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Advanced AI. Prof. Sarit Kraus Bar-Ilan University Slides adjusted from David Parkes from Harvard Univ. Different Goals of AI. sensors. percepts. ?. environment. agent. actions. actuators. An agent and its environment.
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Advanced AI Prof. Sarit Kraus Bar-Ilan University Slides adjusted from David Parkes from Harvard Univ. 89-950 Lecture 1
Different Goals of AI 89-950 Lecture 1
sensors percepts ? environment agent actions actuators An agent and its environment agent :Something that takes input (percepts) from its environment through sensors and takes actions upon its environment, using actuators. agent function: mapping from percept sequence to an action 89-950 Lecture 1
What is an Agent? PROPERTY MEANING • Situated Sense and act in dynamic/uncertain environments • Flexible Reactive (responds to changes in the environment) • Autonomous Exercises control over its own actions • Goal-oriented Purposeful • Persistent Continuously running process • Social Interacts with other agents/people • Learning Adaptive • Mobile Able to transport itself 89-950 Lecture 1
Examples • Medical diagnosis system • Foreign-language tutor • Web shopping program • Virtual humans for training, entertainment 89-950 Lecture 1
Examples of how the agent function can be implemented • Table-driven agent • Simple reflex agent • Reflex agent with internal state • Agent with explicit goals • Utility-based agent • Learning agent More sophisticated 89-950 Lecture 1
Consider a Taxi Driving Agent • Goal: correct destination, manage fuel consumption, minimize driving violations • Environment: roads, people, potholes, etc. • Actuators: gas pedal, breaks, etc. • Sensors: video camera, speed, etc. 89-950 Lecture 1
1. Table-driven agent An agent based on a pre-specified lookup table. It keeps track of percept sequence and just looks up the best action • Disadvantage: • Huge number of possible percepts • Takes long time to build the table • Not adaptive e.g. Taxi. |P|t states, for |P| percepts, and lifetime T T t=1 27 MB/sec, 1 hour, 10^150 entries (c.f. 10^80 atoms in observable universe) 89-950 Lecture 1
Simple Reflex Agent sensors What the world is like now Environment What action I should do now Condition - action rules actuators 2. Simple reflex agent Use a simple rule, and just the current percept, perform the action associated with that rule. table still too large, and current percept may not be enough, and no goal. 89-950 Lecture 1
3. Model-Based Reflex Agent sensors State How the world evolves What the world is like now What my actions do Environment What action I should do now Condition - action rules actuators maintain model of world to make-up for lack of percepts, table still too large, and still no goals. note flexible. 89-950 Lecture 1
sensors State How the world evolves What the world is like now What my actions do Environment What it will be like if I do action A What action I should do now Goals actuators 4. Model Based, Goal Based deliberative, goal-based, choosing actions with search and Planning. more flexible (not pre-specified). 89-950 Lecture 1
sensors State How the world evolves What the world is like now What my actions do What it will be like if I do action A Environment How happy I will be in such as a state Utility What action I should do now effectors 5. Utility-based agent refined measure of ``good’’ and ``bad’’, utility= happiness 89-950 Lecture 1
Properties of environments Observable vs. Partially-observable (complete state of world is available to agent) Deterministic vs. no-deterministic (Stochastic) (no uncertainty about effects of actions) Static vs. Dynamic (do not need to observe while deliberate) Discrete vs. Continuous (state/percepts/actions/time) Single vs. Multiagent (cooperative vs. competitive) 89-950 Lecture 1