A very hard sudoku puzzle please try it

NewUrbanBlues · Posted: Mon May 25, 2009 4:55 pm Post subject: Solver Logic

Hello strmckr

I agree with you. Logic should solved any boards...

Can you elaborate more about this technique ? What is its name ? Is there some Web pages explaining the logic behind ?

Thanks

Thierry

lkSudoku · Posted: Mon May 25, 2009 6:28 pm Post subject:

In mathematical terms, there should exist a logic that solves all SuDoKu boards without backtracking, however this is only in theoretical term

All known logical methods that do not require backtracking are likely to cover only part of the entire logical space and thus when applying only known logical methods that are not equivalent to backtracking, it is not certain that they do solve any puzzle

strmckr · Posted: Tue May 26, 2009 2:50 am Post subject:

http://sudokuone.com/

Set Theory:

the logic behind takes alot of understanding matrics.

and there specific arangment limits.

there isnt any simplistic way to explain how it works.

are you familar with the sk loop? (first seen to solve easter monster)

if you are it is a prime example of a cover matrics limit.

16 cells with 4 digits
each so that all digits are covered exactly 4 times thus all intersections between the 16 cells cannot contain the 4 digits.

lkSudoku · Posted: Thu May 28, 2009 7:06 pm Post subject:

Perhaps another question should be asked:

Suppose we have any sudoku grid of size NxN where N is not a constant, can the solution be computed in time polynomial in N?

Is the NxN sudoku puzzle an NP-Hard problem?

Or, in simpler terms, can any NxN sudoku puzzle be solved in time that is not exponential in N?

A polynomial time algorithm rules out the set cover method, the trial and error method, and probably some other methods

gsf · Posted: Thu May 28, 2009 8:28 pm Post subject: