Dominion

Rules

Divide the grid into some regions formed of adjacent squares, with using dominoes (1×2 black cells). Dominoes cannot overlap or touch each other by the sides. Each region must contain only the same letters and at least one letter. All the identical letters have to be in the same region.

(Rules and example from WPC 2016 IB)

History of the puzzle

Invented by Naoki Inaba (Japan) in 2010. First set of puzzles he created can be seen here.

Appearances in the past WPCs

• WPC 2019/World Cup Playoffs by Jürgen Blume-Nienhaus
• WPC 2016/Round 12 by Matúš Demiger
• WPC 2016/Round 15 (part of a Matchmaker puzzle) by Matej Uher