Friday 26 October 2012

Friday Puzzles #180

So next up in the WPC series.  Colliding battleships is a type from the twisted puzzle rounds, which I enjoyed the most not because I actually solved it in time, but indeed because I didn't and instead drew a giant shark's fin in the grid for the last 30 seconds of the round.  The twist on this puzzle is kind of interesting because it removes a lot of constraints you use whilst solving.  Unfortunately it makes it very hard to set a uniquely solving puzzle.  Sadly for you, dearest reader, it means that I've lost patience trying to put together something of more substance this evening and so this is really only instructional fare.  I am especially appreciative of the skill displayed in constructing the more meaty WPC puzzle!

Rules: (as taken from the WPC instructions)
Locate the position of the fleet shown next to the grid.  The ships cannot touch each other, not even diagonally.  Numbers outside the grid indicate how many cells contain parts of ships in the corresponding row/column.
Note: Only two ships of different size are touching each other!

    #215 Colliding Battleships – rated easy

All puzzles © Tom Collyer 2009-12.

Wednesday 24 October 2012

Kraljevica '12 day 4: World Puzzle Championship I

I was perhaps a touch late down to breakfast, but thankfully not feeling the worse for wear from the previous night.  Team UK were discussing dominoes strategies, led by James, and which mainly involved abusing uniqueness like a boss.  I sort of nodded my head along without contributing too much to the discussion.  Unfortunately I was in my own little world when it was mentioned that rather than the WPC desks being allocated individual names, only countries and teams.

As we all filed into the room, it was quickly apparent that Neil and James has nabbed the best two UK-A seats.  Perhaps this was for the best as those two were always going to clearly be beating both myself and Liane, but all the same after my positioning in the WSC, I can hardly say I was enamoured to be sat with Bram de Laat directly to my left, Ulrich Voigt directly to my right, Palmer Mebane a few seats back at 7 o’ clock and Hideaki Jo a few seats forward at 1 o’clock.  I will not complain in the slightest about having Michael Ley nearby - not because he isn’t a formidable puzzler too, because he most certainly is - but because before rounds he’d turn round and offer people some boiled sweets to help you going through the rounds.  I have made a note of this and I shall be trying something similar for future competitions.

WPC Round 1: Domino Hunt

So I don’t think I’ve described the bonus structure attached to various rounds throughout both competitions.  The idea was to have a relatively short round which the organisers anticipated people would finish.  If not enough people finished during this time, then a 5 minute extension would apply for everyone.  I think Ulrich did manage to finish in time, but I completely forgot about the extension and was guilty of rushing through the 10 point puzzle, as well of a couple of others.  So whilst I thought I had done reasonably well to have finished all but the last puzzle this round, it turned out that in my eagerness to abuse uniqueness I had made several mistakes.  Three in fact, scoring me 24/60 for the round.

Another short break, and then onto a longer round.  A nice two hour round!

WPC Round 2: Blackjack

This round was kind of cute, with lots of 21 themed puzzles.  In retrospect I think I probably got far too bogged down with the giant octopus puzzle, and only got 10 of the 21 puzzles out.  Moreover I made a silly mistake on the Zebra puzzle - a kind of paint by numbers puzzle which a priori had no connection to 21 but as you solved it revealed a giant pictogram of a certain two digit number.  Anyhow, 65/240 points is probably indicative that this is exactly the sort of round I’ll need to improve upon if I want to better my (so far) modest placings!

Onto lunch.  I was back to feeling dazed, and after finishing in the restaurant headed upstairs to the bar (for a lemonade!) and to get out my puzzle notepad.  I was still aiming to get my little killer puzzle completed and ready for publication on the blog for Friday, but the great thing about these championships is the fact you never seem to be alone for long.  Tiit wandered over and gave us some Estonian puzzle magazine.  Inevitably Jason materialised and before you knew it we were racing again.  I wanted a shot at him on a kakuro (unwise), and a killer (also unwise).  I think at this point Thomas - who was in the background somewhere blogging - had spotted a pattern, but I managed to pull things back to 2-1 with a good slitherlink solve.  I can’t remember the order of the other puzzles, but I think he then took easy as ABC, and I got the battleships and the hitori.  I’d like to think that I got the nurikabe to make things 4-3, but I honestly can’t remember.  I have the horrible feeling Jason probably shaded it.

Clearly I already had bigger things on my mind.  Like:

WPC Round 3: Twisted puzzles

This was basically a round of classic puzzles, where each of the puzzles had a solitary instance where the rules were bent slightly.  So think a kakuro with one cell left empty, or tents where one tree had two tens tied to it.  This round I spent a lot of time not getting the magnets out, and getting bogged down with the four winds with one lying clue, but all in all 48/120 wasn’t quite as disastrous as blackjack.

Still, no time to dwell on missed opportunities, the rounds kept a comin’!

WPC Round 4: Easy as ABC

Strangely enough, this featured no classic Easy as ABC puzzles, instead we a fun crossword variation, a cute snake variation and a somewhat clunky hex grid variation.  Three of each and half an hour to get things done.  Oh, except I don’t think any did.  Except maybe Ulrich (his third finished round of the day incidentally) and so we got the 5 minutes overtime again.  I managed all the crosswords and two of the three hexas, sadly breaking the third.  I get the feeling my time might better have been spent on the snakes, but 36/60 was at least better than half the points available, so not too bad.

Time for a coffee.  Get cup, press espresso button.  Press espresso button again.  Spoon in enough sugar to get a dentist twitching slightly.  Get some water so I wouldn’t dehydrate.  Take a trip to a toilet.  Have a bit of small talk with people sat around me, mainly Bram and Vasso.  Prepare for the next 90 minute round.

WPC Round 5: Black and White

A round with lots of shading!  I got 9 of 15 puzzles out, although as is always the way none of the really big hitters in the round.  Most frustratingly this included a really fiddly tapa puzzle worth 22 points which I just couldn’t tweak, despite probably spending the last half hour trying and failing to get a solution out.  I claimed at the time that I was going to boycott tapa forever and ever - or at least a few months?  Weeks!? - but I’m sad to report I accidentally did one on croco recently.  No mistakes though, so at least that’s something.  57/180 however is probably a score which undersells me.  Again!

That was that for the individual rounds, but as with the WSC there was a half hour break where the room was set up for the team round.  This second day of competition, and the temptation to go up to the bar and get a nice cool refreshing beer was greater than before, but again I managed to resist, instead guzzling down a bottle of coke.  Perhaps I should have had more of a discussion with Team UK regarding the team round, but I kind of hoped James had a bit of an intuition given his thoughts posted on the UKPA forums beforehand.  Anyhow, we got ourselves into position, right next to the German A team, ready for:

WPC Round 6: Marina

So this was just a giant optimisation puzzle where you had to place plastic boats on a massive grid with a marina drawn out.  Various bits of the marina had different (x5, x3 and x2) multipliers, and there were a few convoluted rules about making sure that every boat had enough space to individually get out.  I’d like to say we had a strategy, but what ended up happening was the four of us took a corner of the grid, filled it up, and then rotated round to start tweaking.  At the time, we had no idea how successful this would be, but I think it worked out OK because despite accidentally placing too many of one particularly type of ship, thus losing easy points, we finished slap bang in the middle of the pack.  Of course we were only to find this out much later; instead we left the competition hall feeling pleased with the detour from churning out puzzle after puzzle.  An optimisation problem of course needs a good sense of what is going on, but there is necessarily a large intuitive component to getting a good solution out.  Interestingly enough, AJ had a different perspective on things.  Since you had no idea how well you had done as a team, there was a lingering dissatisfaction for him.  On reflection I can certainly see how you’d think this.

For dinner, I think other members of team UK were efficient enough to grab a big enough table that we could all squeeze around, which was nice as typically we had to split our rather large contingent over at least two tables.  As per normal dinner lingered on before everyone slowly migrated upstairs to the bar.

Initially things were a bit quiet, Fred and Bastien were chatting away, and Bram was probably sat there with his laptop putting up something for his blog.  I think he’s unrivalled for the amount of practice material he prepared, and I took the chance to catch up with what Thomas and Palmer had had to say on their particular little patches of the internet.  I certainly got a chuckle reading about Thomas sleeping with socks on his hands to stop the insects biting in the night; thankfully I had no such problems with my room.

I had also managed to get the little killer for my blog, and set about formatting it up.  As a professional graphic designer who knows nothing other than Illustrator I got to introduce him to Inkscape, of which I am very fond of, even if you have to run it under X11 on a mac.  Neil was naturally curious and so I got him to have a go at solving it, challenging him to get it done before I came to giving it a rating.  My dearest readers are invited to look back at that particular blog post to see whether he managed this challenge.  Fred and Bastien came over and made lots of useful and helpful and particularly delightful comments about symmetry, and much laughter was had at my expense!

Inevitably the bar session reverted into another puzzling showdown, again with Yuka’s excitingly presented sudoku magazine.  I should mention this was doubly novel for me as the magazine read from back to front!  After the previous night’s experience, I think Bram had rightly been concerned about joining forces with me again, and so instead formed a formidable trio with Jason and Tiit.  My trio, presumably motivated by a desire to laugh at me some more, featured my two favourite francophones.

Having used up the actual relays in the magazine the previous evening, we had to improvise somewhat, and ending up flicking to the back of the magazine.  Or front of the magazine I should say!  We found a two page spread of classic sudoku, ominously labelled with numbers ranging from 40 to 70.  What could these numbers mean!?  Anyhow, the format this time round would be 3 individual solves, 3 paired solves and then 1 with all three of us.

Getting stuck into the puzzles it quickly became apparent that the “mysterious” numbers could only be time targets.  I was up first and so thankfully had the easiest puzzle.  I actually made steady progress through this one, and let out a half-delighted “x-wing” as I managed to get the puzzle up.  My opposite number, Tiit looked up and asked firstly whether I had guessed, and secondly whether I had made a mistake.  I’m not sure he was  totally convinced by either of my denials!  Anyhow, after these puzzles the difficulty ramped up and everyone was using things like forcing chains and other solving techniques that should never see the light of day in competition.  Beyond x-wings, swordfish, xy-wings and simple colouring I’m afraid I’m not much use here - although the x-wing I spotted that led to no digit being placed was met with more (!) laughter from Fred.  I think he was especially appreciative of the help I could offer after he’d cracked the hard part of the puzzle where I would point at the grid and say “two.”

At some point it reached about half 1 in the morning, when Bram said that he’d regretfully have to pull out of our self-inflicted sudoku painfest as he (rightfully!) argued he didn’t want to compromise his 2nd day of competition.  Unless you count the excellent spectator sport of endless mockery directed at me by Fred and Bastien, I can safely say that he missed nothing!

Friday 19 October 2012

Friday Puzzles #179

So I've not really been able to pick a stand-out puzzle from the WPC like I could from the WSC.  I think what I'm going to do is release my favourite puzzle from various rounds and then maybe do a vote or something for your favourite in a few weeks time.  What I can tell you now is that I'm not going to do a dominoes puzzle, and unfortunately the puzzle I have in mind from round 2 has uniqueness issues, so you might have to wait until tomorrow until this gets published.  Hey - at least I got this disclaimer out on Friday.  Ugh.  Sorry!

UPDATE: I suppose I should add fair warning.  I tested this puzzle after 5 pints of Guinness last night, and I was very pleased with the logic that I thought made this solve uniquely.  I'm not so confident that this has a unique solution now, but I have no time to re solve it at this moment in time as apparently I'm wanted on television.  Given the issues I had with uniqueness making the bloody thing I'll not be surprised if someone finds a second solution here...

Rules: (as taken from the WPC instructions)
Place some tiles (of size 1x2 squares) in the grid, with numbers 1 and 2 each.  Tiles can be rotated but they cannot touch each other, not even diagonally.  Numbers outside the grid indicate the sum of all the numbers in the corresponding row/column.

    #214 2-1 Tiles – rated hard
All puzzles © Tom Collyer 2009-12.

Thursday 18 October 2012

Kraljevica '12 day 3: Excursion

The rest of day 3 was to provide a respite from the intense day of competition on day 2, which I certainly welcomed.  We were to be bussed away on a series of coaches to have a tour of the nearby city of Rijeka.  Waiting for these buses to arrive, I found myself in a brief moment of solitude sitting in the sun, and was joined by multiple WPC champion Wei-Hwa Huang.  Wei-Hwa is something of an oasis of calm within the US ranks, and I can only imagine how much of a pleasure solving the sudoku team rounds must have been for them with him directing the solve.  I asked how things were within the team ranks and how his own preparation was going, and found his reply to be quite telling.  Being on a team with the twin peaks of intensity provided by Palmer and Thomas apparently rubs off on even the most phlegmatic of characters, and so whilst Wei-Hwa stated he was just here to have some fun, he also mentioned he felt a little pressure to get some preparation in just to keep his head above water.  We were briefly chatting about the various travel opportunities puzzling was providing us, when fate dealt a cruelly ironic blow, and Wei-Hwa pointed out that if I wanted to go on the excursion I should probably head over to the buses.

So I was conscious of the fact the tour guide on the bus was saying various things on the bus as we headed towards Rijeka, but as with last year I took the opportunity to whip out my notebook and get working on the little killer I was intending to publish on the Friday.  I’d had a good idea, but couldn’t quite flesh it out by the time we arrived.

There we were, probably in excess of 100 puzzlers on tour let loose in the city, which to be honest was quite a surreal experience.  We were loosely being guided by the tour guides who’d been on the buses through the landmarks of Rijeka, which firstly included some sort of a church which I presume from wikipedia was Svetište Majke Božje Trsatske.  This loosely translates as being a “sanctuary,” but the main church bit was far from tranquil as the puzzling horde invaded!

The next stop off was some sort of fort, with a good view of the city below but which was otherwise fairly unremarkable.  That said, it did provide the first starting of the German Michael Drinking Unit (Ley and Smit), who seemed to be sat down in every bar with a cigarette and a refreshing beverage to hand at every turn during this excursion!  After we’d all had our fill of the castle, we trudged back to the buses to be taken down the hill and into the city proper.  On the walking tour, I can’t claim to have been paying much attention, although I was quite amused when a fairly unimpressive arch was pointed out as having once thought to have been a triumphal arch (I can’t for the life of me think why when you compared this to say, Rome, Paris, or Barcelona for example...) and instead turned out to be an entrance to some Roman building.

Anyhow, I latched on to a group with the Americans and Prasanna.  Being hugely cultured individuals, we decided to pay our respects to another of Rijeka’s magnificent arches - or should I say golden arches?  Anyhow, I was of the opinion that it was quite hot and humid and it was high time to follow the lead of GMDU and find a nice place to sit down.  Whilst apparently Prasanna and Thomas were talking about the slim likelihood of me being able to roll out of the gutter and back onto the bus, later, I was having a good chat with Nick Baxter, Rodders and Will Shortz about far more important things: namely sport!  Not that I care all that much, but apparently the Ryder cup was still something of a sore point for Nick and Will.

As much as I’d have like to have lingered in the bar doing my best to fulfil Thomas’ prediction, we soon had to move back to the bus, to be taken to some hotel for a dinner, and the WSC closing ceremony.  Entering the hotel, we offered a choice of aperitifs (oh how I love mystery Eastern Europea spirits!) before I broke ranks with team UK and plonked myself down on what was to turn out to be the American table.  I should probably state that I’m all for team unity and the rest of it, but these championships come round once a year and I think it’s a waste not to go a mingling with everyone else - and it’s not as if for most of the breakfast/lunches/dinners at Uvala Scott weren’t being spent with the team.  Instead I found myself speaking about “math” with Josh Zucker (JZ mk II!), JZ (mk I) and Anderson Wang.  I think I managed to amuse them with my “talent” for factorising quadratic equations with integral coefficients by eye rather than an anything more pedagogical, but I was definitely pleased to employ some geometric group theory to help confirm an answer to a fiendish triangle counting puzzle Wei-Hwa had come up with.

The dinner drifted pleasantly by with the wine flowing and more puzzles appearing on the dinner table, before it was time for the prize giving ceremony.  The Poles were obviously jubilant with Jan’s victory, and had seemingly managed to acquire several of the aperitif bottles in preparation for a long night!

After the prize giving I thought it was probably best to say hello to Mike Colloby and Alan O’Donnell, who were the last of team UK to arrive having only just been driven in with Stefano.  Alan was participating on the WPC B team, whereas Mike had the important job of presenting the British bid to host the world championships in 2014.  I also managed to congratulate George Wang on the Chinese success.  Rereading an article he penned for I think the 2007 WPF newsletter it is remarkable to think how far puzzling in China has come in the last few years!

Being a little tipsy at this point, I stumbled onto a different bus to be driven back to Uvala Scott, which turned out to be a good thing as on it were both the victorious Poles, as well as a few of the Japanese.  Moreover, there was still plenty of the bottles of spirits going around, and Kuba took itself upon him to conduct the drinking on the bus, walking up and down the aisle inviting everyone to swig with him from the bottle.  Outstanding!  Needless to say, this wasn’t an opportunity the legendary Tetsuya Nishio was going to pass up on, and there were shouts of “Kampai” and “Na zdrowie” all round.

The remaining business of the day was to be held in the bar back at Uvala Scott.  Yuka Noyama had very kindly given me a copy of a rather exciting looking Japanese sudoku magazine - which was in stark contrast to anything you might find on sale here in Britain - and I had suggested that Jason go find so we could set up some racing!  In retrospect, it should probably not have surprised me as to how bad I was going to be, but I thought a relay team of myself, Gaurav Korde and Bram de Laat should have easily had the beating of Jason and the Greeks (perhaps they were Argonauts?).  The early running was good as I finished the first puzzle a minute or two ahead of Jason; I have a picture of him still working to prove this, ;-)  but things were to level out as some drunken idiot kept making mistakes.

The only thing for it was to grab another beer, and chat with the Poles for a bit before belatedly realising there was like some important competition or something due to be starting in the morning, and that we should probably attempt to get some sleep.  Or something!

Wednesday 17 October 2012

Kraljevica '12 day 3: WSC play-offs

When I woke up I think it’s fair to say that, despite not knowing the overall results, I was fairly confident I hadn’t hit the heights of the top 8 and so would almost certainly not be participating in the WSC play-offs.  Now, an awful lot has been said about the format of the play-offs this year, but I am going to save any more detailed analysis to a future series of blog posts discussing the matter where I hope to engage the community at large.  Instead, I’m going to focus on describing them from a spectator’s point of view.

Kraljevica '12 day 2: World Sudoku Championship

For previous championships I have the feeling that arriving before about 10 in the evening gives you sufficient time to settle down, because I hadn’t quite woken up on the morning of competition with the usual butterflies in my stomach.  I’d woken up at 8 and was showered and changed and down in the restaurant a half hour later, and still nothing.  I can’t say I was particularly enamoured by the breakfast either.  The whole cold breakfast meats with bread and mustard wasn’t particularly what I wanted so in the end I plumped for some cereal.  It didn’t seem to make a difference between the yellow supposed corn version or the brown supposed chocolate version - both ended up being fairly cardboard-y.  Nothing very liberal sprinklings of sugar couldn’t fix!

Sunday 14 October 2012

Kraljevica '12 day 1: Arrival

So given some of the troubles that my fellow competitors had in getting to the Uvala Scott resort near Kraljevica, Croatia, I’m not going to linger too much on the blissfully pleasant time I had in Trieste waiting for the bus to transfer me.  The sun was shining, it was warm, we had had a gorgeous lunch up in the hills outside Trieste before coming down to enjoy a lingering coffee on the Piazza Unità.  Paradise!  There was momentary concern about whether the bus was actually going to show up at 5pm at the railway station, but after meeting up with a few other equally concerned puzzlers, it was quickly established the bus was at the nearby coach station instead.

Our route to Croatia had to backtrack to Trieste airport, where we picked up a few more puzzlers.  It was great to meet up with some of the Japanese contingent, Yuhei, Kota and Yuka, who had been been making a big detour through much of Italy as part of their journey as well as the Greeks - formidably led as ever by Vasso - and my old drinking buddy Jason of the US.  One of the great things about these championships is the chance to meet up with so many different people from different countries, but it is always nice to speak with someone who as English as their mother tongue.

Our merry busload didn’t even notice the Italy-Slovenia border, but at the Slovenia-Croatia border a chap came on board to inspect our passports.  I briefly wondered what he thought of our particular medley, but was more thankful that my middle names were remarkable for there being two of them rather than what they actually are.  I was also amused by the proliferation of weather symbols dispersed across the new British passport.  There was one further stop at some services, which seemed a little unnecessary given we were about half an hour away from the place, but it did give us a chance to stretch our legs and for Jason to purchase a bag of what I assume were sweets but were entitled something very close to the word scrotum.  Interestingly enough this was the last I heard of this particular bag of treats...

We finally arrived, turning a corner with a sign pointing towards a “sport disco” (my guess was rugby) and Uvala Scott.  Disembarking, we formed a nice orderly queue to receive our room keys.  As it was dark I couldn’t really get a feel for the place, but as I handed over my passport I noticed that this hotel’s key was actually a physical key, and on walking up to my room in the dark that this hotel was more like a concrete version of Butlins.  Oh well.  It’s not like the trip advisor reviews had been glowing, and quite frankly I end up spending as little time as possible in my room at these championships as is possible anyway.

I wandered down to the main bit of the resort, with the bar and the restaurant and the competition hall.  In the competition hall, the Q&A session for the sudoku championship was about to get underway, but I was pretty hungry at this stage and instead chose to grab some food from the restaurant.  As in previous years, the catering model was an industrial scale buffet - albeit one sorely lacking in both quantity and quality of cakes - which meant that the food wasn’t going to be particularly great, but at that particular moment in time I didn’t really care.  I passed over the complimentary glass of bubbly, which apparently couldn’t leave the restaurant, but bought a bottle of beer, which could, and headed over to the Q&A session.

I met up with the UK team, which at this point of proceedings consisted of the official A team, featuring Neil Zussman, Roderick “Rodders” Grafton and Michael Collins, as well as the two ladies, Liane Robinson and Emma McCaughan, who were unofficial B-team participants.  Liane pointed out that with spectacular timing I had arrived just as the questions had finished.  Not that that really mattered, I only had one minor query about whether a diagonal constraint was going to be present on the little killer (more on this later!) but otherwise the instructions seemed to be fairly self-explanatory.

We stayed and chatted on for a bit longer before deciding it was probably a good idea to head off to bed.  And I’d like to say that was that for the first day, but this would be to do discredit to a magnificent thunder storm that manifested at roughly midnight.  I’ve never experienced a thunder storm by the sea before, but I can tell you it’s quite an experience!  The lightning reflects off the sea and lights up the sky for miles and miles, and the thunder booms down, rumbling across across the water until it hits the shore and physically shakes the room.  Needless to say sleep wasn’t going to happen until Zeus, Thor, Perun et al had had their fun, and so whilst they were busy with all of that, I decided to have some fun of my own.  With a puzzle book.  ;-)

Friday 12 October 2012

Friday Puzzles #178

So I'm back from Croatia, dearest reader, and as promised I've made a homage to one of my favourite puzzles from the WPC.  It is a somewhat curious fact that this puzzle type didn't feature in any of the competition rounds, but was instead introduced to me after hours in the bar by my good friends, the merry Polish puzzlers.  Whilst the actual competition is one of the most important thing at these championships, it is my humble opinion that the socialising afterwards with fellow puzzlers is equally as important.  Anyhow, as is always the way with these things, broadly sweeping statements were made by all concerned and before I knew it I was committed to broadcast this wonderful innovation to the world.

Now as I'm sure all my dearest readers now, detuned radio is very much a blog that promotes family fun, but I fear that this week we will be pushing things to the limit.  However I'd like to think that if nothing else, I am a man of my word, so here goes.  Please bear in mind I've had to give a few aspects of this puzzle a slightly different description!

Place some 1x3-cell rectangles of either orientation, and some circles (contained in a single cell) into the grid.  Rectangles may not touch rectangles, and cells containing circles may not touch cells containing circles, even at a single point.  Each rectangle must orthogonally touch 2 circles, to form a T pentomino, and each T pentomino touches a further circle at its base, so that there is a set of several disjoint hexominoes of the same type in the grid.

(N.B. I'm not sure if there is a standard labelling of hexomino types by letters given there are 35 of them, but the one I have in mind is definitely the one that looks most like a capital T.  With apologies to my illustrious e-mail correspondent for the previous ambiguity!)

Numbers outside the grid indicate how many cells in the corresponding row or column are used by rectangles.

If things aren't beginning to become clear, just be thankful this type probably isn't going to feature as a manipulative team round any time soon.  Ahem.  Enjoy!
    #213 Bit of a T's – rated easy
All puzzles © Tom Collyer 2009-12.

P.S.  I'll put up a puzzle which did feature in competition next week!
P.P.S.  Expect some lengthy championship reportage soon!

Friday 5 October 2012

Friday Puzzles #177

Greetings from Croatia, where it's great to be in the company of the international puzzling fraternity.  Some things never change though, and again I find myself on a Thursday night formatting up a puzzle ready for publication.  The WSC has been and gone and washed me up in 28th place, which I'm satisfied with even if I was aiming to break into the top 20.  There's always next year!  Team UK finished the team competition in 12th, which is modest progress on last years 14th, and all the more creditable in the absence of David McN, who sadly had too many commitments to make it out this year.  I look forward to trying to get one over him at next year's event!

Congratulations are due to Jan M of Poland for taking his 3rd title, and to the Japanese all-star team for running away with the team title.

Anyhow, onto puzzling matters.  My idea was to take my favourite puzzles from both the WSC and the WPC and provide my own humble homage.  I thought a lot of the puzzles from the WSC were if not disappointing, then no better than mediocre, many seemed to have come from straight out the generator.  From an aesthetic point of view, it was a little disappointing to observe a distinct lack of symmetry in the play-off puzzles.  The one difference was a little killer puzzle which was a lot of fun to solve.  Perhaps at this stage I should mention that that puzzle, as well the one below, does not require there to be different digits on the main diagonals of the grid.  Perhaps I should also mention that I've got Neil Z sat across the table test solving, and he hasn't managed to crack it yet.  On that basis, this gets a "hard."  Enjoy!
    #212 Little Killer Sudoku – rated hard

All puzzles © Tom Collyer 2009-12.

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