Classic Sudoku - Uniqueness
(Published on 1. July 2020, 17:52 by Phistomefel)
Since this trick is everything but easy to spot, here is a little tip that uses the following picture.
Assume there are no other 3s and 4s in the sudoku except the ones shown in the picture. Of course, other digits are given, which can appear in any number and position. Can this sudoku then be uniquely solvable?
Now for the puzzle:
The puzzle is also available online via f-puzzles. Have fun solving!
Solution code: 3rd and 5th row
Comments
on 21. August 2021, 18:47 by Phistomefel
Added tag "Online solving tool".
on 4. June 2021, 20:33 by jovi_al
Beautiful classic, Phistomefel! While I typically avoid using uniqueness when solving, I adore when puzzles are made to showcase it. Wonderful work!
on 17. September 2020, 14:10 by cdwg2000
Video problem solving from Bilibili website: https://b23.tv/VOR8vI
on 1. July 2020, 23:17 by emmettcito
I'm curious how were you able to prove that this puzzle has a unique solution when you were constructing this when the intended solving path is by uniqueness. I am also very impressed that you were able to turn a boring old classical sudoku into something very interesting
@emmettcitto: Thank you! Proving the uniqueness of the solution is indeed an issue, when you need it to solve the sudoku. To this end, I used Andrew Stuart's Solver which was very helpful.
on 1. July 2020, 21:05 by Phistomefel
@Dandelo: Ich denke nicht, dass es sich bei meinem Trick um ein Unique Rectangle handelt. Der verlinkte Artikel in der SudokuWiki behandelt ein anderes Thema, auch wenn es erst einmal relativ ähnlich wirkt. Außerdem würde es mich doch sehr wundern, falls es sich bei meinem Trick doch um Unique Rectangles handelt, der Sudoku Solver von der SudokuWiki den Trick aber nicht erkennt.
on 1. July 2020, 20:47 by Dandelo
Auf https://www.sudokuwiki.org/Unique_Rectangles findet man einen ausführlichen Artikel über diesen Trick.
on 1. July 2020, 20:40 by Phistomefel
@MavericksJD: Thank you! I'm glad you enjoyed it.
on 1. July 2020, 20:21 by MavericksJD
Amazing one @Phistomefel. Only when I was stuck in box 7&8, did I see the trick.
Enjoyed it.
