1. 1/34 Intelligent Agents Chapter 2 Modified by Vali Derhami

2. 2/34 Outline Agents and environments Rationality PEAS (Performance measure, Environment, Actuators, Sensors) Environment types Agent types

3. 3/34 Agents An agent is anything that can be viewed as perceiving its environment through sensors and acting upon that environment through actuators Human agent: eyes, ears, and other organs for sensors; hands,legs, mouth, and other body parts for actuators Robotic agent: cameras and infrared range finders for sensors;various motors for actuators General assumption: agent can perceive its own action

4. 4/34 Agents (cont.) Percept sequence is the complete history of everything the agent has ever perceived.

5. 5/34 Agents and environments Agent's behavior is described by the agent function that maps any given percept sequence to an action. تابع عامل یک شرح ریاضی انتزاع گونه است. در حالیکه برنامه عامل پیاده سازی کامل آن است که در داخل سیستم فیزیکی اجرا می شود. The agent function maps from percept histories to actions: [f: P*  A ]  Tabular representation: a large table for most agents The agent program runs on the physical architecture to produce f agent = architecture + program

6. 6/34 Vacuum-cleaner world Percepts: location and contents, e.g., [A,Dirty] Actions: Left, Right, Suck, NoOp

7. 7/34 A vacuum-cleaner agent

8. 8/34 Rational agents An agent should "do the right thing", based on what it can perceive and the actions it can perform. The right action is the one that will cause the agent to be most successful Performance measure: An objective criterion for success of an agent's behavior E.g., performance measure of a vacuum-cleaner agent could be amount of dirt cleaned up, amount of time taken, amount of electricity consumed, amount of noise generated, etc. Note: Design performance measures according to what one actually wants in the environment, rather than according to how one thinks the agent should behave.

9. 9/34 What is rational The performance measure that defines the criterion of success. The agent's prior knowledge of the environment. The actions that the agent can perform. The agent's percept sequence to date.

10. 10/34 Rational agents Rational Agent: For each possible percept sequence, a rational agent should select an action that is expected to maximize its performance measure, given the evidence provided by the percept sequence and whatever built-in knowledge the agent has.

11. 11/34 Omniscience, learning, and autonomy Rationality is distinct from omniscience (all-knowing with infinite knowledge) عقلانیت بیشینه میکند راندمانی که امید می رود در حالیکه کامل بودن (perfection) راندمان واقعی را بیشینه میکند. Agents can perform actions in order to modify future percepts so as to obtain useful information (information gathering, exploration) An agent is autonomous if its behavior is determined by its own experience (with ability to learn and adapt)

12. 12/34  Successful agents split the task of computing the agent function into three different periods:  During designing: some of the computation is done by its designers;  During deliberating (thinking) on its next action, the agent does more computation;  During learning from experience: it does even more computation to decide how to modify its behavior.

13. 13/34 Task Environment (PEAS) PEAS: Performance measure, Environment, Actuators, Sensors Consider, e.g., the task of designing an automated taxi driver: –Performance measure Environment –Actuators –Sensors

14. 14/34 PEAS Consider, e.g., the task of designing an automated taxi driver:

15. 15/34 PEAS Agent: Medical diagnosis system  Performance measure: Healthy patient, minimize costs, lawsuits  Environment: Patient, hospital, staff  Actuators: Screen display (questions, tests, diagnoses, treatments, referrals) Sensors: Keyboard (entry of symptoms, findings, patient's answers)

16. 16/34 PEAS Agent: Part-picking robot  Performance measure: Percentage of parts in correct bins  Environment: Conveyor belt with parts, bins  Actuators: Jointed arm and hand  Sensors: Camera, joint angle sensors

17. 17/34 PEAS Agent: Interactive English tutor  Performance measure: Maximize student's score on test  Environment: Set of students, testing agency  Actuators: Screen display (exercises, suggestions, corrections)  Sensors: Keyboard entry

18. 18/34 Environment types Fully observable (vs. partially observable): An agent's sensors give it access to the complete state of the environment at each point in time. Deterministic (vs. stochastic): The next state of the environment is completely determined by the current state and the action executed by the agent. (If the environment is deterministic except for the actions of other agents, then the environment is strategic) محیطی که کاملا مشاهده پذیر نباشد یا قطعی نباشد نایقین (uncertaion) گفته می شود Episodic (vs. sequential): The agent's experience is divided into atomic "episodes" (each episode consists of the agent perceiving and then performing a single action), and the choice of action in each episode depends only on the episode itself.

19. 19/34 Environment types Static (vs. dynamic): The environment is unchanged while an agent is deliberating. (The environment is semidynamic if the environment itself does not change with the passage of time but the agent's performance score does) Discrete (vs. continuous): A limited number of distinct, clearly defined percepts and actions. Single agent (vs. multiagent): An agent operating by itself in an environment.

20. 20/34 Environment types Chess with Chess without Taxi driving Image a clocka clock Analysis Fully observableYesYesNo Yes DeterministicStrategicStrategicNo Yes Episodic NoNoNo Yes Static SemiYes No Semi DiscreteYes YesNo No Single agentNoNoNo Yes The environment type largely determines the agent design The real world is (of course) partially observable, stochastic, sequential, dynamic, continuous, multi-agent

21. 21/34 Structure of Agents The job of AI: Design the agent program that implements the agent function mapping percepts to actions. Agent= Architecture +Program Program has to be appropriate for the architecture

22. 22/34 Agent functions and programs Agent programs: they take the current percept as input from the sensors and return an action to the actuators.  Difference between agent program and agent function: oAgent program: takes the current percept as input oAgent function: takes the entire percept history. Aim: find a way to implement the rational agent function concisely

23. 23/34 Table-lookup agent Drawbacks: Huge table Take a long time to build the table No autonomy Even with learning, need a long time to learn the table entries

24. 24/34 Agent program for a vacuum- cleaner agent \input{algorithms/reflex-vacuum-agent- algorithm}

25. 25/34 Agent types  Four basic types in order of increasing generality: Simple reflex agents Model-based reflex agents Goal-based agents Utility-based agents

26. 26/34 Simple reflex agents

27. 27/34 Vacuum agent

28. 28/34 Simple reflex agents

29. 29/34 Model-based reflex agents

30. 30/34 Model-based reflex agents

31. 31/34 Goal-based agents

32. 32/34 Utility-based agents

33. 33/34 Learning agents

34. 34/34 Learning agents  Four conceptual components Learning element: making improvements. Performance element: selecting external actions. Critic: tells the learning element how well the agent is doing with respect to a fixed performance standard Problem generator: suggesting actions that will lead to new and informative experiences.

35. 35/34 تمرین دوم از وب سایت برداشته شود.