Logic Masters India announces March Sudoku Test — LMI Spring Sudoku Test

By Francophone Sudoku Authors

Date : 26^th and 27^th March

Length : 120 minutes

IB and Submission Link : Here

Sudoku Theme is based on 'Spring' - Checkout the very interesting IB.

Based on suggestions from paper solvers, in this Sudoku test, rows / columns will be marked on pdf.
There will be a separate form for paper solvers for entering the answer keys.

See image below or login in the submission page to have a look at the new form. This form has one "Submit" button. Clicking on this button will submit all Sudokus that is filled in the form.



Like the LMI puzzle submission system, this form will do basic validations and warn if there are any entry mistakes (e.g. entering letters or 0 when 1-9 is expected OR entering less than 9 digits). If there is no warning, the text box color will turn white. See right textbox for "Greater Than and Killer" Sudoku above. [Please note that no warning does not mean answer is correct ]

Also note the tabs on the top of text boxes. To fill answers a different set of sudokus, click on the respective tab.

Answer validation
It is expected that for one particular Sudoku , a player should enter the answer either using the Paper Mode or using Online Mode. If the same Sudoku is submitted using both modes and only one of them is correct, it will be left to organizers to decide if points are to be awarded.

Different Sudokus can be submitted using different modes.

For online solvers
Show Cells to fill button is removed. Instead, the image will be marked with arrows specifying 2 rows or columns or a combination of those.

Hope everyone finds this feature useful. Please share any suggestions/questions/comments you may have.

All the examples are solvable online - Login and Click on "Show Examples"

I think no points should be awarded in such cases as, otherwise, this system can be (mis)used to make answer guesses.

Consider this situation -
Player X solved one Sudoku - while submitting, he first thought he will use Online mode, typed in 1 digit. Then decided to use paper mode, and typed the answer using text boxes.
So, logically he submitted using 2 modes, and one of them is wrong, and one is right.
But I think we should give points.

Of course, here we've completely different "Submit" buttons, so that situation may not arise.

[btw, player X was Akash in Double Delight ]

Well, it may arise. The reverse situation is more probable.

A very interesting and intriguing IB.... Having taken part in Sylvain's No Alphabet Contest, I am definitely looking forward to this test.... and knowing the French author team... This test is going to rock :)

Rishi

A very interesting IB. Only request is use of less number of colors so as to avoid confusion while printing on a B&W printer.

Indeed there is a lot of colors (in order to match with the theme of spring), but it should not affect printing in B&W.

Do the colours in "Greater than and killer" mean anything from a sudoku perspective?

As Ours Brun said, there will be some colors inside grids. It was hard not to be tempted using colors as the theme of test is Spring . However, we prepared grids (especially extra-regions) such that there will not be confusion while printing on a B&W printer.



No, nothing. You can solve this grid without worrying colors.

Fred

In sundoku, there are eight possible ray directions. If a ray is not marked (like in the example), does it imply that the numbers on that line CANNOT be in decreasing order.

No, it doesn't mean that ! There are no restrictions on cells where there isn't any ray, no matter if one could imagine a ray in that direction.

(The real fact is that I failed to build a 6*6 grid with an 8 rays' sun - if someone achieve this, I would be happy to see )

Fred

To be crystal clear concerning colors : colors don't have any importance, on any puzzle. They are purely decorative ; we were wishing to make this test a "festive" one, so, as Fred said, it was nearly impossible not to put some colors in...

You really need not worrying about that. You'd better worry about the puzzles themselves...!

Haha !!!

Don't worry, be happy !

Please stop scaring me

Rishi

happy as always!!! :-)
I am not able to understand the double sudoku. I am clear with the rules but not able to get an start in the sample puzzle in the IB.
Any volunteers for step by step help.....

Starting point are the 2 R's. There are only 2 ways to addition some 1-6 digits with result 18: 1+2+4+5+6 or 3+4+5+6. the consequence is that the 3 should be on first or last position, and on the opposite you have a pair 12. So you have 3 on R4C6 and R6C5, Then also on R2C4 (just classical placement). Then you can study the "E" columns where 2-3 must touch each other and 1-4 also.

I think that give a good start !

Fred

Neeraj, look at row 4.... the value of R is 18... now in a 6x6 the sum of all numbers is 21.... so number 3 is the uncommon part of the 2 way sum...
so we need 3 at one end and the numbers 1&2 at the other and 4,5,6 in between. Since 3 is already there in Col 1...R4C6 is a 3 and R4C12 has pencil marks of 1,2.

I have the images for solution ready but I am getting a server error when trying to upload...

Rishi

Thanx Rishi and Fred.............
That was excellent......... i cud solve it now....

The online example image (SunDoku) is now marked with Arrows.

I think the best decision is to take into account the last submission, whether by one or the other mode. A player can solve on paper, submit, and then realize there is a mistake. Perhaps he choose to solve again with interface, and submit again. Or the reverse situation. Of course, if the first submission is correct and the second one not, it's a pity for the player...
So please, don't submit a false code if you had already submit the right one

Fred

That seems ideal. We'll stick to this rule (at least for this test, and revisit in the next test if required)

Instructions in Chinese available in SudokuFans forum - http://www.sudokufans.org.cn/forums/index.php?showtopic=247

After reading the translation at sudokufans forum, I'm suddenly having a question about Jigsaw Wordoku.
Will the word (or letters to be used) given? Or players have to be find it as part of solving.
In the example it is clear since U is repeated in one column.

This is a good question.

Deb, I send you an e-mail about it in a few minutes.

Bastien

We are making an experiment - this test starts 6 hours earlier than regular LMI tests.
The scheduled end time is same as regular LMI tests timings.

Please check the exact timings in the submission page

We finally take the decision to write the word (whose letters are used in the grid) in the instructions of the puzzle. So if you want to save a few seconds, read the instructions of that puzzle before solving !

Fred

Password protected booklet uploaded. It has 12 pages, each page has one Sudoku. [ There is no cover page ]

As mentioned earlier, the test starts 6 hours earlier than regular LMI test start time.

Yes, Fred, it is a challenge, but I think I succeeded!



I tried everything and it's really impossible to catch the last cell (R1C1) with the decreasing ray.

I expect a lot of suns and flowers this weekend.

Nikola

Nice, Nikola ! Good Idea to shorten a Ray to achieve this. I think it's the only way, but I'm not mathematician, so I do not want to do a strict proof

Good luck for the tournament !

Good luck to all and may the best win!

Fred

Thank you very much for very nice test! Normally I cannot solve sudoku very quickly, but i tried to do my best :) I broke some puzzles, and i couldnt fix them, especially i am very sad about "mixed", i had almost finished, but i hadnt enough time for it :) In any way, i like very much, and i must say that "Killer 0-8" was amazing!

Thank you very much again,

Serkan

Thank you, Serkan. I'm sure your comment will reassure Bastien, who was not very satisfied by the killer 0-8 (he's the author) and wanted to remove it from the test. Fortunately we managed to make him change his mind

Fred

What is the password for the puzzle booklet? I am not able to find it in the site.

You have to login at the submission page, click on "Start Spring"
After that the password will be shown (in red color)
You can open the pdf using the password OR you can solve online

You've to submit within 120 minutes after you "Start Spring"

Good selection of puzzles - the variations were eminently enjoyable. Thanks to all the authors for this test.

This puzzle is a whole story by itself, so I will keep quiet till the test is over, but reading the word "amazing" from Serkan is for sure a huge satisfaction and reassurance.

Thanks ! (and indeed, thanks to the team for having encouraged me to keep this puzzle)

I dont like tests that are too short. I generally prefer longer tests.
I dont like tests with puzzles that are too complex or very difficult to understand and implement.
I dont like tests with puzzles that are difficult to solve and need a lot of guesswork.

Spring test is just the type of test that I love. A little lengthy, beautiful sudoku variations, some new, some standard variants, some tweaked variants, absolutely fun-guaranteed test. There are some things I want to tell, but I have to control myself till the test is over :-)
And a silly stupid mistake cost me Double Sum's points. Been very erroneous in the last few tests :(

But, great work by the team!

Thanks Rakesh and Rohan. We tried to make this test as fun as possible, and your comments tend to confirm that we did achieve our goal.

By the way, Rohan, I totally agree with the three points you exposed, so it is quite reassuring to see that, according to you, the test didn't fall in one of these traps. Looking forward to have some more detailed impressions from you (of course, even bad ones, if there are).

Really fun test with some great puzzles. Lots of creativity with great theming and a few phenomenal variations. My only possible complaint is that the dark green is a hard color to write on/read but it was still nice to see so many different ways to welcome Spring.

The new answer submission system was also a great improvement, so thumbs up all around.

I'm sort of a mathematician, and I think I proved it (albeit via brute force). At least with the sun in the middle 2x2 cells anyway...otherwise I think it's relatively easy

Look forward to taking this test after dinner!

Yes, it's implied by the fact that a ray of one-cell length is not really relevant !

Some of the puzzles were very well done... others such as the Jigsaw Wordoku are a pain in the ass when you are solving it with a keyboard. I didn't like the double sum sudoku either which isn't the kind of puzzle that's easy to do online with all of the ifs and thens involved with solving it. I didn't like that it could appear to be right until you got to the end and reached a contradiction, and using the letters on the sides made it unnecessarily confusing, when numbers on the side would have been sufficient.

Again, I think the puzzles should not just be designed for people who solve them on paper, but also for those who solve them on the site and don't use photoshop or other picture making programs to help you make enough notes to make it solvable.

David, we take note of these remarks. Even if we knew from the beginning that the test is both for online and paper solvers (we are familiar with the site, I played some tests with the interface), we may have a bit forgotten this constraint when creating the puzzles, concentrating only on the spring theme and some interface limitations deb talked us about.
We didn't thought about the fact that it's not very convenient to solve online a grid with letter inside, for example.

We hope that, however, you enjoy the other puzzles, on which you demonstrate you are one of the best player over the world.

Fred

Indeed, outside letters are less practical to use than numbers and we knew about it, but they are here on purpose.

As Fred just said, we didn't really think about the practicity of solving the "letters puzzles" online. We focused on several other aspects of the test in order to make it as convenient as possible (also for online solvers), but unfortunately we forgot some of them. There is always room to improve the system...

I thought the paper submission thing worked very well. Sadly as I was waiting for everything to print out I did the classic in the web interface and somehow managed to lose my answer by the end of the test. Never mind.

For what it's worth I thought the set was set at just about the right level. From a designers point of view, everything was very pleasing. Sundoku is a lovely idea, the classic solved really nicely (remarkably so for a classic), and the Sudokurve was very creative. This is without mentioning the excellent challenging puzzles at the end of the test haha!

I also solve the puzzles online and I agree that Jigsaw wordoku was difficult online. I eventually broke this puzzle after spending a lot of effort. But I thought the solving experience in Double Sum Sudoku did not suffer even if you use the online interface. Using letters or numbers does not make much of a difference as the reference was shown next to the sudoku grid. If anything, the killer was a bit problematic for me at some places, as the '0' candidate in some cells was overlapping with killer clues. I had to restart the grid from scratch as I missed reading a zero while solving.

But the overall experience from the test was a very positive one.

Last night my friend was giving spring on my system, today when i am trying to login through my account, even after my login when i go to spring sudoku it says 'vibhor87 has completed spring' which is my friends login id..
what should i do about this

Delete the Cache on your comp and try logging in again...

Rishi

Please check your inbox

i did clear the cache dis tym, but even that doesnt help man!!!... do something i seriously wanna try this level

From the database, I see that you've started Spring. So I hope the issue is resolved.

One request - In this forum, please write in proper English. Some of us are much older than what you might be thinking. I especially have lot of problems understanding this sms-like language.

Mind blowing.........great test..........
This new submission system is excellent.

We identify this little problem with Deb, that appears on each test including a killer sudoku.
If someone has an idea to improve the system for killer sudoku, you can speak we Deb, he'll be happy

Fred

Thank you, Neeraj !

A great set of puzzles.... after a long time something which made me think for a long time... A few of the puzzles were simply superb... great job Authors...

rishi

What can I say ? A big thank you for these kind comments.

=> Thomas : My bad about the dark green. I am the one who designed the puzzles and I couldn't access to a printer before the test, so I couldn't exactly figure out what the color would look like. I keep the remark in mind for future tests with colored puzzles.

=> Tom : We went through several doubts concerning the overall difficulty of the test ; before the start, I was a bit afraid that it could be "too easy" ; then I saw the first results and it appeared that, on the contrary, it was probably slightly too hard. So it is good to read that some top solvers have found it well estimated.

=> Rakesh, Neeraj, Rishi : I am really happy that you liked the test. It is always difficult, when you build puzzles according to a "theme", not to fall into the trap of sacrificing quality for aesthetic. But of course, that is what makes the construction of such puzzles interesting.

Yet a few hours before the complete results...

Ah - well that'd certainly be my advice to any would-be test creators. Your own puzzles are almost certainly harder to other people, and so any test you put together will be harder than you think it is :). (Unsurprisingly) if you'd taken my test times for the UKPA sudoku I'd have ended up significantly quicker than far better solvers than myself.

Besides, I think if you concentrate on making hard puzzles, rather than creative puzzles, you won't end up with anything particularly good. I believe the author has to have some fun too!

We applied a little different method for testing than usual, for this test, I'll explain that tomorrow if you want

I am well aware of that ; each time I organize a tournament, I take this fact into account... and every time I realize, once it is over, that I nonetheless underestimated the difficulty. Fortunately, we were six authors this time, so we had a more global vision (and yet, the test was a bit hard...). And I just see that Fred proposed to tell you some more tomorrow, so I am gonna shut up now.

Bastien, if you want to talk about that now, don't hesitate
I'm just a bit tired and my English is very poor, so that each message I post is a real effort. That's why I planned to speak more tomorrow

Fred

No, precisely I am also a bit tired so I welcomed with great joy your message. Right now I just need to get away from screen, grab some book and read until the test is over (I definitely won't be able to sleep till I know the final results, so...).

Ah, so you're not creating grids now ???

Thank you to the authors of these puzzles. This was a wonderful set -- I think it rates as highly as any I've ever played.

Are you suggesting that I may be addicted to puzzle creation ? Look, we have met several times by now, we begin to know each other. I ask you, during one of those times we met, did you ever see me, even once, creating puzzles ?

Rhetorical question, you don't have to answer.

Please, do not answer.


By the way, you just reminded me about an idea of a puzzle I had last night and forgot to put down on paper.

Thank you, Jason !

The test is over. You can view the results here

Congratulations to Thomas, Michael and Jason who take the places on the podium ! Thank you all for participating, I hope you had fun doing this test. We will post more detailed comments tomorrow, after a good night's sleep. (It was tiring to watch you playing )

Also thanks to LMI team and especially Deb for the great work he does for these tournaments. It's enormous !

Fred

Edited by Fred76 2011-03-28 6:00 AM

From the results I can see that Double sum Sudoku had the least number of solvers, and the lowest %correct answers. I find this a bit intriguing, as, in my opinion, this puzzle was fairly straightforward with well defined starting points (columns/rows marked with 'E'). In fact, this was probably one puzzle which was over-valued, and definitely easier than some of the other high-pointers.

All killers were very good.

Thanks to all authors for such a nice welcome to Spring ( i know we are 1 week late in welcoming, but we had some scheduling problems :-)

Very satisfying to see good Indian results as well, 3 positions in Top 20 (Rohan, Rishi and Rakesh - all Rs). Rohan did a mistake and lost the highest pointer sudoku (he mentioned that he wanted to write something about the test after it is over, may be about this).

Also good to know that the "Paper Submission Mode" is appreciated by all. We'll continue using it. In fact, I think we missed the trick by continuing the 'old method' for such a long time.

Thank you everyone for participating. Please leave any other feedback/suggestion you may have.

Yes, this was an issue which Fred and Rakesh pointed out during pretesting. Unfortunately, there was not much we could do.
Without spending significant effort, we thought we'll show the pencil marks in different color, but we dropped the idea in the end.

A small note about Paper Submission Mode
From the database, I found that as many as 6 players submitted same Sudoku using both modes. Fortunately for them, both the answers were correct.
But please remember that, it is not necessary and definitely a waste of time (and error-prone) to submit same Sudoku using both modes.

Well, I do know that some players don't read forum, and might make the same mistake next time :-)

Great test, as I predicted. Thanks to all authors! Please, repeat this before the start of each season.

Nikola

Great test indeed... my personal Favorites were the 0-8 Killer and the Inequality Killer.... The puzzles opened up beautifully and very logical....

made a complete mess of the last puzzle in the last 20 minutes... :(

Rishi

I made the mistake of trying to do this puzzle late at night and very tired - but it was the only chance I had. I really enjoyed the puzzles, but stopped after about one hour when I (after solving the first two) got almost to the end of the jigsaw wordoku and realised I had stuffed it up.

It is hard for me - with a four year old, the only time I get to work on things is late at night when she is asleep.

Loved the look of the test and will add them to the pile of puzzles to solve on the train.

Aesthetically beautiful puzzle set. Congratulations to the setters.

Puzzles 1-6 went smoothly for me - logical solves and appropriate points values.

Puzzle 7 (Sundoku) is where things started to go off the rails. I couldn't solve this puzzle logically and had to resort to guessing. Same for puzzle 8 (Extra Regions). Such a beautiful grid design it seems a shame not to find a logical solve. Would love to know how other people cracked this one. Puzzle 9 (Jigsaw) was just horrible and I couldn't finish it. Jumped to puzzle 11 (0-8 Killer). Unlike what other people have said, I cannot see how this can be solved logically. If it really is a beautiful solve, please share your insights.

What really annoys me, though, is that the two puzzles I never looked at were really easy. Puzzle 10 (Mixed) is a lovely puzzle with a very simple logical solution. Puzzle 12 (Double Sum) is easy to solve quickly by a mixture of logic and trial and error.

I think I will enjoy solving some of these again without the time pressure.

A few words about the tournament.

1. Preparation.
When we got in touch with Deb in late December asking when we could organize a monthly test, he told us that the months of January and February were already taken. We decided to organize the test in March.
Therefore we had the idea of ??building grids on the theme of spring. We made a brief glimpse of what could be done: use letters (puzzle 1, 9 and 12), date (20 March) (puzzle 3 and 11), and try to symbolize, to image the wildlife , plants, sun, etc... inside grids.
Then we worked on our own and we sent grids to each other when they were created.
2. Testing.
Since we were 6 authors, no need to seek external testers. Everyone can test the grids of other authors. But, usually, with testers that solve all the grids, we can make a mean time and compare the difficulty of all grids. Here, each author does not test its own creations. Therefore, we thought that the best time of us for each grid would be an excellent reference time and comparison to assign points.
Thus, the sum of our best times for each grid reached the total of 1h50. We thought it was a good estimate of the time it would take for some better players to complete the test, and that 4-5 people would be able to do so.
We failed to take into account the fact that, although some are better than us, it is not possible to beat or approaching the reference time on each grid, and during the 2 hours of tournament, even being at the best level, there are grids that can be solved optimally, and others where you can lose several minutes compared to the ideal time would be done in theory.
Thus the grids were a little too hard for a 2 hours tournament, nobody could fix everything in time.
3. The tournament.
Hideaki Jo, David Jones and Thomas Snyder were the first of the favorites to play and thus give give us a good reference about the difficulty of the test. Seeing none has succeeded in solving all the grids, we realized that the test was a little too hard and it would be difficult to find someone who could do anything (but may not be impossible?). Thomas was very close to doing so. He still had 8 minutes to solve the sudokurve. Unfortunately the code he gave was false. Throughout the weekend, we waited to see if anyone was going to beat Thomas by passing the entire grid. Sunday, Deb sent us a link telling us that there was a puzzle weekend in Germany, and that one should not hope too that the best German players taked part. 5 minutes later he was denied by Michael Ley, who entered the tournament. And he very nearly created a small surprise, making all the codes, but also with an error on the sudokurve. Thomas and Michael have dominated the tournament with a fairly comfortable lead on the 3rd. 3 hours from the end of the tournament, when we thought everything was played for the first places we saw Jakub Hrazdira and Jason Zuffranieri get into the tournament. The latter manages to stand on the podium. At 13 minutes remaining, he had not made the consecutive and jigsaw Wordoku. He fails completed one of these two grids (the jigsaw Wordoku would have placed him at 950 pts without the time bonus).
4. Conclusion
With 12 grids, none of which really easy for beginners, there were many zero scores. We realize that this was not an easy test for beginners or people unfamiliar with variants. However, we hope everybody had fun solving some grids and that you will take time to try to solve others in the coming days / weeks. We thank all participants, without whom these events would not be what they are and Deb for his wonderful work. It was really a pleasure to work with someone who shows his commitment and desire to constantly improve everything that can be.

On behalf of the team,
Fred

David, I'll post step by step explanation for sundoku and extraregions, which were not so difficult, but they are some steps that are not so easy to find, especially under time pressure.




It's nice to see that there is no unanimity about difficulty of some grids . When I tested Double sum, I must say I found it very hard, and I could not find a strategy to solve it in a good time. I think all testers found it hard (best of us solved it in 17'), this is why it had so many points.

Fred

To continue my mini discussion with Bastien and Fred - another thing to take into account is that each puzzle author inevitably has his/her own style. I imagine that as a group you are well accustomed to each other's puzzles. Of course you also have the extra factors of time-pressure, printing time, answer-entry time and all the rest as you rightly say.

Very strange re the double sum. During the test itself I must have spent that last ~45 minutes on the 0-8 killer. I got about a third to a half way in, thinking to myself this will now fall very quickly, like most killers do when you get a few digits placed. Except I didn't. In comparison, solving afterwards, the double sum was quite gentle. It definitely didn't take longer than 10 minutes and was probably closer to 5. My explanation is that the 0-8 killer didn't feel very constrained at all (I'm probably missing something), and the double sum most certainly did - to the point where I thought I'd gone wrong a couple of times only to spot that actually I had made the sum elsewhere in the row/column.

I'm glad I'm in good company with the sudokurve. I thought I had it solved, but as I was entering I saw the mistake. I then decided to put it aside, and thanks to the 0-8 killer never managed to get back round to it!

This problem is fixed now.





Attachments
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I enjoyed this test. Best sudoku finish so far for me. But that is probably partly because it was only a small set of puzzles. I generally fair better with a smaller number of harder sudoku puzzles than a lot of easier sudoku puzzles.

My favourites during competition were the extra regions and 0-8 killer sudoku. I didn't need to guess for the extra regions, found the logic path quite nicely.
I spent a bit too much time on the Jigsaw Wordoku as I had at first missed the "repeated letters can't be adjacent" rule. I got pretty far with it till I realised that one.
The first time I did the Sudokurve I messed it up too, till I noticed 2 6's in a long bent row. I found the outside lines a bit too hard to follow.
The Sundoku was tricky and I messed it up twice in competition. I thought the opening was really nice, just too bad I kept breaking it.
The mixed was also very nice, although I missed the opening during competition. The inequalities did feel a little as an afterthought, as in we set up this really nice thermometer/arrows path except it's not unique yet. I thought the double sum was very hard and when solving it afterwards it didn't really feel like a solid logic path, always felt like I was doing it a bit intuively, constantly finding things that work and assuming i'm still on the right path, not being 100% sure my deductions were right.

All in all, thanks for a fun test. Now if only I can not make an entry error next time. Dumb 4.

About extraregions:



We can easily place every 9 (region 2 & 9, then 5, 4 and finally 6):



Then, we see pairs 38 and 27 in region 9:



That leads to other easy placement:



We now can view a pair 35 in the extra yellow region:



What about the cell R9C6? We can have 1 or 2... but the 2 doesn't fit, otherwise we couldn't place a 2 in blue extra region. So it's a 1 !
And the 35 pair implies a pair 34 in region 1 (by the placement of the 3 in column 3), and of course then a 16 pair in region 1 and another pair 34 in row 3. Then we can place the 5 in region 3. Here we are:



There is only one possible placement for the 1 in blue extraregion, that leads to:






What about the 7 in R6C3? impossible, otherwise there will be two 7's in the red extra region !

So it's a 2 !

Further, looking at placement of the 1 in red region leads to place 1 and 4 in region 6 !

Another extraregion analysis: 5 in Row 7 is in the green region, so there is only one possibility for the 5 in column 4: R2C4. Which leads to:



On R7C1, there is only one possibilty: the 1. Then only one possibility for the 1 in green region: R6C4. Then a few easy placements:



3 is in red region in region 1, in blue region in region2, so the only placement in region 5 is R6C5, which leads to:



We can then place the 5 in region 5, then 4 in region 5 and some easy placements:



Place the 3 in green region, then all the rest are easy placements

Solution:



Fred

I think I could have solved all of the puzzles logically, had I printed them all out and paper solved them as it appears that many people did this. I do not like contests where there is a puzzle which is made so much simpler if you can note take, and becomes a memory puzzle if you can not or an exercise in locating each key on your keyboard when you solve it online. I think the puzzle testers should have tested these puzzles using the logic masters interface, and I'm sure you guys would have realized the competitive advantage that all of the paper solvers had over anyone who did all of the puzzles online.

In the future, if contests are going to contain puzzles with built in advantages to solving it with one means over another, then the scores should be separate and based on how people solve it, or the scores should be adjusted with a multiplier for solving it one way over another. If it's not done this way, I see no reason to compete in any contests hosted on this site because it is not worth the aggravation of having to jump through hoops which many other competitors don't have to just because they printed out the puzzle.

I think LMI has done an excellent job of accommodating solvers throughout the many tests they have run, and have done their best with the sudoku tests to allow for both online and paper solving. Everyone has the option to enter both ways (or to even solve some online and some on paper if that is optimal).

Each method has its pros and cons. Solving online is often much quicker than writing for easy puzzles, avoids the loss of printing time as well as answer entry time and is also free from the transcription errors that come from typing in a solution from paper (which happen at a not insignificant rate - my US teammate MellowMelon seems to have lost two puzzles to simple typos this go around and I've certainly lost credit in the past for mistakes that were not puzzle-solving mistakes). Paper offers the flexibility of any style of notes the solver wants, and is perhaps best suited for very hard puzzles where more notes or possibly guessing become required. I don't see a fair way to weight the two approaches since it is impossible to compare these times rigorously, particularly on novel variations of sudoku.

Reading through the various comments, and testing the interface myself, I can see that online solving was not ideal for three puzzles this time around, once due to the interface and twice due to the puzzle presentation. The 0-8 killer has an issue of the first candidate (0 this time) colliding with cage values. LMI seems to realize this problem and is experimenting with solutions, so future tests should be better in this regard. The Alpha Frame and Double Sum both did something I dislike in sudoku contests (as I commented before in the Numerologidoku on the January test) of requiring extra conversion steps to get to the real data. You are absolutely right that not being able to replace the letters with fixed numbers (as paper solvers could do) is a disadvantage, so in my opinion the authors should have kept the PRINTEMPS theme but simply also printed P=16, R=18, I=9, ... along the rows and columns to save everyone from doing this extra(neous) step.

Where I don't agree with you is that the Jigsaw Wordoku was unfair for online solvers. If your complaint is "I don't know where the letters are on my keyboard", then let's admit that that is not a fault of the interface and more a variable from your specific skill at typing. Yes the numpad, and remembering 1-9 complete sets, is helpful for speedy sudoku solving, but I see no fault in going to letters either from the authors or the site administrators. Letters trips up paper solvers too as we can't fall back on 1-9 sets either.

Hearing your perspective on online solving, let me share mine from the paper side. As I and others have commented, paper had its own disadvantages this time around. The color printing seemed to take a fair bit longer than usual for these tests. For some, the PDF literally took forever to print. So instantly disqualifying yourself, or at least losing 2-3 minutes, was a likely consequence. I was 20 seconds from finishing the test and lost 3 minutes to printing. Oh well, goes with the territory. The dark green color on my printout was very difficult to write on and then read from. On both the Extra Region and the Mixed Sudoku, this caused difficulties in solving that were not necessary and also weren't encountered online. Am I threatening to quit because they used dark green and made a poor PDF file? No, but I'll point out the shortcomings so that future tests get better for paper solvers. The new entry system was a huge step forward in fairness, and everything I've ever seen has suggested the LMI organizers bend over backwards to address concerns and improve their tests. As a whole, this test did feel easier on paper, but this has not always been the case and that's just part of the competition.

So I'll agree with you in part but not in whole that there are specific disadvantages to how one goes about solving these contests. But there is no real reason or ability to try to separate online and paper solvers given the goals here of producing world championship level tests. The simplest and safest way to always accommodate online solvers is to simply do classic sudoku of easy to moderate difficulty where the applet will always well match the puzzle. There are hundreds of sites that do that online already and the competition is pretty good. If this is what interests you, please compete at those places. What LMI offers is both challenging tests, new variations, beautiful hand-crafted puzzles, and the challenge of facing the world's best competitors. I'm glad for the rich variety of puzzles we've seen here and, just like all other solvers, I make a choice to solve the test one way or the other each time it happens, and post a score under those same rules.

Edited by motris 2011-03-29 2:43 AM

David,
I definitely understand your frustration for not being able to solve the last 2 Sudokus with 35+ minutes in hand. As one of the LMI organisers (and as someone who has mostly designed the flash interface for Sudoku solving), I'll be the first person to admit that LMI Sudoku interface is definitely not the best around the internet. I'm certain that some (or many) other sites provide much more user-friendly (and powerful) interfaces. But LMI contests differ from many others with the kind of Sudokus we provide. That has been our focus. We have spent more time on making sure that quality of Sudokus is one of the best, rather than fiddling with the flash interface.

At the same time, we invite both kind of players (paper / online) to compete, and many times the pros and cons for both modes balance out. We also have seen players using both the modes in the same test (i.e. solving 6X6 grids or easy 9X9 grids online, while solving other grids on paper).

As many players pointed out, 0-8 had a problem solving online. We probably should have made a note in the forum before the contest. In other Sudokus you've mentioned, paper solves might have certain advantage. But if we decide to only have Sudokus which are fair to paper and online solvers, it will be a huge constraint for authors. Many authors would agree that it limits their creativity, and we probably shouldn't do that.

Please be assured that we take each and every input that we receive and try to work for the best solution. And we'll definitely advise our future authors to keep in mind that a certain percentage of our solvers are online solvers.

Hope to see you participate in future and make LMI tests more competitive.

Deb

Regarding pdf printing problem this time, before the announcement itself, all of us (Fred, Bastien and me) were concerned more about how the pdf will look in a B&W printer.
I printed the pdf (in a high-end HP LaserJet B&W printer) and it came out without any issues. I didn't think much about the color printing.

Frankly, I'm against using colors in puzzle grids at LMI competitions, but we made an exception in this case because of the associated theme. This is the first time we had colors in grids (even MellowMelon had to change his puzzle presentation to accommodate B&W printing).
We are unlikely to have colors in puzzles frequently, but whenever we have we'll ensure that it prints equally well in B&W and color printers. [ Oh, well, at some point in time we discussed to have 2 booklets, one in B&W and one in color ]

Regarding pdf not printing at all in some printers, I've no idea what could be the problem. But Tom C's explanation on UKPA forum seems most reasonable.

A big thank you to Fred for posting a solution path for the Extra Regions Sudoku. Beautifully done and I must apologise for my earlier comments. I have also found a simple logical solution to Sundoku and a logical (but very difficult!) solution to the 0-8 Killer. As predicted, once the time pressure was off, my brain started to work a little better.

This is the second time I partecipate to a contest.
I prefere to solve online and, as requested, i propose some suggestions.
The candidate are very small and removing them with the mouse (ctrl+click) is not so esay.
Is it possible to make the grid resizable with ctrl+mouse wheel?
I discovered today trying to solve the grids I could'nt solve in 2 hours that you can undo all the inputs.
this could encourage the tentatives,
In my opinion it would be better to limit the undos to just few steps.
Great test, anyway.

I agree that the candidates are small. And using ctrl+click is not the best way to remove a candidate...definitely not the quickest and is click-error-prone, i.e if you release the ctrl early you have to re-enter the candidates. I have not used either Undo or Digit colour feature so far. Now, that I know about it, it seems to be a really good feature and can speed up online solving a bit. I don't think there is a need to limit the number of undo steps. Can it be used for trial and error (T&E)? - Yes. But, probably, that is not a big enough reason for restricting the usage. All said, it is a good feature and can only improve the online solving experience, if used well.

Hi David. I am glad you could finally solve the killer logically. The puzzle wasn't that hard if you managed to follow the intended path, but of course this path wasn't particularly easy to spot (well, the puzzle was worth 140pts...).

Time for a global look on the test.

Generally, puzzles were widely appreciated and this is always a major satisfaction, being the main goal of each and every author. More of that, some of them got some emphatic comments, in particular Mixed Sudoku from Laurent Pierre (the man who depicts himself as a "beginner author") ; we can only be satisfied of that and it fully rewards the work which has been done.

My own 0-8 Killer also got some very nice comments and this is a great reward. As I said to Serkan on saturday, this puzzle caused me some torment. My original idea was to simply create a basic killer with 20/3 areas but after several tries, I couldn't get a satisfying puzzle in terms of difficulty. Then came the idea of using a different set of digits, and the "0-8" set appeared to offer lots more possibilities to play with - in particular, the sum "3" now admitted 3 different combinations, including a 3-cells one.
A few more tries later, I obtained this puzzle on which I had a mitigated feeling, certainly due to the fact that my previous attempts (with 1-9 set) had been somewhat disastrous. So, I sent the puzzle to the other authors but I remained a bit hesitant, not totally sure if it was really good or if it was just "better than the ridiculous previous attempts".
Finally, Fred and friends told me there was no issue with this puzzle and encouraged me to keep it ; I hadn't given a look at it since its creation, so I came back to it, found the solving smoother than in my memories, and did breathe a big sigh of relief.
My two other puzzles were the Arrow Sudoku (clearly not an incredible one, but I had it created some time ago and it fitted well with the theme ; some not too bad steps to find if following the main path, though) and the Consecutive. Again, not a fantastic piece of a puzzle but I had some score to settle with consecutive puzzles and designing a themed one happened to be a good way to do it.

Unfortunately, there were a few issues due to color (but as Deb said, the use of color was an exception because of the spring theme, so it souldn't happen again) and to the fact that one or two puzzles were definitely hard to solve online. That's a pity but things rarely go as well as they were intended to, and I think that, despite of these, the balance remains positive.


I agree. By the way, I also dislike these extra conversion steps but we thought that, by giving the alphabet table, every player would quickly replace letters with numbers and that it would be a "lesser issue". Unfortunately we omitted to take into consideration the fact that online solvers couldn't replace the letters with numbers ; if only we had thought about it, we would surely have adopted the solution you propose, or something very near.

I won't extent about WaterlooMathie's last post ; answers have already been given. Let's just say that problems are always far more obvious to spot once they have happened...

All in all, a big thank you to all the players who had a try on our puzzles. I truly hope that, amongst the various grids, everybody found some puzzle which fitted him/her.

Bastien