About

My actual name is John Welch. I live in Akron, Ohio.

My blog is about humanly practical techniques for solving Sudoku puzzles.

The purpose of the first year was to develop material for a workbook, to be called Systematic Sudoku. That evolved into the current blog, in which I am linking back to advanced and extreme techniques, as I review new collections of tough puzzles and tackle well-known monsters.

The current posts freely use terms defined much earlier, so new readers really need to start with home pages and early posts.  The beginners page and early  posts are very useful for those new to Sudoku solving.  More experienced new readers will gain quick insight into the blog from the Order of Battle page.  Even advanced new readers will need to scan through earlier posts to pick up procedures and jargon for reading current posts.  This is because of the many variations in Sudoku terminology and solving systems. Serious readers will need the reference pages on Sysudoku Speak and The Sysudoku Traces.

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24 Responses to About

  1. Natalie / Sophie says:

    hi we looked up your website as soon as we heard about it (we’re your naybors) we thought it looked cool and that you designed it very nicely

    • Sudent says:

      Natalie and Sophie, thanks for your generous comment. I know you are learning about good writing as a way to communicate your ideas, and I will not be surprised to be reading your blogs before long.

  2. Ali says:

    yes, yes, yes…NEVER GIVE UP!!! Congrats on finding life lessons through your game…I’ve never been able to do Sudoko…just not enough brain power I guess, lol.

    • Sudent says:

      Thanks, Ali. Believe me, it would be fascinating to discover how far you can go. It has been that way for me. All you need is a proper beginning. And its here.

  3. Arlinda says:

    i will be sharing this content with my friends for sure.

  4. Qingjun Lu says:

    Excellent work and have a lot of fun

  5. I truly enjoy examining on this internet site , it holds superb posts . “Dream no small dreams. They have no power to stir the souls of men.” by Victor Hugo.

  6. Agen IBCbet says:

    I do trust all the ideas you’ve presented to your post. They’re really convincing and can certainly work. Still, the posts are too brief for beginners. May just you please lengthen them a bit from next time? Thanks for the post.

    • Sudent says:

      Sorry, Lessley. I cannot make the current posts self contained. I think that is what you really want. I try to limit posts to one significant, but advanced idea. To make use of them, you must scan the pages and start with beginning posts and work forward. But don’t despair. It’s more interesting back there, because the earliest stuff applies to all Sudoku puzzles.

  7. richardgoodrich says:

    I have enjoyed your systematic sudoku more than any other. I am long over due saying so! I just bought Denis Berthier’s “The Hidden Logic of Sudoku” and have been trying to write a Visual Studio 2008 C# program that combines some of his ideas and yours. The biggest breakthrough for me has been your “slink” marking. I am trying to build a user interface that would allow a place to mark block slinks, row slinks, and column slinks with the “pencil marks” in the center. I got distracted by Wen Pei’s book of solving Sudoku in visual basic. I was in the process of converting his code to C#, when “work” raised its ugly head and demanded most of my time back. I have some different ideas on trace and have developed some of my own ideas – but not as complete as yours! I am an electronics engineer in a small company and a “hack programmer” My wife is concerned with my new addiction – actually a restored addiction at a much higher level then before! Sadly, it seems sudopedia.org has disappeared, so finally decided I should respond and thank your for your site. We aren’t getting any younger!

    Richard Goodrich

    • Sudent says:

      Richard, you made my day! Comments that reveal comprehension of my work are rare. I will respond to your trace comment as time allows, perhaps acknowledging it in a post.

      Before the blog, I wrote out about 2000 lines of Java code on basic solving, but abandoned the project when I realized that my programs data resources had already far exceeded ordinary human capabilities. You can appreciate how this pulled me back into visual aids and theoretical explanations of the “human engineered” theme. I want to follow your successes in dealing with Berthier’s “resolution methods”. My own encounters are reflected in “Berthier’s xyt-chains” of 12/27/11, “Casting for Regular Fish” of 4/3/12 and Berthier’s ‘useless’ claim in “XY Loops” of 3/16/12.

  8. high pr list says:

    Hey there! I was curious to know if setting up a blogging site such your own is tough to do for inexperienced people? I have been wanting to create my own blog for a while now but have been turned off because I’ve always believed it demanded tons of work. What do you think? Bless you

    • Sudent says:

      Look up WordPress. They offer domain management, data space, and an interface that makes blogging easy. The hardest part is deciding what options you need. I started out simple, and remain that way. Dumb and happy.

  9. Maija Ingelin says:

    I am a great friend of Krazydad Insane sudokus. Still, I´m no strategist. Would like to learn to master some strategies if they could lessen my futile work. (But I have been lazy to learn them).

    Would have one question, to begin with:.
    Krazydad informs that their Insane sudokus can´t be solved without at least one guess.
    My experience is that that is true.
    Question:
    If my first guess is a ´stupid guess´, (i.e.a haphazard guess), is it so that solution necessarily requires many many new guesses,.
    But if my first guess is a ´good guess´, does it lead to the solution quicklier, with fewer guesses.
    Have you an opinion if this?
    Yours faithfully, Maija a macska

    (or maybe no further guesses at all). I have experience of both.

    • Sudent says:

      Thanks, Maija, for reading and for your question. By “haphazard”, I take it you mean without a logical reason. I agree with you that such a guess is stupid. Even if it leads to a solution, that solution is all you have gained, and that was there all along, in the back of the book. So what is a good guess? I call it a trial. A trial is a timely and intelligent guess. It is anything but haphazard. It is assembled logically, and will gain information for further solving regardless of its outcome.

      Trials are not “trial-and error”. The “error” in trial-and-error” is making a guess which, if it fails, tells you nothing.

      Trials are to be made when no further direct logical inferences can be made. That way, the trial outcome cannot obscure logical contradictions in the puzzle that you might have discovered. As you learn more, you might go back to puzzles solved by trial, and attempt to bypass them.

      Finally, yes. Trials take bigger steps and come in much shorter sequences. Computers do back tracking well but humans don’t. The posts of the Insane review are a good introduction to trials. They show conclusively that many Insanes can be solved by direct logical inference without trials, and certainly without haphazard guesses.

      • Maija Ingelin says:

        Thank you very much for your valuable answer to my question. Very good indeed.

        I now literally understand what a Trial is.
        Krazydad´s 9×9 Insanes, so the producer says, CANNOT be solved without at least one guess, that is: one trial. In my experience, that is true.
        (Valuable information right at the start, because it tells you it´s no use trying to solve them by mire direct logical inference. Saves futile work.)

        You mentioned ´posts of the Insane review´, which are ´a good introduction to trials´ .
        I didn´t understand what that meant. Is it perhaps a book that you can buy?
        On the other hand I no longer really need such a helpful book. My own solutions teach me all the time, and it´s real fine to see.

        Happy sudoku future, Maija a macska

      • Sudent says:

        Hi Maija,

        “Posts of the Insane review” are the posts of this blog that cover the solving of the 10 Insane puzzles selected for the review. If you give up Sudoku books, I hope you will continue reading Systematic Sudoku. If I get a book out, it will be to present the lessons of the blog more clearly and efficiently than is possible in a blog.

        Sudent

  10. Maija-S. Ingelin says:

    Hello John,
    I have written you earlier as I am a great friend of Krazydad´s Insane Sudokus.
    Got good answers from you, thank you.
    Would have one more question. I hope I can formulate the question understandably enough.

    Have noticed long ago that when I make so called guesses (or trials), their number varies greatly.
    Sometimes this depends on my own lack of ability, but sometimes it depends on the sudoku (some of them are easier, some are harder)
    My question is: Take one particular insane sudoku. Is there A DEFINITE MINIMUM NUMBER of trials which are needed?
    Supposing that minimum number is four, and I need, say, nine.. That then means my five extra trials arise from my own mistakes, and the problem is to find the minimum number, four.
    And it is useless to try to solve the sudoku with LESS THAN FOUR trials.

    Kind regards, Maija a macska.

    • Maija-S. Ingelin says:

      “Awaiting moderation”? Was there something wrong with my comment, or what does “awaiting moderation” mean?

      • Sudent says:

        Hi Maija,

        “Waiting moderations” is a message that you are on the blog’s approved list, and that I am notified by email that your message needs attention. Congratulations! All messages to WordPress are reviewed by the blog moderator (me, in this case) before being published.

    • Sudent says:

      Maija, that’s a pretty deep question you have. I’m not a puzzle composer, but I can tell you there is no minimum number of trials, because there are so many possible trials and it is impossible to anticipate them. The harder the puzzle, the longer the trials and the more chance that they will be indecisive. This is because the puzzle has more “almost” solutions. Its more slippery. I strive for fewer trials by making each trial involve many candidates. Also, I use trials when there is no foothold for logical discoveries. Thanks for your question.

    • Maija-S. Ingelin says:

      Thanks very much for your reply regarding minimum number.of trials required.
      The main point in your answer is that THERE IS NO MINIMUM NUMBER. That is precisely what I wanted to know. It makes a great difference if I know that no minimum number exists. Maija a macska

  11. Hello John. I love your book “Mensa’s Guide to Solving Sudoku” by Peter Gordon. It is through this website I know your real name. Based on the strategies in your book, I recently published a book “CREATE CLASSIC SUDOKU: Make Your Own in Minutes” on Amazon.com.
    http://www.amazon.com/gp/product/0996204202?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

    I really appreciate of your “Mensa’s Guide to Solving Sudoku”, which guides me writing a computer software program to generate Sudoku puzzles in minutes and later ideas to handcraft your own Sudoku puzzles. Please let me know whether you are interested to have copies of my book. I would love to give you 1-3 free copies if you want to. My email address is hello@createclassicsudoku.com

    Wish you a great long weekend!

    Most respectfully,
    Yaling

    • Sudent says:

      Yaling,

      How could you get it so wrong? Elsewhere on my blog, you will find that I reviewed Peter Gordon’s Mensa Guide, and not favorably. If your book were based on strategies of my blog, I would be interested in your book, but if it is based on the Mensa Guide, please don’t send me a copy.

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