The New Sudoku Players' Forum

[denis_berthier]

KAKURO REFERENCES

The purpose of this thread is to define a set of references for Kakuro.

This first post will describe the general classification principles.
The second will be used to maintain the set of references.
The third and fourth are reserved for no precise reason but for anything of potentially general interest wrt to this thread.
The next ones will be used for proposing new references and for discussions.

General classification principles

I propose the following classification (which may also be discussed):

books (resolution rules, rating)
books (puzzle generation)
books (puzzles) (this may be too hard to keep up to date)
books (other, including non-player-oriented resolution)

published articles (resolution rules, rating)
published articles (puzzle generation)
published articles (other, including non-player-oriented resolution)

websites (discussions, forums)
websites (resolution rules, rating)
websites (online resolution)
websites (puzzles - whether they are generated online or extracted from a database or available in pdf format ...)

software (resolution rules, rating)
software (puzzle generation)
software (other, including non-player-oriented resolution)

A reference can appear under several headings (e.g. "website/resolution rules" and "website/puzzles", although in this example it would be better, if possible, to have two different URLs for two different sub-websites).
A few words may accompany a reference, for the sole purpose of better stating its content. Longer comments or discussions about a reference are better placed in separate posts (and a pointer to these can then be added to the reference listed in the second post below).

The interest of this thread will depend mainly upon the proposals for addition.
I created this thread but I don't consider I'm the ultimate judge of the relevance of a submitted reference. I'll add any proposed reference to the list, provided that:
- it is complete (author, title, publisher, date and ISBN for books; full journal details for articles, preferably with online access references; reachable webpage for websites),
- it is related to Kakuro.

[denis_berthier]

KAKURO REFERENCES

(this is currently only a starting point for this list - it doesn't even contain all the references I already know)


books (resolution rules, rating)

- Denis Berthier: "Pattern-Based Constraint Satisfaction and Logic Puzzles", Lulu.com, Nov. 2012, ISBN 978-1-291-20339-4.
(in the general framework defined in the book, chapter 15, pp. 399-426, is dedicated to Kakuro)
- Denis Berthier: "Pattern-Based Constraint Satisfaction and Logic Puzzles - second edition", Lulu.com, July 2015, ISBN 978-1-326-35064-2.
(in the general framework defined in the book, chapter 15, pp. 401-444, is dedicated to Kakuro)
The second edition has new examples of Kakuro puzzle solutions. It has detailed examples of g-whips (lacking in the first edition, although the theory of g-whips were already fully developed). Kakuro is the best example to show the power of the g-whip pattern.



books (puzzle generation)



books (puzzles)
(this may be too hard to keep up to date)



books (other, including non-player-oriented resolution)



published articles (resolution rules, rating)



published articles (puzzle generation)



published articles (other, including non-player-oriented resolution)



websites (discussions, forums)



websites (resolution rules, rating)

- http://www.brainbashers.com/kakurohelp.asp#w1
- http://www.conceptispuzzles.com/index.aspx?uri=puzzle/kakuro/tutorial
- http://www.wikihow.com/Solve-Kakuro



websites (online resolution)

- http://www.atksolutions.com/flashgames.html
(many different games, including Kakuro puzzles of varied sizes and difficulty)

- http://www.kakuroconquest.com

- http://www.kakuro-online.com

- https://www.kakurogame.com



websites (puzzles - whether they are generated online or extracted from a database or available in pdf format ...).
See detailed evaluations by Smythe Dakota in the next posts.

- http://www.atksolutions.com/flashgames.html
(many different games, including Kakuro puzzles of varied sizes and difficulty, some among the hardest to be found on the web)

- http://www.sudoku.org.uk/kakuroflash/kakuro.html
(the Kakuro part of Mepham's website)

- http://krazydad.com/kakuro/
(many Kakuro puzzles of varied sizes and difficulty, grouped in "books" of 8 puzzles in pdf format)

- http://www.kakuroconquest.com

- http://kakuro.binaryworlds.com/hard.php

- http://www.nikoli.com/en/puzzles/kakuro/
(the original website for Kakuro)

- http://www.menneske.no/kakuro/eng/
(many Kakuro puzzles of varied sizes - upto 30 - but of low difficulty)



software (resolution rules, rating)
- KakuRules, a part of the general CSP-Rules solver, described in the book "Pattern-Based Constraint Satisfaction and Logic Puzzles" and publicly available on GitHub: https://github.com/denis-berthier/CSP-Rules-V2.1



software (puzzle generation)




software (other, including non-player-oriented resolution)

[denis_berthier]

[Reserved]

[denis_berthier]

[Reserved]

[Smythe Dakota]

Under websites, I'm glad you included the Mepham site. You might also want to add:

http://www.kakuroconquest.com

http://kakuro.binaryworlds.com/hard.php

My comments about these websites are here.

These sites are not for those who want to spend 10 hours solving one puzzle. They are for "recreational solvers" like myself, who work manually, either on paper or on screen, and prefer puzzles that generally can be solved in an hour or less.

Bill Smythe

[Smythe Dakota]

.... http://www.menneske.no/kakuro/eng/ ....

I would recommend you take this one off your list. The first puzzle that came up for me was billed as "very hard", and although it wasn't the easiest puzzle I've ever seen, it certainly didn't live up to its billing.

There is a more serious problem, too. You cannot enter digits on-screen, so you must print it out. But that doesn't work either, because the dark squares don't come out dark. After printing, you must look back at the screen to see which cells were supposed to be dark, and blacken them by hand on the printout.

My rating, on a scale of 0 to 10: 1. I'm reserving 0 for any site that publishes puzzles with multiple solutions. At least this one didn't have that problem.

Bill Smythe

[Smythe Dakota]

.... http://www.nikoli.com/en/puzzles/kakuro/ ....

Puzzles aren't harder just because they're larger! These 21 by 11 things aren't more difficult, they're just more tedious.

I can't evaluate this site, because to see most of it you have to become a paid member. The sample puzzles were OK, but not spectacular. I couldn't figure out how to put pencil marks in cells, though apparently there is a way, because at one point I somehow got a tiny digit to appear. But I couldn't reproduce it!

Another problem is that the grid that pops up to choose 1-9 obscures part of the puzzle you're trying to solve.

Bill Smythe

[Smythe Dakota]

.... http://krazydad.com/kakuro/ ....

I tried one of the 10x10 ones (about in the middle in terms of the size of puzzles on this site) and found it childishly simple. Apparently KrazyDad really is a father, composing these puzzles for his kids and their kid friends. These puzzles cannot be solved on-screen, but they print out well for easy paper solving. Considering the technical problems with some of the other sites, I'll give this one a 5.

Bill Smythe

[Smythe Dakota]

.... http://www.atksolutions.com/flashgames.html ....

This, of course, is the granddaddy of the Kakuro websites. It has a great user interface for on-screen solving, including pencil marks. Its puzzles are more difficult, probably, than just about anybody else's. I think I'll stick to the Easy or Medium. Can't help but give this one a 10.

Bill Smythe

[Smythe Dakota]

.... http://www.sudoku.org.uk/kakuroflash/kakuro.html
(the Kakuro part of Mepham's website) ....

As I've said before, I really like this site. The puzzles are just the right level of difficulty and interest. One almost invents a new solving technique every time one goes to this site! Not as difficult as the ATK puzzles. I prefer to do this one from a print-out rather than on-screen. I give it a 10. It's just past midnight, so another puzzle should be available there right now. See you in a few minutes!

Bill Smythe

[denis_berthier]

Hi Bill,

Thanks for your contribution. I've added the websites you mentioned. As for Menneske, in spite of its low evaluation, I think it's better to keep it (because it is an often found reference) and to refer to your evaluation - but I put it last in the list.


Do you have any references (books or websites) about resolution rules ? I realise that, if we wanted to do the same lists for Sudoku, we would have pages and pages of references, but we can't find many for Kakuro.

As for the classification of puzzle difficulty on the various websites, I've noticed that none of them is very consistent. Even the hardest of atk have very different levels (measured by the W rating).
But rating is one of the hardest things and it depends on which type of rules one is ready to use.

I agree that large size does not imply difficult and, like you, I've seen very large puzzles of very low interest. I noticed that a high density of black cells among the white ones often indicates an easy and boring puzzle. But this is not always true; more than density, a relevant criterion seems to be the arrangement of black cells, more precisely the width of the white paths - something very difficult to formalize.

[Smythe Dakota]

.... like you, I've seen very large puzzles of very low interest. I noticed that a high density of black cells among the white ones often indicates an easy and boring puzzle. ....

True. And especially if there is a long staircase consisting of just 2-digit clues. Once you figure out one step in the staircase, all the others fall into place trivially.

.... more than density, a relevant criterion seems to be the arrangement of black cells, more precisely the width of the white paths ....

I agree again. Wide white paths tend to reduce the number of "gimme" clues. If, however, the white paths are too wide, or the black cells too few, that's an almost sure sign of a puzzle with multiple solutions, an unforgiveable no-no in the puzzle world.

More later.

Bill Smythe

[Smythe Dakota]

.... http://www.kakuroconquest.com ....

I'll give this one a 9. The interest level is just below that of the Mepham puzzles. The difficulty is sufficient, if you go to the highest level (9x11 expert). The on-screen user interface is the best I've seen in Kakuro. If you want multiple entries in a cell, all you have to do is type them all. If you want to turn multiple entries into a single entry, just erase all but one. No need to fuss around creating and then deleting a "pencilmark" icon. Not suitable for hard copy, as the diagonal lines and dark cells are missing in the print-out.

.... http://kakuro.binaryworlds.com/hard.php ....

The "hard" ones aren't all that hard, usually. There is an annoying imbalance of digits -- tons of 1's and 2's, hardly ever any 8's or 9's. Cannot be done on-screen. Best-rendered display (for printout purposes) I've seen in Kakuro. It gets a 7.

Bill Smythe

[Smythe Dakota]

Now that the Mepham site has been gone for a couple of years, and the ATK site is but a shadow of its former self (many puzzles have been removed, all the puzzles now have 3-digit puzzle numbers instead of 5-, and the possibility of a puzzle coming up that you just solved a few minutes ago has greatly increased), I'd like to add another to the list. It used to be called Kakuro Authority, but now it's http://www.kakuro-online.com/.

Compared to ATK, the puzzles at the above site are easier. If you liked ATK Medium, you should stick to the Hard puzzles at Kakuro Authority. Overall, the website is clean and has a lot of nice features.

Bill Smythe

[kakuroatk]

Hello Bill,

Your assessment description of Kakuro ATK game as

is but a shadow of its former self (many puzzles have been removed, all the puzzles now have 3-digit puzzle numbers instead of 5-, and the possibility of a puzzle coming up that you just solved a few minutes ago has greatly increased)

is entirely false and inaccurate.

Our Kakuro game located here: https://www.atksolutions.com/games/kakuro.html

In fact, on the contrary, version 3.0 has the exact same # of puzzles as it has for the past 10 years (if not more). The only difference is the game no longer requires Adobe Flash Player in case you haven't read will end at the end of 2020. On top of that, unlike the flash version, you can now play this game nicely on an iPad or Android tablet.

If you don't have internet with the cached game or crappy internet, the database will randomly choose a puzzle from only few select puzzles and not from the entire database of puzzles.

If you have normal internet then it should work exactly as it has for the past decade.

Anthony