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Game Playing and Adversarial search techniques

Game playing in AI involves designing algorithms that can play games (e.g., chess, tic-tac-toe) against human players or other AI systems.

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  • These games typically involve two players (adversaries) who take turns, and the goal is to find the best move to maximize the chances of winning.
  • The most common search technique in game playing is Minimax search procedure.

Key Concepts:

  • Adversarial Nature: The opponent’s moves are unpredictable, so the algorithm must plan for all possible moves.
  • Decision-Making: The AI must evaluate the current state of the game and choose the best action to achieve a winning outcome.

Adversarial search techniques are algorithms used in two-player games where the players have opposing goals.

  • These techniques explore the possible moves of both players to determine the best strategy.

Key Concepts:

  • Search Tree: Represents all possible moves and countermoves in the game.
  • Mini-Max Algorithm: A foundational technique for adversarial search.
  • Alpha-Beta Pruning: An optimization of the Mini-Max algorithm to reduce the number of nodes evaluated.

1.) Mini-Max Search

    Mini-Max is an adversarial search algorithm used in two-player games to determine the optimal move for a player, assuming the opponent also plays optimally.

    How it Works:

    The algorithm alternates between two players:

    • Maximizing Player: Tries to maximize its own score.
    • Minimizing Player: Tries to minimize the opponent’s score.

    It explores the game tree to evaluate all possible moves and countermoves, assigning a value to each terminal state (win, lose, or draw).

    Example:

    • In tic-tac-toe, Mini-Max evaluates all possible moves to ensure a win or at least a draw.

    2.) Alpha-Beta Pruning:

      Alpha-Beta Pruning is an optimization of the Mini-Max algorithm that reduces the number of nodes evaluated in the search tree by pruning branches that cannot influence the final decision.

      How it Works:

      • It uses two values, alpha (the best value for the maximizing player) and beta (the best value for the minimizing player), to eliminate unnecessary branches.
      • If a branch is found to be worse than the current best option, it is pruned (not explored further).

      Example:

      • In chess, Alpha-Beta Pruning avoids evaluating moves that are clearly worse than previously explored moves.

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