Tetromino Division

Dissection puzzles where the only rule is to dissect the grid into tetrominoes can also called be "Tetromino Division".

Rules

Divide the grid into tetrominoes. Each tetromino must contain exactly one clue. The clues represent the number of different shapes (under rotation and reflection) that share an edge with tetrominoes that contain the clue.

(Example from WPC 2015 IB)

History of the puzzle

Invented by Kazunori Saitoh (Japan) in 2001. First appeared as a submission to Internet Gekisakujuku, a contest where the best new puzzle type was decided from types submitted by readers of Puzzler magazine.

Appearances in the WPC

• WPC 2015/Round 10 by Kazunori Saitoh