Artificial Intelligence
12 minutes


AlphaGo beat the Go world champion, Lee Sedol by 4 games to 1 in 2016

AlphaGo is a computer program developed by Google's DeepMind that became the first computer program to defeat a professional human player in the ancient Chinese board game, Go. The victory was seen as a major milestone in the field of artificial intelligence (AI) and brought renewed attention to the potential of deep learning techniques to tackle complex problems.

AlphaGo used a combination of machine learning techniques, including deep neural networks* and Monte Carlo tree search**, to analyze the game and make decisions about the best moves to make. The program was trained using a large dataset of expert Go players, allowing it to learn from the best human strategies.

The AlphaGo system played its first match against a human professional player in October 2015, defeating the European Go champion, Fan Hui, in five games out of five. The victory was seen as a major breakthrough, as Go is considered to be one of the most complex board games in the world, with more possible positions than there are atoms in the universe.

In March 2016, AlphaGo took on the world champion, Lee Sedol, in a best-of-five series of matches. Despite being widely regarded as one of the greatest Go players of all time, Sedol was defeated by AlphaGo in four out of five games. The victory demonstrated the potential of machine learning techniques to outperform human experts in complex games and highlighted the rapid progress being made in the field of AI.

AlphaGo has since been succeeded by even more powerful AI systems, such as AlphaZero, which can learn to play multiple games without any human input. These systems are paving the way for new applications of AI in areas such as healthcare, finance, and transportation, and are helping to advance our understanding of the capabilities and limitations of intelligent machines.

* Deep neural networks (DNNs) are a subset of artificial neural networks (ANNs) that are used in machine learning and artificial intelligence applications. DNNs are inspired by the structure and function of the human brain, which is made up of interconnected neurons that process information.

A DNN consists of multiple layers of interconnected artificial neurons, with each layer responsible for processing a different aspect of the input data. The first layer is the input layer, which receives the raw data. The middle layers are the hidden layers, which perform the majority of the processing, and the final layer is the output layer, which produces the network's prediction or classification.

During the training process, the DNN learns to recognize patterns in the input data by adjusting the strength of the connections between the neurons. This is done by minimizing a cost function that measures the difference between the network's predictions and the true values. This process is typically done using an algorithm called backpropagation, which adjusts the weights of the connections between the neurons based on the error in the output.

The term "deep" in DNNs refers to the fact that these networks have many layers, which allows them to learn more complex features and patterns in the input data. This is in contrast to shallow neural networks, which have fewer layers and may not be able to capture as much information.

DNNs have been used in a wide range of applications, including image and speech recognition, natural language processing, and game playing. They have also been used in the development of autonomous vehicles and other robotics applications. DNNs have shown great promise in improving the accuracy and efficiency of these tasks, and they continue to be an active area of research in the field of artificial intelligence.

** Monte Carlo Tree Search (MCTS) is a method used in artificial intelligence (AI) for decision-making in complex problems. The basic idea of MCTS is to simulate a large number of possible moves or game outcomes, and then select the move that has the highest probability of leading to a win. This is done by building a tree of possible game states, starting from the current game state, and then simulating random moves until the game is over. The results of these simulations are then used to guide the search towards the most promising moves.

MCTS consists of four main steps:

  1. Selection: Starting from the root of the tree, select the most promising node based on a formula that balances exploration and exploitation. This involves evaluating the nodes based on how often they have been visited and how successful they have been in previous simulations.
  2. Expansion: Once a promising node has been selected, add one or more child nodes to the tree representing the possible moves that can be made from the current game state.
  3. Simulation: Simulate a random game from the newly added child node until it reaches an end state, such as a win or loss.
  4. Backpropagation: Update the statistics of the nodes that were visited during the simulation by incrementing their visit count and win count. This information is used to update the selection criteria for future iterations of the algorithm.

By repeating these steps many times, MCTS is able to build a search tree that represents the most promising moves for the current game state. This tree is then used to select the move with the highest probability of leading to a win.

MCTS has been successful in producing some of the strongest AI players in various games. It is a powerful method for decision-making in complex problems, and it has potential applications in other fields such as robotics and logistics.

With thanks to Chat GPT

March 2, 2023

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