The New Sudoku Players' Forum

[ram_einstein]

What is the criterion for a Sudoku puzzle being solvable? The number of inital values provided? Or is every Sudoku puzzle solvable?

[ctettam9]

I think what you are refering to is whether a game is solvable or not....There must be a minimum amount of starting numbers (which is 17). Now I am refering to "unique" solutions. If a puzzle has more than one solution, then it is not a "valid" sudoku.

Here is a website that concentrates on unique solutions with the minimum number of hints (17).

http://www.csse.uwa.edu.au/~gordon/sudokupat.php

If you are wondering if a puzzle is solvable, just grab one of the many computer sudoku games that are floating around and punch in your starting values. Most of them will tell you if the puzzle is valid (only one solution AND can be figured out by logic) AND if it is solvable!!!

Chris

[lunababy_moonchild]

Try this : Conditions for sudokus (Click on the blue writing).

Aesthetically, they should (but it is by no means compulsory, it really depends on your personal taste) be : symmetrical, elegant and have only one solution which does not require guessing.

As I said it really depends on your personal taste. There are those who enjoy guessing, still those who enjoy finding all of the solutions to a multiple solution puzzle and those - I feel sure - who don't really care if the puzzle is symmetrical or elegant. There are really no hard and fast rules to it.

Personally, I feel lucky to have found this puzzle in the days when the only puzzles available were : Wayne Gould's software, the Times Book One (Wayne Gould's) and either puzzles appearing in The Times (Wayne Gould's) or the Daily Mail (not Wayne Gould's). In many ways it was a lot easier, especially when I was learning. The choice array just now would stagger even the most experienced puzzler.

That said, I can state confidently that Wayne Gould's - Pappocom - puzzles can be relied upon to be symmetrical, elegant and contain only one solution which does not require guessing. They are computer generated. Nikoli's puzzles - also available through Puzzler Media - are hand-crafted and can also be relied upon to be symmetrical, elegant and contain only one solution which does not require guessing. Nikoli are the Japanese company who introduced the puzzle to Japan and who have been hand-creating said puzzle for the Japanese public for over 20 years.

I should say that there is a slight difference between hand-crafted and computer-generated (the subject of much debate) and again, it depends on personal preference. Just in case you need to know, I do both.

I do hope that provides some help

Luna