Game playing in AI

Game playing in AI

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  GAME PLAYING INAI Dr. C.V. Suresh Babu
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  (CentreforKnowledgeTransfer) institute INTRODUCTION  Game Playingis an important domain of artificial intelligence. Games don’t require much knowledge; the only knowledge we need to provide is the rules, legal moves and the conditions of winning or losing the game. https://youtu.be/ZRZGRfK-L-U
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  (CentreforKnowledgeTransfer) institute INTRODUCTION  General gameplaying (GGP) is the design of artificial intelligence programs to be able to play more than one game successfully.  For many games like chess, computers are programmed to play these games using a specially designed algorithm, which cannot be transferred to another context.  For instance, a chess-playing computer program cannot play checkers. General game playing is considered as a necessary milestone on the way to Artificial General Intelligence. https://www.youtube.com/watch?v=6eiErYh_FeY
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  (CentreforKnowledgeTransfer) institute INTRODUCTION  General videogame playing (GVGP) is the concept of GGP adjusted to the purpose of playing video games.  For video games, game rules have to be either learnt over multiple iterations by artificial players like TD- Gammon, or are predefined manually in a domain-specific language and sent in advance to artificial playerslike in traditional GGP.  Starting in 2013, significant progress was made following the deep reinforcement learning approach, including the development of programs that can learn to play Atari 2600 games as well as a program that can learn to play Nintendo Entertainment System games.
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  (CentreforKnowledgeTransfer) institute  The firstcommercial usage of general game playing technology was Zillions of Games in 1998.  General game playing was also proposed for trading agents in supply chain management thereunder price negotiation in online auctions from 2003 on
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  (CentreforKnowledgeTransfer) institute Both players tryto win the game. So, both of them try to make the best move possible at each turn. Searching techniques like BFS(Breadth First Search) are not accurate for this as the branching factor is very high, so searching will take a lot of time. So, we need another search procedures that improve:  Generate procedure so that only good moves are generated.  Test procedure so that the best move can be explored first. The most common search technique in game playing is Minimax search procedure. It is depth-first depth- limited search procedure. It is used for games like chess and tic-tac-toe.
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  (CentreforKnowledgeTransfer) institute MINIMAX ALGORITHM Minimax algorithmuses two functions  MOVEGEN : It generates all the possible moves that can be generated from the current position.  STATICEVALUATION : It returns a value depending upon the goodness from the viewpoint otwo-player https://www.youtube.com/watch?v=KU9Ch59-4vw
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  (CentreforKnowledgeTransfer) institute This algorithm isa two player game, so we call the first player as PLAYER1 and second player as PLAYER2. The value of each node is backed-up from its children. For PLAYER1 the backed-up value is the maximum value of its children and for PLAYER2 the backed-up value is the minimum value of its children. It provides most promising move to PLAYER1, assuming that the PLAYER2 has make the best move. It is a recursive algorithm, as same procedure occurs at each level.
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  Figure 1: Beforebacking-up of values Figure 2: After backing-up of values • We assume that PLAYER1 will start the game. • 4 levels are generated. • The value to nodes H, I, J, K, L, M, N, O is provided by STATICEVALUATION function. • Level 3 is maximizing level, so all nodes of level 3 will take maximum values of their children. Level 2 is minimizing level, so all its nodes will take minimum values of their children. • This process continues. • The value of A is 23. • That means A should choose C move to win.