Planning in AI can be defined as a problem that needs decision making by intelligent systems to accomplish a given target.

A classical planning has the following assumptions about the task environment:

i. Fully observable: Agent can observe the current state of the environment.

ii. Deterministic: Agent can determine the consequences of its actions.

iii. Finite: There are finite set of actions which can be carried out by the agent at every state in order to achieve the goal.

iv. Static: Events are steady. External event which cannot be handled by agent is not considered.

v. Discrete: Events of the agent are distinct from starting step to the ending state in terms of time.