a partial sudoku puzzle
1 Attachment(s)
Hi MersenneForum,
I picked up a Sudoku book today and tried again at a puzzle that had stumped me before. I was able to put in the number 8 near the center and then I was again stumped. I know there are some advanced Sudoku techniques out there, on the internet. Can anyone tell me a next step ( with logic) for the attached puzzle? Also the possibility of a machine solver has been considered. This is from the "New York Post Bloom Sudoku Book" (fiendish puzzles c 2013). I am stuck on page 31. I do not want to 'reverse engineer' the puzzle by looking in the answer section. Regards, Matt 
Well, in the topright box you can fill in a 6 (in the bottommiddle position) because nothing else in the middle column can be a 6. Similarly the middle row across the top has only one position to put a 9, the middle of the left grid. That forces the "49" at the bottom to 4 and the "47" above it to 7, and probably cascades further.

[QUOTE=MattcAnderson;462278]Hi MersenneForum,
I picked up a Sudoku book today and tried again at a puzzle that had stumped me before. I was able to put in the number 8 near the center and then I was again stumped. I know there are some advanced Sudoku techniques out there, on the internet. Can anyone tell me a next step ( with logic) for the attached puzzle? Also the possibility of a machine solver has been considered. This is from the "New York Post Bloom Sudoku Book" (fiendish puzzles c 2013). I am stuck on page 31. I do not want to 'reverse engineer' the puzzle by looking in the answer section. Regards, Matt[/QUOTE] Lets rewrite it here, on the forum ( in roughly,original form), instead of the file and rotating it: [TEX] \begin{tabular}{ccccccccc} \hline &&6&&&&&9\\ \hline &&2&8&&6&&&1\\ \hline 8&1&&&5&&&&\\ \hline &5&&&2&&&&\\ \hline &&3&7&6&1&9&&\\ \hline &8&&&3&&&1&\\ \hline &&&&9&&&4&3\\ \hline &&&3&&7&6&&\\ \hline 2&&&&&&1&&\\ \hline \end{tabular}[/TEX] now it's mostly a combination of set union, and set difference to consider. 
[QUOTE=science_man_88;462313]...now it's mostly a combination of set union, and set difference to consider.[/QUOTE]
Indeed. This puzzle is trivial to solve. "2" is the only possible solution for 2x,5y. Everything simply cascades. 
thanks
Hi Mersenne Forum,
Thank you to all the responses to this thread. I see Greathouse's reasoning for a 6 in the bottom row of the top right 3 by 3 grid. Now this one should be easy. Regards, Matt 
All times are UTC. The time now is 15:02. 
Powered by vBulletin® Version 3.8.11
Copyright ©2000  2022, Jelsoft Enterprises Ltd.