The problem instance involves a grid of floor tiles and a single robot tasked with painting these tiles. The grid is a 4x3 layout, with rows labeled 0 to 3 and columns labeled 1 to 3. The tiles are labeled from tile_0-1 (top left corner) to tile_3-3 (bottom right corner). There is one robot, robot1, which can hold one color of paint at a time. The available paint colors are white and black.

- Robot Position and Paint:
  - Robot1 starts on tile_2-1 and is currently holding the color white.

- Available Colors:
  - Both white and black are available for the robot to switch to if needed.

- Tiles with Clear Status:
  - All tiles in the grid are clear except for tile_2-1, which is occupied by robot1. Therefore, the following tiles are clear:
    - Row 0: tile_0-1, tile_0-2, tile_0-3
    - Row 1: tile_1-1, tile_1-2, tile_1-3
    - Row 2: tile_2-2, tile_2-3
    - Row 3: tile_3-1, tile_3-2, tile_3-3

- Adjacency:
  - Vertical Adjacency:
    - Each tile has a tile directly above and below it, provided it exists within the grid. For example, tile_1-1 is directly above tile_2-1, and tile_0-1 is directly above tile_1-1.
  - Horizontal Adjacency:
    - Each tile has a tile directly to its left and right within the same row, provided it exists within the grid. For example, tile_0-2 is directly to the right of tile_0-1, and tile_0-1 is directly to the left of tile_0-2.

The robot can move to adjacent tiles and paint tiles directly below its current position, following the constraints and rules defined in the domain.