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Please pick up a copy of the course syllabus from the front desk. http://www.pami.uwaterloo.ca/~khoury/ece457 ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 1 Introduction to AI ECE457 Applied Artificial Intelligence Fall 2007 Lecture #1 Outline What is an AI? Russell & Norvig, chapter 1 Agents Environments Russell & Norvig, chapter 2 ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 3 Artificial Intelligence Artificial intelligence is all around us Computer players in video games Robotics Expert systems Assembly-line robots, auto-pilot, Mars exploration robots, RoboCup, etc. Medical diagnostics, business advice, technical help, etc. Natural language Spam filtering, translation, document summarization, etc. ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 4 What is an AI? Systems that… Humanly Neural Think networks ELIZA Rationally Theorem proving Deep Blue Act Rationality vs. Humans: emotions, instincts, etc. Thinking vs. acting: Turing test vs. Searle’s Chinese room Engineers (and this course) focus mostly on rational systems ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 5 Act Rationally Perceive the environment, and act so as to achieve one’s goal Not necessary to do the best action There’s not always an absolutely best action There’s not always time to find the best action An action that’s good enough can be acceptable Example: Game playing Sample approach: Tree-searching strategies Problem: Choosing what to do given the constraints ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 6 Think Rationally Uses logic to reach a decision or goal via logical inferences Example: Theorem proving Sample approach: First-order logic Problems: Informal knowledge Uncertainty Search space ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 7 Think Rationally 1. 2. 3. X = Y/Z XZ = Y X=Y X+Z=Y+Z X*Y+X*Z X * (Y + Z) a. b. c. d. e. 4. 5. 6. b² = AH * c a² = BH * c a² + b² = BH * c + AH * c a² + b² = c * (AH + BH) a² + b² = c² b/c = AH/b a/c = BH/a AH + BH = c ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 8 Act Humanly “Turing-test” AI Improve human-machine interactions up to human-human level Drawbacks: In some cases, requires dumbing down the AI Lots of man-made devices work well because they don’t imitate nature ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 9 Think Humanly Cognitive science Neural networks Helps in other fields Computer vision Natural language processing ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 10 Rational Agents An agent has A rational agent has an agent program that allows it to do the right action given its precepts ECE457 Applied Artificial Intelligence Sensors Actions Percepts Sensors to perceive its environment Actuators to act upon its environment Environment Actuators Agent Program R. Khoury (2007) Page 11 Types of Agents Simple reflex agent Model-based agent Considers what will happen given its actions Utility-based agent Keeps track of perception history Goal-based agent Selects action based only on current perception of the environment Adds the ability to choose between conflicting/uncertain goals Learning agent Adds the ability to learn from its experiences ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 12 Simple Reflex Agent Environment Percepts Actions Actuators Sensors Current State Selected Action If-then Rules ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 13 Simple Reflex Agent Dune II (1992) units were simple reflex agents Harvester rules: ECE457 Applied Artificial Intelligence IF at refinery AND not empty THEN empty IF at refinery AND empty THEN go harvest IF harvesting AND not full THEN continue harvesting IF harvesting AND full THEN go to refinery IF under attack by infantry THEN squash them R. Khoury (2007) Page 14 Model-Based Agent Environment Percepts Actions Actuators Sensors Current State Previous perceptions Selected Action World changes Impact of actions ECE457 Applied Artificial Intelligence R. Khoury (2007) If-then Rules Page 15 Goal-Based Agent Environment Percepts Actions Actuators Sensors Current State Previous perceptions State if I do action X Selected Action World changes Goal Impact of actions ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 16 Utility-Based Agent Environment Percepts Actions Actuators Sensors Current State Previous perceptions State if I do action X Happiness in that state World changes Selected Action Utility Impact of actions ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 17 Learning Agent Environment Percepts Actions Actuators Sensors Performance Element Critic Feedback Knowledge Changes Learning Problem Element Learning Goals Generator ECE457 Applied Artificial Intelligence Performance standard R. Khoury (2007) Page 18 Properties of the Environment Fully observable vs. partially observable Deterministic vs. stochastic vs. strategic See everything vs. hidden information Chess vs. Stratego Controlled by agent vs. randomness vs. multiagents Sudoku vs. Yahtzee vs. chess Episodic vs. sequential Independent episodes vs. series of events Face recognition vs. chess ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 19 Properties of the Environment Static vs. dynamic vs. semi-dynamic Discrete vs. continuous World waits for agent vs. world goes on without agent vs. world waits but agent timed Translation vs. driving vs. chess with timer Finite distinct states vs. uninterrupted sequence Chess vs. driving Single agent vs. cooperative vs. competitive Alone vs. team-mates vs. opponents Sudoku vs. sport team vs. chess ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 20 Properties of the Environment Crossword Puzzle Monopoly Fully observable, stochastic, sequential, static, discrete, competitive multi-agent Driving a car Fully observable, deterministic, sequential, static, discrete, single-agent Partially observable, stochastic, sequential, dynamic, continuous, cooperative multi-agent Assembly-line inspection robot Fully observable, deterministic, episodic, dynamic, continuous, single-agent ECE457 Applied Artificial Intelligence R. Khoury (2007) Page 21