The New Sudoku Players' Forum

by **tommy** » Tue May 02, 2006 7:33 pm

Code: Select all: 94x 256 xx7 x53 847 9x2 72x 9xx 4x5 57x xxx 29x xx2 795 xxx x94 x2x 758 2x9 xxx 57x xx7 5x2 6x9 xx5 379 x2x

by **ravel** » Tue May 02, 2006 9:25 pm

For those, who could not paste it into their solver

Code: Select all: 9 4 . 2 5 6 . . 7 . 5 3 8 4 7 9 . 2 7 2 . 9 . . 4 . 5 5 7 . . . . 2 9 . . . 2 7 9 5 . . . . 9 4 . 2 . 7 5 8 2 . 9 . . . 5 7 . . . 7 5 . 2 6 . 9 . . 5 3 7 9 . 2 .

by **TKiel** » Tue May 02, 2006 9:29 pm

Tommy,

There is a naked pair in row 3 that excludes from all other cells in that row the two digits that make up the naked pair.

You also have several instances of 'box-line interaction' that would allow you to make many other exclusions.

If you are unfamiliar with these terms check out these links:

www.angusj.com/sudoku/hints.php (Refers to box-line interaction as locked candidates)

www.sadmansoftware.com/sudoku/techniques.htm

www.scanraid.com/BasicStrategies.htm

Tracy

by **Havard** » Tue May 02, 2006 9:35 pm

tommy wrote:
Code: Select all
94x 256 xx7 x53 847 9x2 72x 9xx 4x5 57x xxx 29x xx2 795 xxx x94 x2x 758 2x9 xxx 57x xx7 5x2 6x9 xx5 379 x2x

hm, it's quite a though one this little bugger... I'll assume you know basic moves like box-line interactions and locked sets, and just show you the "nasty" bits...

Code: Select all: Swordfish in columns: 1 7 8 9 4 18 | 2 5 6 | 138X 138X 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13 13 | 4 68 5 ------------------+-------------------+------------------ 5 7 16 | 146 1368 48 | 2 9 136 1368X 1368- 2 | 7 9 5 | 13X 134X 1346 136X 9 4 | 16 2 13 | 7 5 8 ------------------+-------------------+------------------ 2 138 9 | 146 168 48 | 5 7 13 1348X 138 7 | 5 18 2 | 6 1348X 9 1468 168 5 | 3 7 9 | 18 2 14 . . . | . . . | 3X 3X . . . 3 | . . . | . . . . . . | . 3 3 | . . . ---------+----------+--------- . . . | . 3 . | . . 3 3X 3- . | . . . | 3X 3X 3 3X . . | . . 3 | . . . ---------+----------+--------- . 3 . | . . . | . . 3 3X 3 . | . . . | . 3X . . . . | 3 . . | . . . Almost Locked Sets Chain: 9 4 18 | 2 5 6 | 138 138 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13#a 13 | 4 68 5 ---------------------+----------------------+--------------------- 5 7 16#d | 146 1368#a 48 | 2 9 136 1368 168#d 2 | 7 9 5 | 13 134 1346 136#c 9 4 | 16#b 2 13#c | 7 5 8 ---------------------+----------------------+--------------------- 2 138#e 9 | 146 168-1 48 | 5 7 13#e 148 138 7 | 5 18#a 2 | 6 1348 9 1468 168 5 | 3 7 9 | 18 2 14 Almost Locked Sets Chain: 9 4 18 | 2 5 6 | 138 138 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13#d 13#c | 4 68 5 ------------------+-------------------+------------------ 5 7 16#a | 146 1368 48 | 2 9 136 1368 168#a 2 | 7 9 5 | 13 134 1346 136#a 9 4 | 16 2 13#b | 7 5 8 ------------------+-------------------+------------------ 2 138 9 | 146 68 48 | 5 7 13 148 138-8 7 | 5 18#e 2 | 6 1348 9 1468 168 5 | 3 7 9 | 18 2 14 Almost Locked Sets Chain: 9 4 18#d | 2 5 6 | 138 138 7 16#f 5 3 | 8 4 7 | 9 16 2 7 2 68#e | 9 13 13 | 4 68 5 ---------------------+----------------------+--------------------- 5 7 16#d | 146 1368 48 | 2 9 136#c 1368 168 2 | 7 9 5 | 13 134 1346 136 9 4 | 16 2 13 | 7 5 8 ---------------------+----------------------+--------------------- 2 138 9 | 146 68 48 | 5 7 13#c 148-1 13#a 7 | 5 18#a 2 | 6 1348#a 9 1468 168 5 | 3 7 9 | 18 2 14#b Almost Locked Sets Chain: 9 4 18 | 2 5 6 | 138 138 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13 13 | 4 68 5 ---------------------+----------------------+--------------------- 5 7 16 | 146 1368 48 | 2 9 136 1368 168 2 | 7 9 5 | 13 134 1346 136 9 4 | 16 2 13 | 7 5 8 ---------------------+----------------------+--------------------- 2 138 9 | 146#c 68#c 48#c | 5 7 13-1 48 13#b 7 | 5 18#b 2 | 6 1348#a 9 1468 168 5 | 3 7 9 | 18#a 2 14#a

Enjoy!

Havard

by **ronk** » Tue May 02, 2006 10:10 pm

Hi tommy, Do you have the starting clues? TIA, Ron

by **Carcul** » Tue May 02, 2006 10:39 pm

Code: Select all: *-----------------------------------------------------------* | 9 4 18 | 2 5 6 | 138 138 7 | | 16 5 3 | 8 4 7 | 9 16 2 | | 7 2 68 | 9 13 13 | 4 68 5 | |-------------------+-------------------+-------------------| | 5 7 16 | 146 1368 48 | 2 9 136 | | 1368 1368 2 | 7 9 5 | 13 134 1346 | | 136 9 4 | 16 2 13 | 7 5 8 | |-------------------+-------------------+-------------------| | 2 138 9 | 146 168 48 | 5 7 13 | | 1348 138 7 | 5 18 2 | 6 1348 9 | | 1468 168 5 | 3 7 9 | 18 2 14 | *-----------------------------------------------------------*

1. [r5c8]=4|8=[r1c7|r1c8]-8-[r1c3]-1-[r4c3]-6-[r4c9]=6=[r5c9]=4=
[r5c8], => r5c8=4.

2. [r5c7]=3=[r4c9|r5c9]-3-[r7c9]-1-[r7c4|r7c5]=1=[r8c5]-1-[r3c5]=1=
[r3c6]-1-[r6c6]-3-[r6c1]=3=[r5c1]=8=[r9c1]-8-[r9c7]-1-[r5c7], =>
r5c7<>1 and the puzzle is solved.

Check this post for an explanation of the notation that I have used.

Carcul

by **ravel** » Wed May 03, 2006 8:50 am

Yet another solution:

Code: Select all: *-----------------------------------------------------------* | 9 4 18 | 2 5 6 | 138 138 7 | | 16 5 3 | 8 4 7 | 9 16 2 | | 7 2 68 | 9 13 13 | 4 68 5 | |-------------------+-------------------+-------------------| | 5 7 16 | 146 1368 48 | 2 9 136 | | 1368 -1368 2 | 7 9 5 | 13 134 +1346 | | 136 9 4 | 16 2 13 | 7 5 8 | |-------------------+-------------------+-------------------| | 2 #138 9 | 146 168 48 | 5 7 #13 | | 1348 138 7 | 5 18 2 | 6 1348 9 | | 1468 168 5 | 3 7 9 | 18 2 14 | *-----------------------------------------------------------*

An empty rectangle removes 3 from r5c2.

Then you have:
If r4c9=3:
r7c9=1,r8c8=3(r8c2<>3)
(r5c789<>3)r5c1=3,r5c2=8,r8c2=1
no 1 for box 8 left
=> r4c5=3

by **tommy** » Tue May 16, 2006 11:34 am

ronk wrote:Hi tommy, Do you have the starting clues? TIA, Ron

Hi Ronk,No I do not have the starting clues. I feel clueless sometimes. I am relatively new at this game and need some instruction on improving my techniques.

I am impressed by the number of responses I got from my post and plea for help.

I just got home from out of state and hope to make some sense of all these links, threads, etc.

Thank you again and I hope to hear from you again. It will be ok if you are too busy to help.

tom

by RW » Tue May 16, 2006 6:24 pm

tommy wrote:I am impressed by the number of responses I got from my post and plea for help.

And here's one more:

Code: Select all: *-----------------------------------------------------------* | 9 4 18 | 2 5 6 | 138 138 7 | | 16 5 3 | 8 4 7 | 9 16 2 | | 7 2 68 | 9 13 13 | 4 68 5 | |-------------------+-------------------+-------------------| | 5 7 16 | 146 1368 48 | 2 9 136 | | 1368 1368 2 | 7 9 5 | 13 134 1346 | | 136 9 4 | 16 2 13 | 7 5 8 | |-------------------+-------------------+-------------------| | 2 138 9 | 146 168 48 | 5 7 13 | | 1348 138 7 | 5 18 2 | 6 1348 9 | | 1468 168 5 | 3 7 9 | 18 2 14 | *-----------------------------------------------------------*

if r6c4<>6 => r4c456=468 => r4c9=3 => r7c9=1 => r7c456=468 => Double solution

=> r6c4=6

RW

[edit: oops, I should have finished the puzzle... this doesn't solve the puzzle, but helps a bit. Btw there's a UR in r15c78 that eliminates candidate 1 from r5c8.]

by **daj95376** » Wed May 17, 2006 12:11 am

Havard,

I don't think there's a Swordfish in columns {1,7,8} because there are four rows {1,5,6,8} containing 3's. It's my understanding that the candidate value must be limited to a cross-hatch of three rows and three columns only.

Code: Select all: Swordfish in columns: 1 7 8 9 4 18 | 2 5 6 | 138X 138X 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13 13 | 4 68 5 ------------------+-------------------+------------------ 5 7 16 | 146 1368 48 | 2 9 136 1368X 1368- 2 | 7 9 5 | 13X 134X 1346 136X 9 4 | 16 2 13 | 7 5 8 ------------------+-------------------+------------------ 2 138 9 | 146 168 48 | 5 7 13 1348X 138 7 | 5 18 2 | 6 1348X 9 1468 168 5 | 3 7 9 | 18 2 14 . . . | . . . | 3X 3X . . . 3 | . . . | . . . . . . | . 3 3 | . . . ---------+----------+--------- . . . | . 3 . | . . 3 3X 3- . | . . . | 3X 3X 3 3X . . | . . 3 | . . . ---------+----------+--------- . 3 . | . . . | . . 3 3X 3 . | . . . | . 3X . . . . | 3 . . | . . .

by **Havard** » Wed May 17, 2006 12:16 am

daj95376 wrote:Havard,

I don't think there's a Swordfish in columns {1,7,8} because there are four rows {1,5,6,8} containing 3's. It's my understanding that the candidate value must be limited to a cross-hatch of three rows and three columns only.

Code: Select all
Swordfish in columns: 1 7 8 9 4 18 | 2 5 6 | 138X 138X 7 16 5 3 | 8 4 7 | 9 16 2 7 2 68 | 9 13 13 | 4 68 5 ------------------+-------------------+------------------ 5 7 16 | 146 1368 48 | 2 9 136 1368X 1368- 2 | 7 9 5 | 13X 134X 1346 136X 9 4 | 16 2 13 | 7 5 8 ------------------+-------------------+------------------ 2 138 9 | 146 168 48 | 5 7 13 1348X 138 7 | 5 18 2 | 6 1348X 9 1468 168 5 | 3 7 9 | 18 2 14 . . . | . . . | 3X 3X . . . 3 | . . . | . . . . . . | . 3 3 | . . . ---------+----------+--------- . . . | . 3 . | . . 3 3X 3- . | . . . | 3X 3X 3 3X . . | . . 3 | . . . ---------+----------+--------- . 3 . | . . . | . . 3 3X 3 . | . . . | . 3X . . . . | 3 . . | . . .

I guess I should have been more spesific. That creature is called a finned swordfish!

Havard

by **ronk** » Wed May 17, 2006 10:59 am

daj95376, just to clarify what ...

Havard wrote:
Code: Select all
. . . | . . . | 3X 3X . . . 3 | . . . | . . . . . . | . 3 3 | . . . ---------+----------+--------- . . . | . 3 . | . . 3 3X 3- . | . . . | 3X 3X 3 3# . . | . . 3 | . . . ---------+----------+--------- . 3 . | . . . | . . 3 3X 3 . | . . . | . 3X . . . . | 3 . . | . . .

I guess I should have been more spesific. That creature is called a finned swordfish!

Either the fin cell (r6c1) holds a 3 or it doesn't. If it does, the 3 in r5c2 is eliminated. If it doesn't, the standard swordfish in c178 eliminates other 3s in r158. Either way ... r5c2 cannot hold a 3.

The New Sudoku Players' Forum

please help me finish without quessing.

please help me finish without quessing.

Re: please help me finish without quessing.

A Possible Solution