastic tree search methods for two-player games. (Source: Web Search (diva-portal.org))
1980s (late)
- Rémi Coulom described the application of the Monte Carlo method to game-tree search and coined the name 'Monte Carlo tree search'. Independently, L. Kocsis and Cs. Szepesvári developed the UCT (Upper Confidence bounds applied to Trees) algorithm, and S. Gelly et al. implemented UCT in their program MoGo. (Source: Web Search (Wikipedia, diva-portal.org))
2006
- The MoGo program, utilizing UCT, achieved dan (master) level in 9x9 Go. The Fuego program also began to win against strong amateur players in 9x9 Go. (Source: Web Search (Wikipedia))
2008
- MCTS was famously used in DeepMind's AlphaGo and its successors, AlphaGo Zero and AlphaZero, where it was combined with neural networks to achieve human-level performance in games like Go, Chess, and Shogi. (Source: Summary, Related Documents, Web Search)
After 2008
Web Search Results
- What is Monte Carlo Tree Search (MCTS)? | TEDAI San Francisco
Monte Carlo Tree Search (MCTS) is a heuristic algorithm used in AI decision-making processes, particularly in complex situations. It employs intelligent tree search techniques to assist AI in making informed choices. MCTS is widely applied in various domains such as game simulation, robotics, and security. In MCTS, nodes symbolize states or problem configurations, while edges signify transitions between these states. The algorithm's fundamental steps include selection, expansion, simulation, and backup, which collectively contribute to decision-making processes by evaluating potential outcomes and selecting the most favorable path.
- Monte Carlo Tree Search: A Guide | Built In
Monte Carlo tree search (MCTS) is a heuristic search algorithm for decision processes. Here’s what you need to know.
- Monte Carlo Tree Search: A Review of Recent Modifications and Applications
Abstract page for arXiv paper 2103.04931: Monte Carlo Tree Search: A Review of Recent Modifications and Applications
- Monte Carlo Tree Search: The Game-Changing Algorithm behind DeepMind's AlphaGo
Explore Game AI: Dive into AlphaGo, tree search algorithms, and Monte Carlo Tree Search (MCTS) for a deeper understanding of AI in gaming.
- The Animated Monte-Carlo Tree Search (MCTS)
The Animated Monte-Carlo Tree Search (MCTS) The algorithm at the heart of AlphaGo, AlphaGo Zero, AlphaZero and MuZero Monte-Carlo Tree Search (MCTS) is a heuristic search method, whose main purpose …
- Monte Carlo tree search - Wikipedia
In computer science, Monte Carlo tree search (MCTS) is a heuristic "Heuristic (computer science)") search algorithm for some kinds of decision processes, most notably those employed in software that plays board games. In that context MCTS is used to solve the game tree. [...] The focus of MCTS is on the analysis of the most promising moves, expanding the search tree based on random sampling of the search space. The application of Monte Carlo tree search in games is based on many playouts, also called roll-outs. In each playout, the game is played out to the very end by selecting moves at random. The final game result of each playout is then used to weight the nodes in the game tree so that better nodes are more likely to be chosen in future playouts. [...] In 2006, inspired by its predecessors, Rémi Coulom described the application of the Monte Carlo method to game-tree search and coined the name Monte Carlo tree search, L. Kocsis and Cs. Szepesvári developed the UCT (Upper Confidence bounds applied to Trees) algorithm, and S. Gelly et al. implemented UCT in their program MoGo. In 2008, MoGo achieved dan "Dan (rank)") (master) level in 9×9 Go, and the Fuego program began to win against strong amateur players in 9×9 Go.
- ML | Monte Carlo Tree Search (MCTS) - GeeksforGeeks
Monte Carlo Tree Search (MCTS) is a algorithm designed for problems with extremely large decision spaces, like the game Go with its 10170possible board states. Instead of exploring all moves, MCTS incrementally builds a search tree using random simulations (rollouts) to guide its decisions. It balances exploration of new possibilities and usage of known promising paths, effectively focusing computational effort where it matters most, making it highly efficient for complex decision-making tasks.
- Monte Carlo Tree Search: A Review of Recent Modifications and ...
> Abstract:Monte Carlo Tree Search (MCTS) is a powerful approach to designing game-playing bots or solving sequential decision problems. The method relies on intelligent tree search that balances exploration and exploitation. MCTS performs random sampling in the form of simulations and stores statistics of actions to make more educated choices in each subsequent iteration. The method has become a state-of-the-art technique for combinatorial games, however, in more complex games (e.g. those with
- [PDF] The Multiple Uses of Monte-Carlo Tree Search
Monte Carlo Tree Search (MCTS) is a relatively new Artificial Intelligence (AI) algorithm that has gained significant attention and success in the field of games. The algorithm has been described as a general-purpose heuristic, a search process that can be applied to a wide range of different problems and applications and remain quite effective within all of them. This paper will look at a recent increase in interest in this algorithm from within industrial research. It will look at the topics [...] 2. Literature Review Monte Carlo algorithms, or algorithms with a stochastic component, are at least as old as modern computers. Monte Carlo Tree Search is a relatively recent addition to this collection. It has its roots in research conducted in the late 1980s into stochastic tree search methods for two-player games and was received its current name 2006 . [...] is a relatively recent Artificial Intelligence algorithm, sometimes described as a general-purpose heuristic, that has been found to be very effective in several theoretical and game-related problems. This paper will review the current growth in research into possible industrial applications of this algorithm and how a framework utilising this algorithm can help to realise the aims of the smart factory vision.
- [PDF] Monte Carlo Tree Search and Its Applications - GitHub Pages
Monte Carlo Tree Search and Its Applications Max Magnuson Division of Science and Mathematics University of Minnesota, Morris Morris, Minnesota, USA 56267 magnu401@morris.umn.edu ABSTRACT Monte Carlo tree search (MCTS) is a probabilistic algorithm that uses lightweight random simulations to selectively grow a game tree. MCTS has experienced a lot of success in do-mains with vast search spaces which historically have chal-lenged deterministic algorithms . This paper discusses the steps of the [...] CONCLUSIONS The Monte Carlo tree search algorithm has been very suc-cessful in extending the capabilities of AI. MCTS performs reasonably well on problems with vast search spaces, which were very difficult for previous algorithms. Before MCTS, AI struggled to defeat low rank amateurs in Go. Now with MCTS, AI can compete with high level pros . Also, MCTS has demonstrated its effectiveness in generating narratives, another problem with vast search spaces . [...] BACKGROUND MCTS combines the random sampling of traditional Monte Carlo methods with tree searching. Monte Carlo methods use repeated random sampling to obtain results. In MCTS, the random sampling is in the form of random simulations which are used to expand the game tree. The game tree is then used to decide the next move.