Puzzle cannot be solved logically.

[treemana]

Has anyone else had a problem entering puzzles from a book or newspaper and get the "This puzzle cannot be solved logically" message?

This has happened to me several times. (I'm sure I entered the puzzles correctly.) It only happens on difficult ("tough", "5-star", etc.) puzzles.

I have been able to enter and solve the puzzles using a different Sudoku program. (Using forcing-chains and nishio methods.)

I purchased the Astraware Sudoku program because I liked it the best. (Best board-layout and data entry.) But now I find myself using a competing product for the difficult puzzles.

Did I choose wrong?

Any help/suggestions would be appreciated. I am currently using version 1.20 for the Palm OS.

Thanks.

[Howard]

Many newspapers and books don't distinguish between puzzles that can be solved using logical methods, and those that need to be solved by trial-and-error. They often rate the difficulty on how many seed clues are given, rather than any real measure of how difficult it is to solve.

Our Sudoku doesn't (currently) solve by the Nishio method (which is quite close to the trial and error method), nor several of the later techniques (such as tabling and colouring).

It *is* possible to still solve the puzzle (providing it is a valid puzzle with a unique solution) by a "brute force" method of trial and error with recursion, but a problem there would be that it wouldn't be able to give you hints as you go along, so it wasn't a priority for the early releases.

Upcoming updates are more to do with usability, improving menus, and better gameplay functions, although I am intending to add in some more of the solving techniques later in the year.

I appreciate you choosing Astraware Sudoku for its layout and entry features - that's where we concentrated for the first release. I hope that we'll also add some more of the higher level functions (which perhaps are beyond average players needs!) later on.

Howard

[treemana]

Thanks for the prompt reply. I look forward to your future releases.

[NeilB]

I still find Astraware Sudoku to be a very good solver. I've compared certain puzzles to some PC-based solvers (Simple Sudoku and Sudoku Cue) and online solvers (http://www.scanraid.com/sudoku.htm) and Astraware comes out on top.

Yet, I still would appreciate if you would build in some more solving strategies-- coloring and the 'uniqueness test' are two that I would like to see. The Uniqueness Test is easier for humans to see than it would be to program (perhaps). But I find cases where canidates can be eliminated using the uniqueness test all the time.