ai csc361: intelligent agents1 intelligent agents -1 csc361

AI CSC361: Intelligent Agents 1

Intelligent Agents -1

CSC361


Intelligent Agents

• What are Agents?

• Structure of an Agent.

• What to consider when designing an agent?

• Types of Agents


What is an Agent?

• An agent is anything that can be viewed as perceiving its environment through sensors and acting upon that environment through actuators.


What is an Agent?

• Examples: – Human agent: Sensors eyes, ears, and other

organs; Actuators hands, legs, mouth, and other body parts.

– Robotic agent: Sensors cameras and infrared range finders; Actuators various motors connected to arms.


What is an Agent?

• Percept: agents’ input at any instant of time.

• Percept Sequence: complete history of what the agent has perceived so far.

• Behavior: what action, when?

• Agent function: maps from percept sequences to actions. [f: P* A]….. determines agents’ behavior.


What is an Agent?

• Agent Program runs on the physical architecture to produce f

• agent = architecture + program

• Environment: Surroundings in which the agent has to operate.


Vacuum-Cleaner Agent

• Percepts: location and contents, e.g., [A,Dirty]

• Actions: Left, Right, Suck, NoOp


Vacuum-Cleaner Agent

• The agent can be implemented using a table. Or the agent function may be implemented in some other way.

• How to build the table? Table could be very long.


Is an Agent Good or Bad?

• How to judge an agents’ behavior? Note: We are not talking about intelligent agents … just agents.

• An agent should strive to "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.



Examples:• 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.

• What could be the performance agent for a human agent?



• Rational agent: If an agent performs actions which maximize its performance measure the agent is called rational agent. Rational agent is a good agent.

• Autonomous agent: An agent is autonomous if its behavior is determined by its own experience (with ability to learn and adapt). Autonomous agent is good agent.


What to consider when designing an agent?

• We must consider PEAS: Performance measure, Environment, Actuators, Sensors.

• Consider the task of designing an automated taxi driver:– Performance measure: Safe, fast, legal, comfortable

trip, maximize profits– Environment: Roads, traffic, pedestrians, customers– Actuators: Steering wheel, accelerator, brake, signal,

horn– Sensors: Cameras, sonar, speedometer, GPS, odometer,

engine sensors, keyboard



• Consider the task of designing a 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)



• Consider the task of designing a 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



• Consider the task of designing a Interactive English tutor.– Performance measure: Maximize student's

score on test– Environment: Set of students– Actuators: Screen display (exercises,

suggestions, corrections)– Sensors: Keyboard


How to implement an Agent?

• An agent is completely specified by the agent function mapping percept sequences to actions.

• action f (percept-sequence).

• Aim: find a way to implement the rational agent function concisely.



• Table-lookup agent: looks up the action entry corresponding to the current percept sequence.

• 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



• Agent function implemented as a program in a programming language.

• Advantage: – can implement the agent function concisely.


What are the different types of agents?

• Two basic types in order of increasing generality:– Simple reflex agents– Model-based reflex agents– etc.


Simple Reflex Agent


Model-based Reflex Agent

ai csc361: intelligent agents1 intelligent agents -1 csc361

Documents

performance agent

agent good

good agent

autonomous agent

rational agent

agent program

human agent

agent function