Intelligent Agents
Chapter 2

• Agents and environments
• Rationality
• PEAS (Performance measure,
Environment, Actuators, Sensors)
• Environment types
• Agent types

• 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

Agents and environments

• The agent function maps from percept histories
to actions:
[f: P*  A]
• The agent program runs on the physical
architecture to produce f
• agent = architecture + program

Vacuum-cleaner world

• Percepts: location and contents, e.g.,
• Actions: Left, Right, Suck, NoOp

A vacuum-cleaner agent
• \input{tables/vacuum-agent-function-table}

Rational 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
• 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.

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

Rational agents
• Rationality is distinct from omniscience
(all-knowing with infinite knowledge)
• Agents can perform actions in order to
modify future percepts so as to obtain
useful information (information gathering,
• An agent is...