We present a variant of Sudoku called Sudoku Ripeto. It seems to be the first to admit any combination of repeated symbols, and includes Sudoku as a proper subset. We present other Sudoku Ripeto families, each with a different repetition pattern. We define Sudoku Ripeto squares and puzzles, prove several solving rules that generalize those for Sudoku, and give sufficient conditions to flexibly solve puzzles with rules only, without search.
Apt, K.R. (2003). Principles of Constraint Programming. Cambridge: Cambridge University Press.
2.
Arnab, K.M., Sunanda, J., Sudipta, R. & Rajat, K.P. (2014). An exhaustive study on different sudoku solving techniques. IJCSI International Journal of Computer Science Issues, 11(2), 247–253.
3.
Arroyo, F. (2016). Técnicas Avanzadas del Sudoku. Santa Eulalia. Asturias: Chessy.
4.
Felgenhauer, B. & Jarvis, F. (2020). Enumerating Possible Sudoku Grids. Available at: http://www.afjarvis.staff.shef.ac.uk/sudoku/sudoku.pdf (2020/01/09).
5.
Garns, H. (1979). Number place. Dell Pencil Puzzles and Word Games, 16(6).
6.
Laywine, C.F. & Mullen, G.L. (1998). Discrete Mathematics Using Latin Squares. New York: John Wiley and Sons.
7.
Mackey, W. (2007). Repeat-Letter Sudoku (Mensa Series). New York: Sterling Publishing Company.
8.
McGuire, G., Tugemann, B. & Civario, G. (2014). There is no 16-clue Sudoku: Solving the Sudoku minimum number of clues problem via hitting set enumeration. Experimental Mathematics, 23(2), 190–217. doi:10.1080/10586458.2013.870056.
