Top.Mail.Ru
? ?
motris
31 December 2009 @ 02:00 pm
As with last year’s entry, I’m doing this awards style and keeping the categories from last year. Commenters are welcome to recommend other “awards” for the best or worst in puzzles.
Read more...Collapse )
 
 
motris
26 November 2009 @ 01:56 am
About four weeks ago, a former sudoku champion rang a bell that cannot be unrung by claiming a fellow finalist was a cheater. While a lot of circumstantial evidence supported this case, no smoking gun was likely to be found from looking at video and photography from the event itself. Sudoku-related curiosities such as "unreasonable sticking points" or "missing pencilmarks" were unlikely to satisfy all parties necessary to disqualify the competitor. However, the tournament organizers came up with a process that could clarify matters: the contestant would be offered a second chance to solve more sudoku puzzles under closer watch to demonstrate his proficiency and to deflect the allegations of cheating. This leads to this week's topic:

What if you had to conduct a retest for sudoku? What kind of standardized puzzles or times would suffice to conclusively prove either the ability or inability to finish three puzzles in 14 minutes? How many puzzles would be needed and what would these be? Can sudoku be made "retestable" to indeed prove Eugene is detestable?

These questions necessarily lead to a discussion of mean and variance and nuances of the solving process; a fitting answer requires a careful analysis of how an actual human solver performs from puzzle to puzzle in a controlled setting. Fortunately, I know an eccentric scientist with an advanced degree in "Number Placement" who has a relevant manuscript to share with you:

Effects of Transformations of Sudoku Puzzles on Solution Times of an Advanced Solver
A Case Study by Dr. Sudoku

Abstract:


We generated five isomorphic copies of five sudoku puzzles using digit reassignment, row/column/chute swapping, and rotation/reflection. A sixth puzzle with an unusual solving property was also transformed and added to the set for twenty-six test puzzles. Our subject, an advanced division contestant at the recent Sudoku National Championship, was able to identify the grid with the unusual solving property from the set of 26 puzzles, and also identified several commonalities within the remaining isomorphic puzzles. Considering his solution times, a 15-20% standard deviation in time was observed across the isomorphic versions of each puzzle. The fastest/slowest grid outliers were then resolved without further transformation. The subject's results suggest that the likely mean and standard deviation in solving time on an exact duplicate is very close to that of a transformed grid.

We also examined how transformations would affect computer ratings, specifically those of Scanraid Sudoku. Both number ordering and top-to-bottom, left-to-right biases were observed in the grading of isomorphic puzzles. In one extreme case, a 90 degree rotation of a puzzle led to a 50% increase in the rating for the puzzle. While the varied ratings may apply to the most esoteric human solvers, who persist with perfect top to bottom or 1 to 9 scanning, these ratings in general seem inconsistent with the expected human solving experience of sudoku.

Read more...Collapse )
 
 
 
motris
23 November 2009 @ 03:01 pm
(I'm sure an official announcement on philly.com will come soon, but an email signed by Will Shortz qualifies for me even with the many typos. Here, for the sudoku community - whether advanced, intermediate, or beginner - is finally some justice; nothing can fully restore the finals, but this is something.)

Dear Thomas,

We are pleased to announce the final results for the Advanced Division of The Philadelphia Inquirer Sudoku National Championship, held on October 24, 2009, following an investigation regarding a possible violation of the Championship rules. First place and $10,000 was awarded to Tammy McLeod from Los Angeles, CA. Thomas Snyder from Palo Alto, CA. won second place and $4,000. Chris Narrikkattu was awarded thrid place and $3,000 as a result of the disqualification of Eugene Varshavsky.

Mr. Varshavsky's poor on-stage performance during the championship finals led to a thorough investigation of his qualifying round solving time, and ultimately resulted in his disqualification.

Over the last three years out Championship has established a reputation as the championship for everyone and has a strong following in the advanced, intermediate and beginner sudoku community. The integrity of this competition remains our highest priority and we hope you will join us again next year for our fourth annual Sudoku National Championship.

Will Shortz


ETA: Now the Inquirer's story is out: 3rd Place Winner Disqualified in Sudoku Scandal
EFTA: Philly.com/sudoku official statement
 
 
motris
16 November 2009 @ 07:06 am
TIME.com was following Wei-Hwa and me at the recent Sudoku National Championship and the video piece was just released. Aside from some minor factual flaws (I turned in my final puzzle at ~4:14, not ~7:30 for example), it captures the whole championship - even Eugene - really well. (Note: I'm not getting the embedded video to play right from lj so you'll likely need to click on the link above)




ETA: Some curiousities to add to the story: this video may actually show Eugene finishing the 3rd round (which is quite a weird moment to watch as he stares at the camera instead of just handing in). While the proctor does not collect his paper immediately after writing a time on it (leading me to initially speculate this could be an earlier round), I've been told a separate runner collects the papers so its not on camera. You'll notice that Eugene was not in this seat near Wei-Hwa during the round 1 filming so he wasn't competing then or wasn't competing there then, consistent with what we've heard about mid-competition registration. Still, there is no doubting Eugene's final puzzle board, shown here quite clearly after 8 minutes, with impossibly slow progress for an advanced solver. If he wasn't cheating on paper, he was certainly throwing the competition on stage.
 
 
 
motris
11 November 2009 @ 07:00 am
Sudoku contest competitor to be retested - so, maybe someone found Eugene after all (or his not showing will make a choice easier?). This could get weird and I'm not sure what this extra step means in terms of how the investigation is leaning. Also of note, Phil Irwin from the chess community is the first to publicly associate the chess "player" from 2006 with the sudoku "solver" in 2009.
Tags: ,
 
 
 
motris
30 October 2009 @ 09:00 pm
No real further developments in the Sudobomber story over the last few days; the latest word is that the intermediate and beginner prizes will be released but no word on any changes in the advanced division.

I should be getting ready for the WPC, making instruction/preview posts here or something, but I have not had any time. I skimmed the instructions and saw that one thing I hypothesized the Turks would do from past discussions (a team playoff) is indeed happening. No details on the individual playoff besides a dozen go in, but their national championship used a belarussian-like set of weighted heats which might be what they do again. The OAPC round will use OAPC like grading/entry without marking full papers which feels right. A future "What if?" will likely revisit the concept of what/how much such be graded to confirm an answer to a puzzle at a competition.

The lack of more detail in my WPC thoughts when I normally share a ton of thoughts here is in part due to my being on a really interesting and fast developing project at work; I have been doing extra hours for the last month to get this data ready for public view. Sleep has been irregular and inconsistent and I can't tell you what time zone my body is in right now, but it won't be any more out of whack when I land in Turkey I guess. I just really worry I'll have another late day 2/day 3 shutdown but will certainly try my best to win the one title I want to win before I run out of opportunities to compete.
 
 
 
motris
Sudoku prizes frozen in cheating probe - the Inquirer is still incorrectly reporting that the second and not the third qualification round is critical here, but they are also mentioning that "After the competition, the blogosphere quickly began buzzing with skepticism and outrage. Chief among the bloggers was second-place finisher and former champion Thomas Snyder, who wrote competition officials a scathing 'open letter' that went viral." I'm not sure its exactly viral, but my presentation seems effective and, more importantly, incredibly public, given all those who enjoy what my blog should be about which is sharing tips and puzzles. (To those who are here just to follow the story but enjoy puzzles, please take some time to explore some of the links on the left of my blog-page, such as Puzzles I've Written or Thomas Snyder Outdoes the NYT KenKen as this blog is meant to demonstrate innovation, creativity, and beauty in logic puzzles - its The Art of Puzzles - and not just reveal details of a sordid cheating scandal.)

While the hold on prizes applies to the finalists in other divisions, I do not expect any changes anywhere else - I watched 4/6's of those boards from my position to the left of the stage and spotted nothing odd on the ones I saw - just true sudoku solving styles (two heavily candidate-based, one entirely noteless until he got stuck, ...) slowed down due to format and nerves, as would be expected. Still, its certainly worth reviewing everything because this championship's integrity, and this host's integrity for next year's WSC, is really at stake to me. This at least shows the organizers are taking things seriously. There will also need to be a real addressing of other concerns of the sudoku solving community before the next championship, but this "scandal" must be addressed right now.

This whole incident brings back to me the funniest part of my first championship win, on Yahoo's front page, with one option, right under the link to the story, for how others might catch up to me. That search then was frankly useless, but finding "ways to cheat at Sudoku" will hardly be a novel concept anymore.

Tags: ,
 
 
motris
27 October 2009 @ 06:52 am
From the Philadelphia Inquirer: Possible Cheating Probed at Sudoku Tournament (they get a fundamental point wrong - its round 3 not round 2 that matters) - let's hope the evidence (such as the appearance of his test papers and whether it looks like a grid someone would have when solving a puzzle, versus a grid someone would have when copying/being read an answer) leads to a fairer resolution here. There is still no way to restore a final with three advanced competitors, but not rewarding someone who gamed the system is a good start.

[ETA: NPR is reporting on it as well as standard AP wire. While indeed the Weekend Edition's Will Shortz is an organizer leading an investigation, I believe my contributions to exposing this cheater should not go unmentioned as they also borrow the frame I gave the story and the quotations around this person's name here on this blog.]

[EFTA: I've been interviewed a couple places now, including Philly's WHYY, for developing coverage tomorrow. Will Shortz has already been interviewed about this on All Things Considered and a couple new details are emerging from the cone of silence around this investigation. Most significantly, Eugene registered not just the day of as a walk-on, but also in the middle of the tournament and he only competed in Round 3. This is quite significant IMO. My observations of him after he finished 2nd is so far the only eyewitness account of this solver during the general qualification.)



The Sudobomber aka Eugene Varshavsky, in "action" (or I guess, inaction). The big headset bulge is expected in the finals, but who knows what was under the hood earlier.


Dr. Sudoku aka Thomas Snyder, in action and motion-blurred, before his mistake.

To think the next four minutes would take me through the whole range of OMG!!! I Won! to (gulp) two sixes to Congrats Tammy to No, Will, there are three errors on my grid to WTF is going on over here with "Eugene". Nothing is simple in the world of puzzles.
 
 
 
motris
26 October 2009 @ 11:59 am
I'll place "evidence" here as solvers or others send it to me of the likelihood something fishy was happening with Eugene Varshavsky at Saturday's tournament. These are screen captures from the Inquirer's own edited video. The first is the grid, as it was during the awards ceremony which was certainly after he stopped, and at increased contrast difference. It has 2 observable placements in it, both in row 5, and a suggestion that the 9 in R1C3 may be there too (eta: confirmed from other images now). It is however not the most focused image and does not tell how this grid got to this state, if erasing happened, etc. Still, having this for 8 minutes of work on the puzzle after demolishing 3 hard ones in 12-13 minutes to qualify is simply not possible.



The second is the only picture of the Sudobomber minus the hood from the video as well; I ask that anyone who knows members within the chess community who may have been at the World Open in Philadelphia three years ago to see if he is recognizable, with a large bucket hat over his head and ears or not.

 
 
motris
25 October 2009 @ 11:24 pm
I never thought, given the level of distaste left in my mouth by serious organizational mistakes, bad puzzles, and other controversy at the World Sudoku Championship in Zilina, Slovakia, that I would ever again spend most of a trip back from a puzzle event in the midst of another serious controversy and with such serious disappointment at many parties. We'd laugh before the tournament about my declaration on my blog, in answer to a question from a competitor about music that popped up over here, that my opinion that "[d]uring the rounds I cannot imagine any listening devices ... are allowed", was trumped by a facebook organizer post basically saying "yes, you are :)" with that extra friendly smile. I'm betting at least one other competitor is wishing now that basic steps taken during any other testing situation (no cell phones or electronic devices for example) were in the considerations of these organizers when in reality a lot seems to be missed, in part because of either failed imagination or limited experience competing in (not just running) a tournament.

So, here I am again, with a different controversy that needs addressing. Again I am left sitting on a plane writing a letter in my head to the organizers of a sudoku tournament to hopefully correct basic mistakes now and in the future in the organization, proctoring, and ranking of sudoku competitions. I do not believe I am a lone voice in my concerns that impropriety has occurred at the 2009 Sudoku National Championship, but I am a respected member of the puzzle community and so I am speaking out in hopes that this concern is addressed. I encourage feedback from other observers who may have additional memories or photographic or video evidence of this competitor to help solidify an understanding of what was going on with the "man under the hoodie." I've done my best to report what I know and what I saw as someone who also had a lot else on his mind.

Open Letter to the Sudoku community and the organizers of the Sudoku National Championship about the potential cheating of Eugene Varshavsky during this Saturday's tournament:

It is with a heavy heart and with the fullest consideration of the seriousness of these allegations that I am writing today. As a past US and World Sudoku Champion, a person who has solved (and watched others solve) enough puzzles to know a lot about the art of solving a sudoku puzzle, I have significant suspicions about the performance of a contestant in this Saturday's Sudoku National Championship.

Just as in college exams, sports, or other venues, intellectual competitions are certainly not free of people trying to use technological assistance or other cheats to gain an edge on more formidable competition. In 2006, for example, a suspected incident of cheating occurred in the World Open Chess Tournament. Against Grandmaster Smirin, a relatively unknown player wearing a hat the whole time performed well beyond expectations and ranking to beat the Grandmaster. After some suspicion was raised, this unknown disappeared to a bathroom where after ten minutes he was searched and nothing was found. Under closer watch, without the possibility of using unallowed assistance, the performance of this player returned to more expected levels and he lost the following matches, coming nowhere near to the mastery he had demonstrated earlier.

The city this chess tournament was held in: Philadelphia; the name of this suspected cheater: Eugene Varshavsky.

In 2009, in a different intellectual sport of sudoku, two established solvers from past years and a complete unknown, who was solving his qualifying round puzzles under a hooded sweatshirt, made the finals of the Sudoku National Championship. As competitors were (unfortunately) allowed to wear headphones to listen to music and could have electronic devices such as ipods as timers on their desks, the opportunity for something unknown to be hidden under this "hoodie" such as a camera/transceiver that would allow a person outside of the room to use a computer solver to relay a solution back to a competitor, was great. While much drama occurred in the finals between the two established solvers, it did not go unnoticed by some (ok, me, but not just me) that the "unknown", who was now forced to wear sound-shielding headphones over otherwise bare ears and under much more careful watch to eliminate potential advantages, performed well below the standard of any solver who would have been capable of being on stage at the time.

The city this sudoku tournament was held in: Philadelphia; the name of this suspected cheater: Eugene Varshavsky.

Only in Hollywood. Except it happened.

I first noticed this solver after I had finished Round 3 of the tournament. I had already turned in my paper, which did not matter for the competition as I had qualified for the Finals in Round 1, when I turned to look at each of the finishers that followed. Well, the second place finisher who handed in shortly after me was dressed in a black sweatshirt, hood up and fully covering his hair and a lot of his head, with a nametag reading "Eugene" that was handwritten indicating he was a walk-in contestant who had not preregistered. Given his attire, unfamiliarity, and the fact "Eugene" left the room so soon after he turned in his paper, my Snyder-sense was tingling. Still, I chalked it up to possibly being nerves at having an unknown facing me on stage at the time.

I next observed Eugene much later as he came to the front of the room after being announced as the round 3 winner in the advanced division. He was not speaking to anyone - instead having a phone to his ear the whole time - and while I did congratulate him and shake his hand, he did not seem interested in much conversation with me. Again, fully explainable for other reasons - who would want to be intimidated by a world champion? - although I tend to offer friendly advice to solvers for how to deal with the whiteboard format since it is a big change from standard solving. I lost sight of him during the Beginner and Intermediate finals and frankly had my mind on other things as I stepped on stage to begin my own final puzzle.

The results of my attempt at this puzzle are now well reported: I raced through the final puzzle but by going too fast ended up making a transposition error in the last few digits I placed leading to my turning in an incorrect grid. While my errors were unknown to me and the judges for a couple minutes, when I finally stood up and looked back I got a quick bulge in my throat as I saw two sixes in the 5th row and saw for myself that my fate was sealed. So, instead of congratulating Tammy McLeod on finishing 2nd as she completed her puzzle in seven and a half minutes, I was the first to tell her she was the champion. The organizers would learn this fact from me too, which is unfortunate. Regardless, the rules of the tournament state that a second place finisher who is clean within twenty minutes would trump my boneheaded error, so I was concerned about the state of the third finalist's grid because he had stopped, similar to an apparent error in the first beginner final, when a finalist seemed to me to have been better off continuing solving as another solver had turned in an unfinished board with notes instead of givens.

At this time, in this advanced puzzle, with a thousand dollars extra on the line, Eugene also stopped solving as the round would be over and he would get the third place prize money. But I was not correctly finished, and the rules would allow him to continue for the full twenty minutes to try for a correct grid and in this confusion organizers were trying to figure out if it would be fair to give him more time (I would quickly have countered that he had seen two basically completed grids in the interim as he was standing near us when I was explaining to Tammy my problems, check the video). But I did take a chance to peek at his board to see if he had a decent claim to finishing second with more time and was beyond shocked to see that there were very very few numbers written in. He also had absolutely no notes or other markings as would be typical of every other advanced solver I have met in the US and overseas who could have qualified as a solver on stage.

While there are many assumptions made about sudoku, such as that the puzzle is originally from Japan, or that computers create the best puzzles, these assumptions are incorrect. Yes, computers create most of the available puzzles, but the best sudoku challenges, including those used in this tournament in the past, are hand-crafted and all the memorable hand-crafted ones like this final puzzle or Wei-Hwa's "Q" puzzle will have very tight solving paths with very specific sticking points that slow down a solver. Signatures of the designer's thought process, such as the type of sticking point, where it happens in the grid, if the same kind of sticking point is used multiple places, ..., are often a sign that can be used to tell if a puzzle is at least partially hand- versus completely computer-crafted.

A tight solution path also means that almost all solvers going logically through it without guessing will place numbers in a similar order and get stuck at similar/identical spots. On this puzzle, that path starts with placing at least a dozen digits in very quick succession - all of the 9s and all of the 3s and possibly a couple others - before hitting a stopping point where two sets of locked triples in boxes 1 and 9 are identified to lead to further progress. The evens are the key to the puzzle, hinted in part by having none of the evens in box 5 where progress is impossible for a long time, but the big triple for me was the one in box 9 with just evens. After these nice breakthroughs on opposite corners of the grid (the symmetrical placement another sign of the designer's hand at work here), a race to the finish will result as all the remaining digits are relatively "easy" singles. In fact, the trail of these final digits should be somewhat narrow and I'd bet that Tammy ended close to where I ended but wrote 46 and 4 instead of 64 and 6. The point of this aside is that on a difficult, well-crafted sudoku, the top solvers will certainly follow a similar series of moves and be stuck in the same spots. Just as a grandmaster in chess could look at a game and analyze inconsistently strong or weak plays and smell something funny, a grandmaster in sudoku (no such rating exists, but I'll suggest I probably qualify for consideration) can analyze a board and see a huge inconsistency in the level of progress a solver at the advanced level would have after 8 minutes even given the large whiteboard format. Indeed, in many online sudoku communities, the order and speed with which a player enters his digits is a very strong consideration for making a claim that a solver is cheating with computer assistance when solving a puzzle. So, being stalled at one of the triple-identification stopping points in this final puzzle would have made sense if at least ten more digits were in Eugene's grid. Having some notes or other markings on the board that speed solvers use to help find the way through the stopping point would have made sense too. It would at least show he was trying. Having a basically empty board missing several of the "easy" placements after 8 minutes does not.

As I was working through a complex mixture of disappointment and disgust with myself at the time I first observed these facts, I did not bring up all of these concerns with the organizers immediately which leads to this letter. Its probably not my role as a competitor to make sure the competition is run fairly, but it doesn't take a Dr. Sudoku to diagnose something is not right here. I did mention afterwards, and certainly that evening to Nick Baxter, that I thought the "Eugene" under the hoodie was possibly not the same "Eugene" on stage as the ability of the two solvers was so different from expectation. I'd barely seen any of his face when he qualified given the hoodie over it, so it was hard to rule out my wild speculation of two competitors. I began referring to the person(s) as "Eugene" with quote marks and this got into my initial posting on the tournament. Thankfully, the curiousity of that construction led to a foreign friend in puzzles, Johan de Ruiter, to post that he tracked this suspicion further and found a link to the past story about questionable behavior at a chess tournament in the exact same city by a competitor with the exact same name. Not caught red-handed, but with enough questionable signs that something certainly was up.

These suspicions are therefore rather serious and require some investigation. It would certainly be helpful for the Inquirer's film and photography coverage to be reviewed for pictures of this competitor before the finals and on stage, and specifically that the state of his final puzzle after various amounts of time and certainly after eight minutes when he stopped be made publically viewable for the community of sudoku solvers to see as, just like an odd sequence of chess moves, it will be prima facie evidence of this claim I am staking some of my reputation on that this is not the kind of filled-in board a person who supposedly can finish 3 hard puzzles in 12 minutes on paper could have by any stretch of the imagination. Even with all my ranting about the difficulty and problems of the stage format, it simply is not possible. Rather, in my mind, cheating of some form must have occurred.

What to do?

As I do not believe Eugene fairly qualified for the stage, and therefore only two true sudoku solvers were in the finals, it unfortunately brings the championship of Tammy McLeod under a cloud of uncertainty which she does not deserve as she did beat me fairly after I certainly helped beat myself. As the rightful third finalist would have a very reasonable chance of finishing this puzzle within twenty minutes cleanly and beating me out for second place given the scoring method of the finals where accuracy counts first, if a decision to disqualify the current third place finisher is made, I believe the only fair decision is to declare us both runners-up to Tammy and split the difference in the prizes to each receive $3,500. I ask that the checks for both my prize and Eugene's be held until this suspicion is addressed, perhaps by establishing through various means in the chess community that this Eugene Varshavsky is the same person at the World Open. While I will reluctantly accept the $4,000 second place prize if no change in the results is made, I would much more gladly receive less money and see a deserving sudoku solver who should have been on stage claim the prize he'd won (yet still have to deal with wondering what could have been, short this malfeasance). I ask that we at least take some time to make sure the so-called "Cat in the Hat" did not strike back here this past weekend in Philadelphia.

I am sending this letter to the organizers of the tournament, and posting it for all to see on my blog (motris.livejournal.com), because I do not believe this matter should be dealt with entirely in private for the future health of the competitive sudoku community.

-Thomas Snyder