Category Archives: SuDoKuGo

My busy busy nightmare generator

Size Matters

It has cost me a night sleep, but I have rewritten parts of SudokuGo, my batch generator. It now can generate any Sudoku with boxes of size 2×2, 2×3, 3×3 (duuh), 3×4 and 4×4, including the main variants, Jigsaw, X and DG.

If have also generalized the Windoku concept. A 4×4 sudoku can contain 1 extra 2×2 box in the center, with 3 implied extra groups. No Windows for the irregular formats, but 16×16 can have 9 extra 4×4 boxes, with 7 implied groups. I’m not sure this format will ever work, because the program chokes on generating a valid grid. Too bad if it turns out to be an impossible format, because it looks great. I’ve tested generation of the Windoku groups without box constraints, and that works. The combination may prove to be too much. Just to many conflicting constraints.

Also released SudoCue version 1.5.1. Redid the optimizer as many requested it should work, and also added a menu option to fetch the daily competition puzzle from www.sudoku.org.uk. Undo and redo work on candidates too.

I am now trying to implement Almost Locked Sets. Considering every possibility, the program now found 228 sets in a single grid. Needs some work to filter out the sets that are actually useful. I think I start sorting out the sets that do not overlap, but have a restricted common digit x. It must be possible to find ALS-xz patterns amongst these pairs of sets. I’ll write some more if I made some progress. Would be nice to be the first program that supports ALS, after being the first (and still the only) that supports finned fish.

The Clueless Days

Sometimes I feel clueless myself.

The first of these monster puzzles were meant as an experiment. People jumped on it and wanted more and more. Creating these puzzles manually involves some risk. You have a shot at it and when it can be solved by 10 instances of SudoCue, then it should be OK. Difficulty can only be determined by testing. Because that takes such a long time, I tend to approve anything that passes the test, no matter how difficult.

Now I have CluelessMaker. It accepts 9 template-generated puzzles and a solution as input, maps the 9 puzzles to the central solution, and solves the whole thing in a fraction of a second. It counts naked/hidden singles, line-box interactions and naked/hidden subsets. More techniques will be built into it, but I can manually assess an almost solved clueless to see what is needed to complete it. If it’s a fair technique, I’ll let it pass.

What worries me, is that players no longer fancy the ‘regular’ sudokus. They want more and more clueless specials. If have made 4 by hand, the rest will be machine made, and more reliable.

Also had some fun on the player’s forum with the superior and inferior threads.

Sudoku X

Almost forgot to blog this.

With my SodokuGo program, I can now also generate Sudoku-X puzzles. Posted a few on the NL forum, but not a lot of response. Interesting that you can easily generate 15 and 16 clue sudoku-X. I saw one with 13 clues on a website.

It would be cool to generate my Clueless Specials with SudokuGo.

New developments

Not revealing anything yet, but I have registered 4 domains and they’re beauties.

A new application is in the making. Sorry, it is not Sudoku related.

Also, worked on the Sudoku database. Another 10,000 have been added. I am now saving more indirect properties of the puzzles and it is possible to hunt for special combinations of properties. No freebees, tight solving path, breath in solving techniques, large number of eliminations between single steps.

We can now almost supply a Sudoku “made to order”. That would be the real killer in syndication.

A Quiet Saturday

Spent some time helping a guy insert the syndicated link to www.SudoCue.net. He finally got it built in and now he’s running a daily Sudoku from my database.

More! More!

Also did some research on the easies in my database. Created a program that does some low-end difficulty analysis. I’m not gonna spill all the beans here, but some of the considerations are:

  • How tight is the solving path? Are there multiple routes or just a single path that you need to follow?
  • How many singles can be placed before an elimination technique is called for?

Refinement in difficulty assessment will help me identify better nightmares.

My toughest Sudoku generated

This is the toughest Sudoku in stock, from my own manufacturing plant. Is it really a complicated one? It just depends on what force is applied against it. A few nice loops could break it… maybe.

 My toughest

  Tough is in the eye of the beholder. In this case, Sudo Cue.

Readers?

Was surprised to see how many people are reading my daily entries here. OK, needed to tidy it up a bit, and translated the most recent posts in English. Blogging is a dangerous activity. Before you know it, everybody is looking over your shoulder.

Finished the Scanning article in www.Sudopedia.org. May need some revisions, but at least it is a consistent story now. Still no cowriters.

I have isolated the 400.000 Sudokus in my Access database that can be classified as ‘easy’. I will run a special program today, that performs a solving speed test on these sudokus. This is something I found out recently. It is not only the requirement of solving techniques, but also the solving speed that determines the difficulty of a sudoku. For the lower grades, this is the most important benchmark. A whole series of sub-grades can be worked out.

But not for me. I have to keep up my reputation, so I will always supply sudokus that are a tad more difficult than the rest of them. This solving speed test will help me pick out the nice ones.