... by: Irish_guitar, Maryland USA

I find your site to be the most fabulous Sudoko site on the internet. Congratulations on a terrific site

... by: phil rock, new york

this is a wonderful website. what an effort!! superb learning tool for me. i've been looking a long time for a site like this. gave up sudoku for a while out of frustration and then found this. with a good puzzle book - it is a lot of fun.

thanks so much,

phil

... by: Mike Parker, Germany

Fantastic solver, but is it possible to put a breakpoint on a particular technique (i.e., ask the solver to run to the first/next instance of a particular solving technique, if any)? This would be great for those people wanting to train a specific technique, without having to painstakingly single step through the puzzle (only to find that the technique is not used in that puzzle anyway!).
If it's not possible right now, is such a feature on the "to do" list for the future?

... by: Scott B, Salt Lake City, Utah

Just wanted to say thank you for this website, truly amazing!!

... by: Mogulmeister, UK

Load Sudoku: 6.2.5.........4.32.....2...43..28....1....2........7..5..27...........81...68..27

Andrew,

The above 23 square sudoku does have one solution but seems impervious to all attacks - including your great solver. Any other strategies possible ? This is probably the toughest one I have ever encountered.
Andrew Stuart writes (16-Feb-2007):
Hi Mogulmeister, yes a very interesting sudoku. There is still a great deal to learn from these types of sudokus. The ones, such as these, that cant be solved by my solver has a certain characteristic - very few bi-value cells. Most cells in this, after all the strategies have been used, contain three or more possibles. Being able to descern a logical deduction with so many candidates left is the front line at the moment. Thanks for sharing it.

... by: Ruth, Gaithersburg, MD

Why are the same puzzles coming up each time I log onto your website? How can I get a different puzzle in the "Easiest", or Gentle, etc.?
Andrew Stuart writes (11-Feb-2007):
These are demonstration puzzles only. Examples to show the workings of the solver. Up to you to enter a puzzle you are stuck on. If you'd like to see a daily puzzle I do then have a look at http://www.sudoku.org.uk/daily.asp

... by: Richard Proctor, Utah

I've been watching for the book "Logic of Sudoku." Is there an update for it's release?

Andrew Stuart writes (6-Feb-2007):
Yes, today I have completed a pre-ordering form and payment system, please have a look at AT THIS PAGE. Within two weeks we'll do a special mailing to everyone whos been so patient, submitted their address and so on, and they'll get it before it hits amazon and the book distributors. Cover looks great!

... by: Tom, Manchester

Load Sudoku: 351926487..74...5.46.7.5...6..598.3.5...7...2...642........9....4...791...6254378

Hi Andrew, really like your site! It's been really useful as an instructional tool for learning the more advanced techniques. If I get completely stuck on a sudoku then I'll put it in and see what I've missed. When the solver finds the next move I'll then take a step back, switch that technique of and see if anything else works.

One thing I'd like to ask is how you choose the order of the techniques in the solver? Is it based on the difficulty of the technique? How often it occurs?

I might have a new technique for you too but I'm not sure. It's one I always use and I'd kinda assumed everyone else does to. I only really thought about this after doing Weekly Extreme No 18 from sudoku.org.uk. Once I'd moved to candidate elimination one use of the technique solved the puzzle. I'm going to wait until the weekly competition is over then post something about it on one of the forums.

I've put in the sudoku with all the numbers i'd found before having to move to candidate elimination.

Just a note on this, it wasn't particularly hard to get to this stage but the solver seems to really struggle and has to use 2 URs, an APE and a Forcing Chain to get close to this stage. I don't know if there's something missing from the solver or if this is a problem inherent in solving by candidate elimation. Any thoughts on this?

... by: SF, USA

I learned something new about Sudoku strategies. Your site is extremely informative and easy to use. Prior to checking your site, I spent several days trying to solve a puzzle that required some of the advanced strategies described on your site. I simply never knew the strategies were possible. Thank you.
Andrew Stuart writes (24-Jan-2007):
Thanks SF, always a pleasure!

... by: Dolores, Chicago

Thank you for the jigsaw solver.

On today's jigsaw puzzle the Law of Leftovers came up twice. I hope you have some time to show an explanation.

Also, I have been having a problem when changing canditates. I use Safari. Sometimes when I am clicking, it shuts down the browser or takes me to another place ( Sudoku solver).
Andrew Stuart writes (24-Jan-2007):
Hi Delores, I also use Safari/Firefox. I'll check it again but that's very od behaviour. It used to do something similar when I had the Flash look advert, but I changed it to an HTML one within an hour, and that was months ago.

... by: Ron, Thornhill On Canada

I could not find todays's (jan 20) entitled Legoman in your table of shapes
Andrew Stuart writes (24-Jan-2007):
I've no idea why, but in my Jigsaw Solver it's called 'Cyndie'