in yesterday's tough the 45 rule is not necessary to get the 1 in r3c6,

there is a 15 in five cells in the top right box, this must take up 12345, therefore the remaining four cells can only be 5678, since two of the cells must add up to 15 then this is either 59 or 78, hence the remaining two boxes (part of the 16 summation extending in to the top center box) must be either 59 or 78 (ie 15) thus r3c6 = 1

there is a 15 in five cells in the top right box, this must take up 12345, therefore the remaining four cells can only be 5678, since two of the cells must add up to 15 then this is either 59 or 78, hence the remaining two boxes (part of the 16 summation extending in to the top center box) must be either 59 or 78 (ie 15) thus r3c6 = 1

- zaphod
**Posts:**7**Joined:**01 September 2005

The next step is to then go an fill in the pairs of cells that total 15, in each case the cells can contain only 6789, likewise do the pairs that sum to 14 with 5689. You should then find that r3 contains 4 cells with 6789, these numbers can then be eliminated from other cells in r3 yielding r3c1 = 5.

Does this logic make sense?

Does this logic make sense?

- zaphod
**Posts:**7**Joined:**01 September 2005

zundevil wrote:I don't think that's a stipulation, tso. They're sudoku puzzles (i.e. no duplicate digits in any row/column/box), and they've got additive rules. That it.

Without the additional stipulation that no digit may repeat within a single numbered area, many, if not most, of the puzzles will have mulitple solutions. They hint at this rule in their introductory article, but they didn't state it explicitly:

Quoting from their introduction (bolds are mine):

"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"

Without the missing stipulation, the part in bold would not be true. Three joined squares with the sum of 6 could be 1-4-1. Three joined squares totaling 24 could be 9-6-9.

- Code: Select all
`. . . | . . . | . . .`

. . 1 | . . . | . . .

. . 4 | 1 . . | . . .

------+-------+------

. . . | . . . | . . .

. . . | . . . | . . .

. . . | . . 9 | . . .

------+-------+------

. . . | . . 6 | 9 . .

. . . | . . . | . . .

. . . | . . . | . . .

See: http://forum.enjoysudoku.com/viewtopic.php?t=995&start=15

- tso
**Posts:**798**Joined:**22 June 2005

zundevil wrote:Lastly -- and please chime in with your own comments here -- I think this awesome new way to do Sudoku is going to go the way of the dodo. There just seem to be *too much information* to make them nearly as challenging as the traditional ones.

This variation has been in Japanese magazines for many years, but it is not one of the more common (popular) variations. I think they can be made substantially more difficult increasing the average number of cells within each numbered area. We probably won't see anything near the hardest possible puzzles until people like Argusj, Simes, Hanssen, etc adapt their software to these.

- tso
**Posts:**798**Joined:**22 June 2005

zaphod wrote:There is no reason why numbers cannot be repeated within the sum boxes so long as there is no conflict with traditional sudoku rules.

BTW did anyone else require an X-wing (the 7 in r2c2, r2c3, r4c2, r4c3) to solve the tricky puzzle yesterday... Maybe the 45 summation rule would have prevented this i don't know. I have never done the times sudoku before (the hardest guardian ones never require x-wings to complete the puzzle), so i was little surprised... i'm about to start the tough now

Then explain this statement from the Times introduction to the puzzle:

"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. "

Why not 1-4-1 and 9-6-9?

The person writing and/or editing the article didn't fully understand the rules.

- tso
**Posts:**798**Joined:**22 June 2005

Maybe there is a mistake in the article, not that unlikely given that the times makes the same spelling mistake every day on the sudoku page

"Tips and computer programme www.sudoku.com" should surely read

Tips and computer program www.sudoku.com

"Tips and computer programme www.sudoku.com" should surely read

Tips and computer program www.sudoku.com

- zaphod
**Posts:**7**Joined:**01 September 2005

Just how sure are you about this rule tso? Have you got puzzles from the same people in different publications where the rules are more fully explained? I ask because, like you say, just from reading instructions and solving puzzles inThe Times, it's frustratingly ambiguous. The statement you refer to certainly implies this is a rule, but it does no more than that. And then, on one hand, none of the seven puzzles I've seen solved (all but the one on Wednesday's front cover) from The Times have had a number twice in the same enclosure, but on the other hand, equally none of the puzzles have required you to assume this in order to solve it, and therefore none of them would have had multiple solutions if you don't assume this rule. So you see, it's infuriatingly impossible for us to decide one way or the other.

- PaulIQ164
**Posts:**533**Joined:**16 July 2005

I've asked for clarification on the timesonline sudoku page - I'll report back when a response is put there.

www.timesonline.co.uk/sudoku

www.timesonline.co.uk/sudoku

- silvercar
**Posts:**24**Joined:**05 July 2005

tso wrote:zundevil wrote:I don't think that's a stipulation, tso. They're sudoku puzzles (i.e. no duplicate digits in any row/column/box), and they've got additive rules. That it.

Without the additional stipulation that no digit may repeat within a single numbered area, many, if not most, of the puzzles will have mulitple solutions. They hint at this rule in their introductory article, but they didn't state it explicitly:

I'm not sure the criticism is fair, or that the alleged ambiguity exists. The Times explanation begins

"The normal rules of Su Doku apply BUT there are no clue numbers. Instead the cells joined by dotted lines must be filled with the numbers 1 to 9 that add up to the printed top left-hand figure." (my italics).

The definite article is significant: it does not imply any old numbers, possibly used more than once.

- roger888
**Posts:**19**Joined:**27 June 2005

PaulIQ164 wrote:Just how sure are you about this rule tso? Have you got puzzles from the same people in different publications where the rules are more fully explained? I ask because, like you say, just from reading instructions and solving puzzles inThe Times, it's frustratingly ambiguous. The statement you refer to certainly implies this is a rule, but it does no more than that. And then, on one hand, none of the seven puzzles I've seen solved (all but the one on Wednesday's front cover) from The Times have had a number twice in the same enclosure, but on the other hand, equally none of the puzzles have required you to assume this in order to solve it, and therefore none of them would have had multiple solutions if you don't assume this rule. So you see, it's infuriatingly impossible for us to decide one way or the other.

I can prove nothing, as all my logic in this case is inductive, not deductive.

I do not know if the puzzle I posted August 22 was created by the same source, but it would be *highly* unlikely that different Japanese sources used slightly different rules for what appear to be identical puzzles.

Though I've been solving mainly Sudoku recently, over the years, I've solved literally 100's of different types of graphic logic puzzles from a variety of on and offline sources, many of which are Japanese (see here and here for example -- I'm not one of those people who use the word "literally" when they really mean "figuratively".) I do not speak Japanese. Sometimes, deciphering the rules to the puzzle is a greater challenge -- and I don't always get it right at first. Though Nikoli usually gives pretty good graphic examples from which I can infer the rules without knowing the language, often I have to look at the solutions as well to be sure. The fact that in NONE of the solutions are there duplicate digits within a single numbered area is very unlikely -- but not impossible -- to be a coincidence.

- tso
**Posts:**798**Joined:**22 June 2005