All entries for January 2010

January 29, 2010

Friday Puzzles #29

Ok, so here’s part one of my mini-crusade to provide a more enjoyable alternative to those who can’t have a go at the UK WSC qualifiers. And indeed to those who have done or will do them. Puzzler have bastardised the name of diagonal sudoku, and instead call it “X-Factor”. In my opinion this sounds really quite stupid, but there we go, I’m not a marketeer.

This is the first time I’ve written a sudoku puzzle introducing the diagonal constraint. I think It turned out quite nicely, and should make a good warm-up for the coming harder diagonal puzzle.

Incidentally, the remaining puzzles for this initial section will be a harder diagonal, two classic sudoku puzzles, and a killer. Bearing in mind I think the Puzzler killer generator is actually quite good, I’m going to have my work cut out with that, but those are worries for another time. For now, enjoy!

#034 Diagonal Sudoku – rated medium

All puzzles © Tom Collyer 2009-10

January 25, 2010

Friday Puzzles to return!

After a little break over Christmas and the new year, I’m pleased to announce that my Friday Puzzles will be returning!

The return has been inspired by two things. The first of which is a sudoku competition, created by Thomas Snyder. There is an awful lot that you could say about Thomas Snyder, but I think the thing that strikes me about him most is that if he doesn’t like something, he may well moan vociferously about it, but he’ll also offer his own take on how things could be fixed. His sudoku cup was, in part, his personal reaction to the fiasco in Zilina.

The second source of inspiration is the upcoming UK WSC qualifier, which I’d like to point my interested British readers to here. I’ve not entered yet; I’ll leave that until the last week as I don’t like waiting for ages and ages to see whether I’ve screwed up or not but in my experience the advertising for it is absolutely piss poor and generally not in the interests of picking the strongest possible UK team.

On the other hand, that’s a criticism I’ve laid at these online qualifiers the past couple of years anyway. Part of that criticism lies at the actual test itself – its collection of vanilla variants still hot from the Puzzler Media generator, coupled with a couple of Vladimir Portugalov’s safer variants, doesn’t really make for the best indicator of the sort of skill set required to excel at WSC on-site solving of more and zestier variants. Especially when the test is online only! There hasn’t been a UK WSC qualifier that hasn’t involved technical hitches either on the part of solvers, or on the part of Puzzler not being sure about cheats yet. Additionally, last year in Zilina, the two people who had qualified by virtue of their test performance were the 5th and 6th best performing of the 6 people representing the UK. Just sayin’.

On a personal note, I’ll add that in most countries where there is an offline national sudoku competition, the winner qualifies for the national team. That sounds pretty reasonable to me…

Anyhow, in response to this, I thought I’d like to improve upon their efforts. As such, in the coming weeks you can expect to see some of the variants you’d see on a UK WSC qualifier – so think a couple of classics, a couple of diagonals, a couple of odd/evens, a couple of killers – and then perhaps a couple Portugalov variants too. These will be better both in quality than the qualifier, and in principle because since there’s nothing at stake, there’s no point in cheating[*]. You (I couldn’t possibly; I’m natural partisan to this argument) might even contend that hypothetically, those who excel at my hand authored puzzles are better prepared for what will be thrown at them in Philadelphia than those who have learned the nuances of the generator.

Anyhow, even if you think all of the above is bollocks, then at least enjoy my puzzles, and I’ll be glad to have helped prepare those who intend to enter the UK qualifier in my own small little way.

[*] This implicitly challenges Puzzler’s assertion that there is no point in cheating simply because “standards are high”.

January 05, 2010

Legal Tender

A new year then, and a lifting of my previous convention of exclusively titling my entries with a Radiohead song title. It was nice whilst it lasted.

I’ve been up in Scotland recently, to see in the new year at Edinburgh’s Hogmanay, and I must say that I had a lot of fun doing things of questionable value to my health, all within the confines of a rather large street party. Amongst several things I’d like to talk about – such as how Edinburgh is one of the most aesthetically pleasing cities I’ve had the pleasure to visit, or how as a proud southerner it’s remarkable how quickly the novelty of snow wears off – what I’m going to settle here on is the money used north of the border. Funny money, if you will.

As everyone will doubtless be aware of, bank notes are basically glorified I.O.U. notes, issued by various banks. The initial idea being that rather than carrying around stacks of gold, you could carry around one of these notes, and then redeem them at your own convenience. That coinage does exactly the same thing and we could chase this wild goose right up the path of “What exactly is money, anyway?” I shall leave for now – instead I shall test the hypothesis that what makes bank notes work is the idea of legal tender. If someone is in your debt, and they give you something, and that something is legal tender then should you refuse to accept that something then you may not have that debt remain in force. Long story short, legal tender appears to make today’s [well perhaps yesterday’s given how most money today is electronic] currency work as it should.

In England, we have a central bank which is a lovely idea in which we can all have the utmost of confidence, and indeed dear reader, as you check the money in your wallet I’m sure the credit-worthiness of your debtor, the Bank of England, barely troubles the surface of your conscious mind. You might think that legal tender explains things here. And yet there is curious anomaly when it comes to Scotland. No bank notes are legal tender in Scotland! This curious state of affairs doubtlessly dates back to the time when both the Royal Bank of Scotland and the plain old Bank of Scotland enjoyed far better reputations than they do today, and our jolly McCousins up north could happily swap their glorified I.O.U.’s without the consent of us meddling Englishmen. And though times have changed, I doubt anyone has the stomach to push through any sort of legislation and so promissory notes issued by various Scottish banks, together with Bank of England notes, float around without ever needing to be accepted by anyone other than the bank in question. This system appears to work – perhaps legal tender is not all that it’s cracked up to be – however I would warn against getting into too much debt with angry Angus McArse in case he refuses your nice bank notes as repayment and instead will accept only deep-fried haggis.

Interestingly – this time I can speak for the entirety of the United Kingdom – when it comes to coins only the £1, £2 and the £5 variety are counted as legal tender; the smaller denominations have limits. This is presumably for the convenience of the creditor: should you wish to sell your lovely big house in the country, you are not going to want it paid for in a lorry load full of 10 pence pieces.

As I’m on the subject of convenience I shall conclude with the anecdote that ties this whimsy back together. Also whilst away in Edinburgh, I received an email reminding me that I have a book out of Warwick library coming up to its due date. Only by the time I read the email, that due date had passed and I had amassed a 20p fine. This, bearing in mind we are out of term time, the book is fairly obscure, and the fact you can only pay fines to the value of £1 or more online has certainly inconvenienced me. On the other hand, 20p is the exact limit of a debt that may be paid by coinage consisting entirely of one penny and two pence coins. I shall delight in imposing some entirely legal inconvenience of my own next Monday.


Welcome to the blog of current UKPA sudoku champion, two-time Times national sudoku champion and general logic puzzle fan Tom Collyer.

Home of the original Friday Puzzles, each Friday I publish a 100% original and handmade logic puzzle, inspired by the world-famous Nikoli company.

How to play:
AkariFillominoHashiHeyawakeHitoriKakuroLITSMasyuNumberlinkNurikabeRipple EffectShikakuSlitherlinkSudokuSuraromuYajilin.


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Latest comments

  • I like the appearance of the solution. :P Nice one. by Prasanna Seshadri on this entry
  • I think I've seen something vaguely similar in some of Palmer's puzzles as well. To be honest I've a… by on this entry
  • That's two puzzles in a row where I find something I had used before. I know, not plagiarism; just g… by Bram on this entry
  • Kota, that's not really true. I had made my puzzle before going to the WPC already. Also I don't hav… by Bram on this entry
  • About 20 minutes, after restarting from a mistaken conclusion. by Bryce Herdt on this entry

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