Intelligent Agents

Software agentsO Monday:

O Overview video (Introduction to software agents)O Agents and environmentsO Rationality

O Wednesday:O PEAS (Performance measure, Environment, Actuators,

Sensors)O Example of simple and not-so-simple software agents

O Friday:O Environment typesO Agent typesO Group discussion

Very short software agents overview

O http://labcast.media.mit.edu/?p=23

O What is an agent?: A computer program that is O Embodied (i.e local)O Situated (ie. has knowledge of / responds to

its situation / environment)O Autonomous (i.e decides what action to take

based on its own situation)O Cooperating (i.e can communicate with other

agents to achieve tasks)

Agent and environments

Agent and environments

O Agents include humans, robots, softbots, thermostats, etc.

O The agent function maps from percept histories to actions:

f : P -> AO The agent program runs on the

physical architecture to produce f

Vacuum-cleaner world

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

O Actions: Left, Right, Suck, NoOp

A vacuum-cleaner agent

Pseudocode

What is the right function?Can it be implemented in a small agent program?

RationalityO Fixed performance measure evaluates the environment

sequenceO one point per square cleaned up in time T?O one point per clean square per time step, minus one per move?O penalize for > k dirty squares?

O A rational agent chooses whichever action maximizes the expected value of the performance measure given the percept sequence to date

O Rational is different from omniscientO percepts may not supply all relevant information

O Rational is different from clairvoyantO action outcomes may not be as expected

O Rational is different from successfulO Rational exploration, learning, autonomy

PEASO To design a rational agent, we must

specify the task environment.Example: consider, e.g., the task of designing an automated taxi:O Performance measure: O Environment:O Actuators: O Sensors:

Another exampleO Internet shopping agents:

O Performance measure??O Environment??O Actuators??O Sensors??

Environment types

O The environment type largely determines the agent design

O The real world is (of course) partially observable, stochastic, sequential, dynamic, continuous, multi-agent

Agent typesO Four basic types in order of

increasing generality:O Simple reflex agentsO Reflex agents with stateO Goal-based agentsO Utility-based agents

Simple reflex agents

Reflex agents with state

Goal-based agents

Utility-based agents

Learning agents

ExampleO Simple example

O Demonstration of software agent on Linux

O Complex example:O http

://web.media.mit.edu/~hugo/demos/commonsense-aria.html

SummaryO Agents interact with environments through actuators and

sensorsO The agent function describes what the agent does in all

circumstancesO The performance measure evaluates the environment

sequenceO A perfectly rational agent maximizes expected performanceO Agent programs implement (some) agent functionsO PEAS descriptions define task environmentsO Environments are categorized along several dimensions:O observable? deterministic? episodic? static? discrete? single-

agent?O Several basic agent architectures exist:

O Reflex, reflex with state, goal-based, utility-based