SudoCue Users
A forum for users of the SudoCue programs and the services of SudoCue.Net

Author Message
Novajlija
Rookie

Joined: 17 Nov 2007
Posts: 5

 Posted: Sun Nov 18, 2007 11:21 pm    Post subject: Is this valid? Let's use this code from another topic. .-----------------------.-----------------------.-----------------------. |7 6 1 |8 3 2 |4 9 5 | |4 9 8 |1 6 5 |2 37 37 | |3 5 2 |4 9 7 |6 1 8 | :-----------------------+-----------------------+-----------------------: |9 38 67 |63 4 1 |378 5 2 | |58 4 35 |2 7 9 |1 368 36 | |2 1 67 |36 5 8 |37 4 9 | :-----------------------+-----------------------+-----------------------: |1 37 9 |57 8 6 |35 2 4 | |568 2 35 |57 1 4 |9 3678 367 | |56 78 4 |9 2 3 |58 67 1 | '-----------------------'-----------------------'-----------------------' Let's suppose that number 5 is in R8C1 or R9C1 (they are in line) then R5C1=8, R4C7=8, R8C7=5. Then we can eliminate 5 from R9C1.
Ruud
Site Owner

Joined: 30 Dec 2005
Posts: 601

Posted: Sun Nov 18, 2007 11:55 pm    Post subject:

Hi Novajlija, welcome to the site.

 Quote: Let's suppose that number 5 is in R8C1 or R9C1 (they are in line) then R5C1=8, R4C7=8, R8C7=5. Then we can eliminate 5 from R9C1.

The last node in your chain should be R9C7=5.

The chain is a classic Forcing Chain, but you do not need to consider R8C1=5, just R9C1.

The grid:

 Code: .------------------.------------------.------------------. | 7     6     1    | 8     3     2    | 4     9     5    | | 4     9     8    | 1     6     5    | 2     37    37   | | 3     5     2    | 4     9     7    | 6     1     8    | :------------------+------------------+------------------: | 9     38    67   | 36    4     1    |*378   5     2    | |*58    4     35   | 2     7     9    | 1    *368   36   | | 2     1     67   | 36    5     8    | 37    4     9    | :------------------+------------------+------------------: | 1     37    9    | 57    8     6    | 35    2     4    | | 568   2     35   | 57    1     4    | 9     3678  367  | |-56    78    4    | 9     2     3    |*58    67    1    | '------------------'------------------'------------------'

This is a AIC that does the same elimination:

(5=8)r5c1-(8)r5c8=(8)r4c7-(8=5)r9c7 => r9c1<>5

It looks a bit like a W-Wing with the same pair at both ends.

Ruud
Novajlija
Rookie

Joined: 17 Nov 2007
Posts: 5

 Posted: Mon Nov 19, 2007 2:15 am    Post subject: Hi Ruud! I'm sorry, it's just oversight, it is R9C7=5. And about rule: for me is easier to consider 2 or 3 cells in line (in the same box), at the same time, and see what is result. I need help because I'm not sure is this right way. Novajlija = Fresh Blood
Nouggie
Regular

Joined: 26 Feb 2007
Posts: 19
Location: Washington, DC

Posted: Wed Nov 21, 2007 3:21 am    Post subject:

 Quote: The chain is a classic Forcing Chain, but you do not need to consider R8C1=5, just R9C1.

Ruud's suggestion is good one since it simplifies the logical chain.

Also, consider the converse by assuming that r9c7=8, giving
(8=7)r9c2=(3)r7c2=(5)r8c3=>r9c1<>5
_________________
Nouggie
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
 All times are GMT Page 1 of 1

 Jump to: Select a forum SudoCue - the Website----------------Daily Sudoku Nightmare & ArchiveClueless SpecialsClueless ExplosionsWeekly AssassinsTexas Jigsaw KillersSudoku LiteX-FilesDaily WindokuDaily Jigsaw SudokuSolving Guide & GlossarySamurai ContestGeneral Website Comments Sudoku - the Community----------------Help Me! I'm stuck!Solving Techniques & TipsWebsitesSoftwarePuzzlesPublicationsOff-Topic SudoCue - the Software----------------SupportWishlistCommentsReleases
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum