Nature of Environment

Environments in which agents operate can be defined in different ways. It is helpful to

view the following definitions as referring to the way the environment appears from the

point of view of the agent itself.

 Observability

In terms of observability, an environment can be characterized as fully observable or

partially observable.

In a fully observable environment all of the environment relevant to the action being

considered is observable. In such environments, the agent does not need to keep track of

the changes in the environment. A chess playing system is an example of a system that

operates in a fully observable environment.

In a partially observable environment, the relevant features of the environment are only

partially observable. A bridge playing program is an example of a system operating in a

partially observable environment.

 Determinism

In deterministic environments, the next state of the environment is completely described by the current state and the agent’s action. Image analysis If an element of interference or uncertainty occurs then the environment is stochastic. Note that a deterministic yet partially observable environment will appear to be stochastic to the agent. If the environment state is wholly determined by the preceding state and the actions of multiple agents, then the environment is said to be strategic. Example: Chess

 Episodicity

 An episodic environment means that subsequent episodes do not depend on what actions

occurred in previous episodes.

In a sequential environment, the agent engages in a series of connected episodes.

 Dynamism

Static Environment: does not change from one state to the next while the agent is

considering its course of action. The only changes to the environment are those caused by

the agent itself.

 • A static environment does not change while the agent is thinking.

• The passage of time as an agent deliberates is irrelevant.

• The agent doesn’t need to observe the world during deliberation.

 A Dynamic Environment changes over time independent of the actions of the agent -- and

thus if an agent does not respond in a timely manner, this counts as a choice to do nothing

 Continuity

If the number of distinct percepts and actions is limited, the environment is discrete,

otherwise it is continuous.agents.