One of the grid segments (called the ``blank'') is empty. A tile can be moved into the blank position from a position adjacent to it, thus creating a blank in the tile's original position.
The goal is to move from a given initial position to the final position in a minimum number of moves.
Discrete Optimization: Example
An 8-puzzle problem instance: (a) initial configuration; (b) final configuration; and (c) a sequence of moves leading from the initial to the final configuration.
