# Search Terminology

**Problem Space**: It is the environment in which the search takes place. (A set of states and set of operators to change those states)
**Problem Instance**: It is Initial state + Goal state
**Problem Space Graph**: It represents problem state. States are shown by nodes and operators are shown by edges.
**Depth of a problem**: Length of a shortest path or shortest sequence of operators from Initial State to goal state.
**Space Complexity**: The maximum number of nodes that are stored in memory.
**Time Complexity**: The maximum number of nodes that are created.
**Admissibility**: A property of an algorithm to always find an optimal solution.
**Branching Factor**: The average number of child nodes in the problem space graph.
**Depth**: Length of the shortest path from initial state to goal state.