## Killer Sudoku

For fans of Killer Sudoku, Samurai Sudoku and other variants
You don't NEED confirmation. Solve the puzzle without applying this rule. As long as you have a logical basis for each placement, you'll either find the solution OR come to a standstill that can only be bypassed by assuming no duplicates in one enclosure. You'll be able to construct multiple solutions, only one of which follows the "unconfirmed" rule. Since we are *given* that all puzzles have unique solutions -- you will have both solved the puzzle, and PROVED THAT THE RULE IS REQUIRED for a unique solution.
tso

Posts: 798
Joined: 22 June 2005

It is very difficult to know if "you have come to a standstill" or just have missed something along the way. That's why it would be helpful to know if the rule exists or not.

Logic says you don't publish a puzzle without giving out all the rules, so you would expect it not to be a rule rather than a rule be missing!
silvercar

Posts: 24
Joined: 05 July 2005

silvercar wrote:It is very difficult to know if "you have come to a standstill" or just have missed something along the way. That's why it would be helpful to know if the rule exists or not.

Take my word for it! Solve the puzzle as if it is a rule -- if you get the solution, time after time after time, then where is the problem? So far, no one can come up with a SINGLE EXAMPLE contradicting this rule.

I've checked a stack of Japanese puzzle magazines -- where the puzzle originated -- and they all follow the rule AND have multiple solutions if you IGNORE the rule.

silvercar wrote:Logic says you don't publish a puzzle without giving out all the rules, so you would expect it not to be a rule rather than a rule be missing!

Logic has nothing to do with an oversite. Newspapers make mistakes all the time. Take a look at the bottom of the three puzzles here: http://www.timesonline.co.uk/article/0,,18209-1760208,00.html

It says "Copywrite Puzzles by Pappocom". Pappocom does not supply the Killer puzzle.

They've been notified of the mistake -- yet they keep printing it.

Much of the backstory written and repeated in many newspapers is woefully inaccurate -- stuff about Euler and Latin squares (Euler did not invent Latin squares, they predate him by many centuries -- and nothing he did invent lead to Sudoko. He did invent the Latin-Graeco square, which has *nothing* to do with Sudoku -- other than they are both derived from Latin Squares.), the "fact" that crosswords are impossible or difficult in the Japanese language (They're actually very popular in Japan. The reporters are confusing Japan with China.), etc.

Again, I invite you to read exactly what they've given for the rules here (bolds are mine):

http://www.timesonline.co.uk/article/0,,7-1757275_3,00.html

The joined squares must be filled with the numbers 1 to 9 that add up to the printed top left-hand figure.

Hints to solve Killer are hidden in the joined squares where only one combination of numbers is possible. In the case of two joined squares, if the printed number is 3, it should be 1 and 2 that go into the squares; if the number is 17, the combination should be 8 and 9. Likewise, in the case of three joined squares, if the printed number is 6, the only combination possible is 1, 2 and 3; if the number is 24, 7, 8 and 9. It is best to start by solving the joined squares with the lower-value printed numbers and then gradually move on to those with larger printed numbers. Killer Su Doku also has a time set by its compiler. See if you can beat the clock.

First, there is no other plausible explanation for the sentence in bold other than duplicates are not allowed in an enclosure. If they were, 1-4-1 and 9-6-9 would be perfectly acceptable. This sentence is not giving an arbitrary rule, it's giving an example of the general rule.

Second "It is best to start by solving the joined squares with lower-value ..."? Uh, that's ridiculous. It's just as likely that the best place to start is by examining cells with the highest numbers. What this tells us is that the person writing this doesn't know what s/he's talking about, and may very well not have understood the rules that were given.

Further, if it turns out that the puzzles don't follow the general rule of no repeat digits in enclosures, but DO follow a pair of arbitrary 1-2-3 not 1-4-1 and 7-8-9 not 6-9-6 rules -- the I sure as heck won't want to solve another.

I suppose I could scan the rules from one of the magazines and post them here in case one of the readers can speak Japanese. Can one of you speak Japanese?
tso

Posts: 798
Joined: 22 June 2005

I can count quite a long way, and I can describe all sorts of painful acts from karate, aikido and kendo. So I can speak a bit. Problem is, I can't read a thing.
Karyobin

Posts: 396
Joined: 18 June 2005

I have managed to do 4 of the killer su dokus in Wednesday 31st August's paper, but can't seem to get going on the Tough one. I've only managed to get 6 numbers so far (1,7 and 6 in column 6 and 7,8 and 9 in column 5).

Please can anyone give me a hint?
possum

Posts: 86
Joined: 05 April 2005

Look at what cells in row 3 can only have 6,7,8 or 9 in them due to them being part of a two cell pair adding to 15. What does that leave as possibilities for another cell in row 3 ?

Paul
Enigma

Posts: 53
Joined: 14 June 2005

Thank you, Paul; that has enabled me to make a bit more progress.
possum

Posts: 86
Joined: 05 April 2005

Hmmmmm, well, personally, I think "Killer" Su Dokus kill through sheer boredom - or possibly the term refers to my desire to murder whomever cut out the third "real" Su Doku from the Times each day and replaced it with one of these yawn-inducers!

Adding up and subtracting little numbers is about as exciting as doing the accounts... to which these puzzles bear a strong resemblance IMHO.

They seem to test maths skills first, and logic as a poor second, and I would never voluntarily do maths for amusement.

With so many Su Doku variants around (see elsewhere on these boards for examples), it's a pity The Times chose this one.

Just a personal opinion! If you enjoy them, good luck to you!

The Druid
The Druid

Posts: 33
Joined: 22 April 2005

Karyobin wrote:I can count quite a long way, and I can describe all sorts of painful acts from karate, aikido and kendo. So I can speak a bit. Problem is, I can't read a thing.

Oss..
boaz

Posts: 26
Joined: 31 August 2005

Hoory i beat the clock!
Pi

Posts: 389
Joined: 27 May 2005

If anyone wants an extra Killer to do the one on the front page of that T2 with the 5 in has a perfectly good one to finish, alas, without a difficulty rating or time advice.
Disko

Posts: 1
Joined: 05 September 2005

already have, i would never mis the chance of a sudoku
Pi

Posts: 389
Joined: 27 May 2005

The Druid wrote:Hmmmmm, well, personally, I think "Killer" Su Dokus kill through sheer boredom - or possibly the term refers to my desire to murder whomever cut out the third "real" Su Doku from the Times each day and replaced it with one of these yawn-inducers!

Adding up and subtracting little numbers is about as exciting as doing the accounts... to which these puzzles bear a strong resemblance IMHO.

They seem to test maths skills first, and logic as a poor second, and I would never voluntarily do maths for amusement.

With so many Su Doku variants around (see elsewhere on these boards for examples), it's a pity The Times chose this one.

Just a personal opinion! If you enjoy them, good luck to you!

The Druid

Yeah, I agree. I suppose the advantage they see in using this variant is that it is the most different from the original. There are several variants that are far more common and/or popular in the Japanese puzzle world than this one, though the standard Cross Sums puzzles are nearly as popular as Sudoku.
tso

Posts: 798
Joined: 22 June 2005

I wasn't going to respond to The Druid, because as was quite rightly stated, it was an opinion. But seeing as tso has come in on one side I have to say that, even though I luurrve sudoku, as one of those (few?) people whose primary approach to anything is mathematical, I especially like the Killers.

'Wordy' people have always had crosswords for their amusement and the likes of tso have always had puzzle publications of varying degrees of difficulty, but us mathematical types have always been hard-pushed for anything taxing. Why is it that the only maths-based puzzles I can access on a daily basis are vapid tosh, worded along the lines of 'If Kenny the Capybara *eeks* fourteen more times per hour than Gervaise the Giraffe...etc...'?

What is the source of this underlying aversion to using maths recreationally? Why does one frequently hear uttered such absurdities as "Don't ask me about maths, I'm terrible at it!" Have you ever heard anyone say that about their English skills? Damn right you haven't, because there seems to be a certain degree of shame attached to the latter, whereas the former is trooped out at every opportunity, almost as a talisman affirming 'normality'.

Don't get me wrong, I've read The Druid's and tso's comments, and they aren't implying anything of the kind on their own part. What bothers me is the fact that, frequently, as soon as maths creeps into someone's life uninvited, they rail against it as if the very thought of doing it 'for amusement' is an alien concept. Why should this be so? And of course, far more importantly, what about those of us who do do maths for amusement? Are we destined always to sit quietly on the wings, accepting our lot as perceived freaks whilst the rest of the 'normals' giggle about and denigrate our mindsets? Maybe I should go to a crossword website and harass them?

I understand that 'pure' sudoku (such as are featured on this site) have no maths involved in the process of their solution, and I certainly don't wish to evangelise about my own inclinations. But seeing as these 'new' kinds have turned up, and seeing as Wayne hasn't yet shut this thread down for being off topic, as seeing as I bloody enjoy doing them: give The Times a break; give me and all the freaks a break and be happy that amid all the fun we're having, a new facet has turned up that includes even more people.

P.S. Sorry, can't stand Cross-sum types, very little logic in my experience and far too much T & E.

P.P.S. I realise they (Killers) may not be new tso, but I don't have your encyclopaedic knowledge of puzzle-evolution. Sorry for any unintentional mistakes.

P.P.P.S. Why does 'seeing' have two 'e's' and 'being' doesn't?
Karyobin

Posts: 396
Joined: 18 June 2005

The really nice thing about this site is that we can disagree so totally, and express opposing perspectives with passion and eloquence... while still remaining polite and respectful to each other.

Long may it continue.

The Druid
The Druid

Posts: 33
Joined: 22 April 2005

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