## Killer sudoku rules insanity

For fans of Killer Sudoku, Samurai Sudoku and other variants

### Killer sudoku rules insanity

OK, two cut'n'pastes in case the URLs go away or change:

Within each dotted-line "shape", a digit CAN be repeated if the normal row, column and 3x3 box rules are not broken. - sudoku for Sep 16

www.timesonline.co.uk/article/0,,18209-1781670,00.html

Within each dotted-line "shape", a digit CANNOT be repeated if the normal row, column and 3x3 box rules are not broken. - sudoku for Sep 15

www.timesonline.co.uk/article/0,,18209-1780248,00.html

Apart from the fact that the second is nonsense - you can repeat a digit as long as you break the normal rules - what on EARTH are the Times's puzzle people playing at?
jfm

Posts: 3
Joined: 16 September 2005

I think I'll stick to the assumption that digits are not repeated within the dotted enclosures. It hasn't failed me so far.
possum

Posts: 86
Joined: 05 April 2005

I used to believe that they couldn't be repeated in the dotted enclosures but mysteriously mucked up a few even when i was being carefull so now i believe they can be repeated.

That second quote was funny
Pi

Posts: 389
Joined: 27 May 2005

I don't think there is any ambiguity. Yes, The Times has messed up at least three times now in attempting to state, clarify and reclarify the rule situation, but each time it is reasonably clear what they were TRYING (and failing) to say.

Killer sudokus are just ordinary sudokus, with one additional constraint, namely that certain irregular groups of boxes have to sum to a given total. Nobody ever said anything about a further constraint that you cannot repeat digits within those dotted blocks (provided the ordinary rules of sudoku are not violated), so why make that assumption?

One more thing, can we agree on a stardard term of reference for the "irregular shapes enclosed by dotted lines" because I'm tired of typing "irregular shapes enclosed by dotted lines" every time! The words "boxes" and "blocks" are likely to cause confusion with sudoku 3x3 boxes, so maybe we could call them "regions" or something? Any ideas?
zebedeezbd

Posts: 60
Joined: 14 September 2005

zebedeezbd wrote:Killer sudokus are just ordinary sudokus, with one additional constraint, namely that certain irregular groups of boxes have to sum to a given total. Nobody ever said anything about a further constraint that you cannot repeat digits within those dotted blocks (provided the ordinary rules of sudoku are not violated), so why make that assumption?

...apart from the occasion when the Times stated that 'if the printed number is 6, the only combination possible is 1, 2 and 3.' (The Times, 31 August, 2005)
possum

Posts: 86
Joined: 05 April 2005

In an effort to homogenise our terms, I quite liked a post I read yesterday wherein the "irregular thingummys" were denoted as 'cages'.

Works for me.
Karyobin

Posts: 396
Joined: 18 June 2005

From the Times Online, sometime next week:

"Within each dotted-line “shape”, a digit CAN or CANNOT be repeated -- or possibly some *third* option."

"Also, one of the great things about Killer Su Doku is that they start with all 81 cells empty -- or they don't."

------------------------------

"Cages" is nice, as dotted lines visually imply bars and is absolutely unambiguous -- so it won't be suitable for publication in the TIMES. "Fields" work as well, as in a spreadsheet field that holds might contain a sum.

------------------------------

When solving puzzles in magazines published in languages other than English, often the best part of solving the puzzles is infering the rules, adding inductive reasoning to what would normally only require deductive reasoning. The TIMES bungling of this rule only hints at this. It'd be great if the next type of puzzle they start to publish includes NO RULES AT ALL, no explanation whatsoever, just a sample puzzle and it's solution. That's really all one needs to figure out Sudoku, or Killer. Sudoku with Diagonals would trip people up once or twice. It's be great not to really be able to nail down the complete rule set for several days or more
tso

Posts: 798
Joined: 22 June 2005

zebedeezbd wrote:I don't think there is any ambiguity. Yes, The Times has messed up at least three times now in attempting to state, clarify and reclarify the rule situation, but each time it is reasonably clear what they were TRYING (and failing) to say.

Killer sudokus are just ordinary sudokus, with one additional constraint, namely that certain irregular groups of boxes have to sum to a given total. Nobody ever said anything about a further constraint that you cannot repeat digits within those dotted blocks (provided the ordinary rules of sudoku are not violated), so why make that assumption?

I think that's what the debate is about: the Times first said that 1-2-3 was the only valid triplet for a region/cage of 6 - which implies that repetition is not allowed, since otherwise 1-4-1 is sometimes valid. They then said that repetition is allowed, and their last attempt was to change the word CAN to CANNOT in the rules, resulting in the nonsensical rule I mentioned above (and then change it back again) - but I'm not sure how one could argue that that wasn't intended to reverse the rule.

Either way, so far there hasn't been a puzzle involving duplicates in a cage (as far as I know), and so to me, so far, forcing one to consider the possibility of duplication and therefore consider multiple options which disappear if one assumes no duplication, is a daft restriction amounting to a speed-bump and nothing more.

One could also argue that we're all applying too much logic to the rules - but then, this is a logic puzzle!
jfm

Posts: 3
Joined: 16 September 2005

I Hope that sometime the toimes will tell us once and for all what the rules are for killer sudoku, if not then they are stupid and we should all agree on rules here.

I see no reason why we shouldn't be able to repeat a number inside a region and will play that way
Pi

Posts: 389
Joined: 27 May 2005

Pi wrote:I see no reason why we shouldn't be able to repeat a number inside a region and will play that way

Nelson saw no ships, either. ;-)
Karyobin

Posts: 396
Joined: 18 June 2005

Note that the rules have changed again today. It is not very elegantly written but digits now cannot be repeated in a dotted-line shape.

Now we can devote our attantion to getting them to stop filling in numbers !
Bigtone53

Posts: 413
Joined: 19 September 2005

Bigtone53 wrote:Note that the rules have changed again today. It is not very elegantly written but digits now cannot be repeated in a dotted-line shape.

I wonder what will or won't be allowed tomorrow. Perhaps we'll be allowed two 9s in the same row provided at least one of them is in a column that doesn't include a 4?
zebedeezbd

Posts: 60
Joined: 14 September 2005

That's just silly.
Karyobin

Posts: 396
Joined: 18 June 2005

Karyobin wrote:That's just silly.

My point precisely! The Times has been very silly indeed in some of the things they have done and said of late.
zebedeezbd

Posts: 60
Joined: 14 September 2005

Bigtone53 wrote:Note that the rules have changed again today. It is not very elegantly written but digits now cannot be repeated in a dotted-line shape.
!

No, it implies that we can as long as we do break the conventional sudoku rules
Pi

Posts: 389
Joined: 27 May 2005

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