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Unformatted text preview: CS 2710 Foundations of AI CS 2710 Foundations of AI Lecture 2 Milos Hauskrecht milos@cs.pitt.edu 5329 Sennott Square Problem solving by searching CS 2710 Foundations of AI Example Assume a problem of computing the roots of the quadratic equation Do you consider it a challenging problem? 2 = + + c bx ax CS 2710 Foundations of AI Example Assume a problem of computing the roots of the quadratic equation Do you consider it a challenging problem? Hardly we just apply the standard formula: a ac b b x 2 4 2 2 , 1 = 2 = + + c bx ax CS 2710 Foundations of AI Solving problems by searching Some problems have a straightforward solution Just apply the formula, or follow a standardized procedure Example: solution of the quadratic equation Hardly a sign of intelligence More interesting problems require search : more than one possible alternative needs to be explored before the problem is solved the number of alternatives to search among can be very large, even infinite. CS 2710 Foundations of AI Search example: Traveler problem Find a route from one city ( Arad ) to the other ( Bucharest ) CS 2710 Foundations of AI Example. Traveler problem Another flavor of the traveler problem: find the route with the minimum length between S and T CS 2710 Foundations of AI Example. Puzzle 8. Find the sequence of the empty tile moves from the initial game position to the designated target position Initial position Goal position CS 2710 Foundations of AI Example. Nqueens problem. Find a configuration of n queens not attacking each other Goal configuration Bad goal configuration CS 2710 Foundations of AI A search problem is defined by : Search space : The set of objects among which we search for the solution Example: objects = routes between cities, or Nqueen configurations Goal condition What are the characteristics of the object we want to find in the search space? Examples: Path between cities A and B Path between A and B with the smallest number of links Path between A and B with the shortest distance Nonattacking nqueen configuration CS 2710 Foundations of AI Search Search (process) The process of exploration of the search space The efficiency of the search depends on: The search space and its size Method used to explore (traverse) the search space...
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 Fall '11
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 Artificial Intelligence

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