WSC Zilina report part 2

So having got to bed sometime after midnight on the Friday, me and Mike (with whom I was sharing a room) roused ourselves at 7am. I am not what you would call a morning person – unless you extend that to (small hours of the) morning person – and so I was the last to join the rest of the UK team for breakfast at the hotel restaurant. My previous breakfasts in this part of world have generally involved sausages, bread and mustard (and occasionally beer) and the restaurant did not let me down here. Indeed it thoroughly improved upon the matter by providing baked beans, a rare treat outside of the UK! It was David I think that produced an interesting titbit of trivia that marmalade was going out of fashion with Britain’s youngsters. It is apparently our patriotic duty to keep this flagging industry afloat. I can only confess to being highly disappointed upon discovering there was none of Britain’s finest to ironically spread across the rather small croissants provided.

So onto the competition. Saturday’s puzzling was to commence at 9am and wouldn’t be finished until midnight – albeit with a few breaks around mealtimes – but which nevertheless represented a gruelling schedule.

Round A

So as things turned out in the general rankings, this was a fairly highly weighted round and if you wanted a top place you really needed to ace this round. Its format was solve as many puzzles as possible in two hours. There was a twist to this however – most of the variant sudoku towards the beginning of the round were linked to some classic sudoku puzzles towards the end of it, by virtue of a common square. Thus whilst a 4×4 “sudoku” with only a 2 and 4 given has rather more than one solution, with the information its twin puzzle provided narrowed things down a bit.

Actually, I believe this to be a really nice idea for a sudoku championship, however the execution was flawed in two ways: firstly it was implied by the instructions that the flow of information would be variant -> classic. This was not the case, and in some cases things even went both ways. Okay, so far, so mildly diabolically clever. The second flaw was that then a lot of the classic puzzles were computer generated in such a way that there wasn’t a pleasing and logically rewarding solution path so you were better off guessing to be quicker on most of them. The trouble here is that if you break one, you’ve probably then broken both puzzles which can lead to some pretty hefty write-offs, as Jason was to find out. As irony would have it, the two puzzles I broke on this round I hadn’t guessed on. C’est la vie.

Rounds B & C

I’ve paired up these two half hour rounds together, because already this Saturday report is getting a bit long. On the other hand it’ll give you a feeling as to just how gruelling a day it was! Round B involved three symbology puzzles – basically classic sudoku but instead with Mayan, Roman and LED digits respectively. The Roman and LED puzzles had a bit of interest in that given clues were not necessarily complete – so V might indicate anything from 4-8. My strategy here however was to transpose everything into familiar arabic digits and after solving rewrite in funny digits. This was fairly successful as two out of three successful solves meant I was to go through to an extra playoff round, which in turn might give me a go at the little final. What was the point of all this? God only knows.

Round C was a collection of four puzzles fitted together to look like a snowman. Why? God only knows.

Round D

This was called “world record”. This is stupid. You cannot possibly hope to have anything like a fair world record for sudoku. There is no way to standardise a puzzle for comparison, which indeed is something of the appeal of the puzzle! Anyhow, what is more stupid is to then provide the hardest puzzle to ever appear in competition for this one off. Scanraid rated a typical fiendish puzzle from The Times at around 125, and a superfiendish at 225. This insane puzzle from last year in Goa

described by Thomas Snyder as being turned up to 11 – in tribute to This Is Spinal Tap – could only manage a paltry 378.

This bad boy?

This scored 641. This is THE sudoku puzzle the devil would set you to solve to save your soul. Only if you placed a wrong digit, made by say a guess, Cerberus would be there ready to take three large bites from your arse cheeks. I have looked up what a “double-finned swordfish” is and one day I hope to solve this logically. In less than a week.

A Belgian named Vincent Bertrand made a very lucky guess early on and solved it in 3 minutes and 6 seconds. That time is just about as insane as the difficulty of the puzzle itself. As it turned out, Vincent is actually a top top solver anyhow, and the only possible thing you can take away from him in that a room of 130+ people guessing, one person was likely to get it quickly.

And having had our first introduction to the farcical puzzles, we adjourned for lunch. This entry has gotten a bit long so I’ll save the afternoon and evening for the next one. Things can only get weirder!

WSC Zilina report part 1

First things first. It’s probably possible to go on and on and on and on and on and on and on about the organisational flaws of the 4th World Sudoku Championship. On the other hand I am neither as prolific nor as eloquent a writer as Thomas Snyder so to go into as much depth again would be pretty fruitless from my point of view. Instead, I’ll go through my experiences in Zilina pretty much as-is, splitting things up into bitesize chunks.

The trip out to Zilina was pretty smooth. I set out from Coventry on Thursday afternoon, to meet up with Michael Collins, a fellow member of the UK “B”-team. His house is in London, and made for a convenient base to get to our 9.50am flight from Stansted to Bratislava. I was a little apprehensive of staying over with someone who I had only exchanged a few emails over, but ultimately both him and his wife were perfectly charming about my problem. In the morning, we drove to Stansted, and we were both a little confused as to why we hadn’t seen George Danker (the 3rd member of the UK B trio) and his girlfriend Sophie who was coming out to spectate. Nevertheless, just as Michael and I had taken our seats, George and Sophie entered the cabin, and we could reorder our priorities. Namely to get down to solving lots and lots of puzzles.

Once arrived in Bratislava, we met up with a chap called Stefan, a Slovakian participant who was there to help us with transfers. His English was pretty broken (although not as broken as my Slovakian!) but we got a bus from the airport to the railways station fairly easily – albeit if the route didn’t show us a particular picturesque view of the Slovakian capital. We grabbed some food and drink at the station, and another of the Slovaks helped us buy some tickets and put us on a train to Zilina. This train it turned out had a “party carriage”, where it seemed the proprietor of the restaurant car had had a few too many Friday afternoon drinks! We were informed that in Slovakia too, this was a rare sight.

Frankly, it’d be worth having a few of these party carriages on some of the soulless commuter services run by South West Trains. I digress.

We were driven to the Holiday Inn in Zilina, which thankfully (see later!) was actually only just round the corner. We soon met up with the rest of the UK delegation, which included UK puzzling superstar David McNeill (David, you get far too little recognition for your undoubted talents and I am going to do my best to champion you here!), two-time UK sudoku champion Nina Pell and Mike Colloby. These three made up the UK A-team, and together with non-participating Ariane Blok completed the UK contingent. The A team were being sponsored by Puzzler Media to go out, whereas us B-teamers were paying our own way. Nina and Mike had qualified via an online competition. David’s record at previous championships speaks for itself, regularly featuring in grand finals! It turned out that I was sharing a room with Mike. (Although as it happened I only had 13 and a half hours of sleep in that room over the 3 nights we were there!)

We had a couple of beers at the hotel bar, then discussed puzzler matters first as a team, and then with the Americans. They had only sent out one team this year, which looked as strong as ever – featuring Thomas Snyder, Wei-Hwa Huang and Jason Zuffranieri together with team captain Nick Baxter. I follow Thomas’ and Jason’s blogs fairly regularly, and all three of us are regular solvers at nikoli.com. Actually, all three of us have been puzzle champions at nikoli – the proof of which comes from the exclusive nikoli.com t-shirt, which I was weraing that evening. I particularly treasure my own as it not only shows that I have managed to beat Thomas, but also because I am less than likely to do so again. Anyhow it was good to put names to faces. Incidentally, that night I managed to identify (although didn’t have time to talk to) Hideako Jo as he had his nikoli t-shirt on as well. I suspect he doesn’t have to do much clothes shopping given the regularity with which he wins nikoli championships!

The rest of the evening was spent in a big conference room where tables had been laid out in preparation for a buffet style dinner, which was to be followed by some cheesy introductory presentation and the instructions. The tables were organised by countries, and joining us on our table was Times journalist Jack Malvern. I normally have a real dislike for any sort of journalist, but Jack is a genuinely top bloke, and as we were to find out later, the 4th best participant at the 2002 World Air Guitar Championships.

Anyhow, events this evening stretched out way beyond midnight – surprising given that solving was to begin at 9am the following morning, to start a monster day in which pens and pencils wouldn’t be put down until midnight. Much of the confusion lay in the instructions to the puzzles, some of which had been unclear before but after these instructions seemed to be no more enlightened. Perhaps a lot was lost in translation – most Slovak-English translations I’d seen up to that point didn’t really flow, I’m assuming there are some pretty major syntax differences between the two languages. Anyhow, what did become clear is that our host, Jan Farkas, was the spitting image of Borat. An omen of things to come, unfortunately…

Jigsaw Falling Into Place

A.K.A:

Tom Collyer does the Times Super Fiendish sudoku

(yes yes, I’m still keeping with my Radiohead song title for my titles.)

Ok lots of people at some point or another have been interested into how I do sudoku. In particular I am able to give a vague idea of what I do, but i seems to go over most people’s head. Possibly the most baffling thing about my solving technique is that (most of the time) I solve quickly without guessing – even on the harder puzzles.

Now I believe guessing on easier puzzles is stupid, and always slower, but on hard puzzles things get more interesting. At this point I’m going to assume those still reading know a little bit about sudoku and have come across advanced solving techniques – in particular the x-wing and the swordfish. There was a helpful page on The Times website but it seems to have gone. Oh well. Anyhow, most people think that these techniques are slow, clunky, require too much notation and are generally more bother than the time spent looking for them are worth. On the other hand the constructive logic (as opposed to contradictory associated with guessing) makes for a much more satisfying solve. And isn’t necessarily slow either!

Ok so the best way to illustrate this is through a quick walk-through. That means I’ll show some of my steps along the way but ideally you should go through it too. The puzzle in question is the Super-Fiendish published in The Times today (Friday 27th March 2009). It looks like this:



With most sudoku puzzles, there are always a few “gimme numbers” you can place without too much bother. Like this:



But then I come to a sticking point. Time to start looking for some weak subsets. What I mean by these are rows or columns or 3×3 boxes that are nearly filled out (i.e. have <5 numbers left to be filled in). There aren't very many boxes here, but the rows and columns look promoising. As it happens, I seem to naturally check columns before rows - and the ones that catch my eye here are 3, 4, 6 and 7. In particular, the gaps in 4 and 7 seem to line up very nicely. Sure enough, we spot the first x-wing with the 9's. Let's mark that in:



That doesn’t seem to give anything. So I continue on, scanning the rows in a similar fashion. Lo and behold I find another with the 8’s:



Well that’s all well and good, but they don’t obviously seem to be giving me any information. Clearly I’ve missed something…I’m very good at over looking obvious things, so I bet you can already see where! Ok a little bit further down the line things are looking more promising – in particular the x-wing with 8 wasn’t actually needed:



Now the x-wing with the 9’s comes into play. Observe it gives us the 9 in the bottom left box:



This essentially breaks the puzzle. I’m a little slow to finish it off from that point – but if you can complete a difficult level sudoku then there shouldn’t really be any problems finishing it off:

EDIT: Just noticed I’ve made a trademark transposition error (again!!!) in this image. The 6/7 in the middle box should be reversed!



The time I recorded there was just over 5 minutes. Actually I reckon with a bit more sharpness on my part (slow day obviously – the point at which the puzzle was effectively broken was just before 3 minutes and even then there was a bit of faffing around) I could knock a minute off that time. Swordfish are sometimes a little trickier to spot but the principles remain the same.

Anyhow, I captured the whole thing as a video if the pictures don’t tell you everything. You can find it here: http://www.youtube.com/watch?v=pE4Iu5lwkyo

David M: I hope this highlights things a little better. Please let me know what you think!

2 + 2 = 5

After noticing that some rather cunning spam had gotten round the anti-spam filter (a question which asked what the colour of a red t-shirt was) to comment on one of my posts – I’ve changed the question. And this is for the better. Now if you wish to leave a comment, you must demonstrate you have a basic grasp of GCSE maths. If you don’t have such a grasp, I probably didn’t want to hear your stupid opinion anyway.

It’s interesting to note I’ll do literally anything before I start packing….

Edit: Perhaps It’s a teeny weeny bit harsh to discriminate against mathematical ignoramuses. So in keeping with the Christmas spirit, please note that this entry’s title (I’ve just noticed) provides the most brilliant cryptic hint for those who are “differently intelligent” as to what you need to answer my little poser.

Saved for a rainy day

So I decided today (and yesterday) were as good days as any to sit down and have a crack at the puzzles from this year’s world sudoku championships, held during the Easter break in Goa. I’m sure a few readers are familiar with how I was excluded from the team, so I suppose I had a point to prove. Going against me was the fact I’d not really prepared for (or ever seen) some of the variants, but going with me was some arrogance – especially given my recent victory in the nikoli puzzle championships , over a very strong field which included the two time world champion Thomas Snyder.

For the World Championships, all you need to do is complete seven gruelling rounds against the clock; five with lots of clever sudoku variants, and two with classic puzzles everyone knows and loves. All seven rounds contribute to the main contribution, and in addition the two classic rounds contribute to a classic competition.

The upshot of it all having wasted several hours of my life on a competition that’d long been and gone? I’d have been 55 points (perhaps 1 or 2 puzzles over the course of the 7 rounds) off the final playoffs in the main competition in 12th place, and 1 place off the playoffs for the classic competition (5th). Not quite as good as the undoubted star of UK puzzling, David McNeil, but I feel in sudoku at least I’m closing the gap. I suppose there’s always next year.

In a comment in one of my earlier rants, Lucy asked if I was bitter much? Being in a more diplomatic mood, I’ll refrain from commenting!