## Article - Advanced Method for Solving Sudoku

Advanced methods and approaches for solving Sudoku puzzles

### Article - Advanced Method for Solving Sudoku

Hi Everyone, I am about a year or more player of Sudoku which my girlfriend converted me from Word Searches to this and I hate her for I am an Sudoku Addict now. I have gone month or more not playing and then because of that re-developing the skills I developed/figured-out just from doing it and this occurs every now and then for I just need breaks from whatever. The point is I am back into the game.

I speed through beginner minutes per puzzle, medium it varies but takes a little longer than beginner but no where as long as hard level. Then there is hard level and my time varies.

The point of this post is I am looking for input on solving that isn't confusing/overwhelming so I did a Google search and found this article that I printed and started reading but as soon as I hit tip #1 "Sole Candidate" I see an issue with this.

https://www.kristanix.com/sudokuepic/sudoku-solving-techniques.php

They say
When a specific cell can only contain a single number, that number is a "sole candidate". This happens whenever all other numbers but the candidate number exists in either the current block, column or row. In this example, the red cell can only contain the number 5, as the other eight numbers have all been used in the related block, column and row.

But the fact is I don't agree that the #5 is obvious. While the #5 is the obvious missing number, it being in that red block is NOT the obvious choice. And because of this issue I have right off the bat with this article I am wondering if I am wasting my time on this article. For my method I would need other blocks filled or/and the #5 in other areas to truly say yes, the #5 should be in box....

Thoughts? And please try to be clear for I read a lot of Sudoku explanations that have me saying out-loud WHAT???
speedy

Posts: 3
Joined: 17 February 2015

### Re: Article - Advanced Method for Solving Sudoku

I think that you're confused by the fact that what is shown is not a complete puzzle, but just a set of numbers to illustrate the point being made. Given that set, the red cell can contain only a 5. There are not enough other clues (constraints) to make any other staments about this example, but just enough to describe what is often called, in fact, a naked single.

HTH

Mike Metcalf

m_b_metcalf
2017 Supporter

Posts: 9661
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Location: Berlin

### Re: Article - Advanced Method for Solving Sudoku

That article uses some non-standard terminology, but otherwise seems like as good a place to start as any.

For their "sole candidate" technique (which we call a naked single): what digit(s) can you put in the red cell? It isn't a question of where else you can put a 5. It is only a question of what you can put in the red cell. Eight of the nine possible digits are ruled out. 5 is the only digit that can go there without immediately creating a contradiction (i.e. breaking the Sudoku one rule).

JasonLion
2017 Supporter

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Joined: 25 October 2007
Location: Silver Spring, MD, USA

### Re: Article - Advanced Method for Solving Sudoku

Hi Everyone,
I printed out the article for whatever reason I prefer reading such things on paper versus a screen. As I looked at it closer I see how the #5 could have been determined but I have to say with my methods I would question if I would find it that fast but either way the example is actually correct. Lesson that I should re-read an article before assuming the worst.

The only method that seem to be something I don't do and I have heard/read about it elsewhere is the Swordfish method. I sort of get what they are saying, but going to look elsewhere for further examples of this method. Any suggestions or/and comments regarding that?
speedy

Posts: 3
Joined: 17 February 2015