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Free Press December 30, 2011

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keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Fri Dec 30, 2011 2:09 pm Post subject: Free Press December 30, 2011

Not yet started ...

Code:

Puzzle: FP123011
+-------+-------+-------+
| . . . | 5 4 9 | . 8 . |
| . 3 6 | . . . | . 9 . |
| . . . | . . . | . . . |
+-------+-------+-------+
| . 5 9 | 8 . . | . . . |
| . . 1 | . . 7 | 2 . . |
| . . . | . . 2 | 4 5 . |
+-------+-------+-------+
| . . . | . . . | . . . |
| 4 9 . | . . . | 6 7 . |
| . 2 . | 9 . 3 | . . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Happy New Year!

Keith

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Fri Dec 30, 2011 3:30 pm Post subject:

Code:

+-----------------+-----------------+---------------+
| 17 17 2 | 5 4 9 | 3 8 6 |
| 5 3 6 | 7 2 8 | 1 9 4 |
| 9 8 4 | 36 6(13) 6(1) | 5 2 7 |
+-----------------+-----------------+---------------+
| 2 5 9 | 8 6(3) 4 | 7 136 (13) |
| 8 4 1 | 36 5 7 | 2 36 9 |
| 367 67 37 | 1 9 2 | 4 5 8 |
+-----------------+-----------------+---------------+
| 1367 167 3578 | 4 1678 156 | 9 13 2 |
| 4 9 358 | 2 18 (15) | 6 7 13(5) |
| 167 2 57 | 9 167 3 | 8 4 -1(5) |
+-----------------+-----------------+---------------+

(1=3)r4c9-3r4c5=(3-1)r3c5=1r3c6-(1=5)r8c6-5r8c9=5r9c9 : -1r9c9; stte

Happy New Year !

JC

PS : the following Wing is simpler but harder fo find or to justify IMHO ...
8r7c3=(8-7)r7c5=7r9c5-(7=5)r9c3 : -5r7c3; stte

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Fri Dec 30, 2011 5:54 pm Post subject:

JC Van Hay wrote:

Code:

Happy New Year !

JC

PS : the following Wing is simpler but harder fo find or to justify IMHO ...
8r7c3=(8-7)r7c5=7r9c5-(7=5)r9c3 : -5r7c3; stte

Thanks JC, you saved me the trouble of constructing a grid. Looking at the 17 UR in boxes 17, either r7c12=6 or r7c1=3. Either 6 forces r8c9=3. Using this and r7c1 as pincers; r7c8<>3.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Fri Dec 30, 2011 5:57 pm Post subject:

JC Van Hay wrote:

the following Wing is simpler but harder to find or to justify IMHO ... 8r7c3=(8-7)r7c5=7r9c5-(7=5)r9c3 : -5r7c3; stte

I consider it a beautiful and somewhat common pattern.

Code:

+------------------------------------------------+
| . . . | . / . | . . . |
| . . . | . / . | . . . |
| . . . | . / . | . . . |
|---------------+----------------+---------------|
| . . . | . / . | . . . |
| . . . | . / . | . . . |
| . . . | . / . | . . . |
|---------------+----------------+---------------|
| / / 8+X | / 78+Y / | / / / |
| . . . | . / . | . . . |
| # # # | . 7+Z . | . . . |
+------------------------------------------------+

There's an ungrouped strong inference (SI) on <7> in [c5] and on <8> in [r7].

All that's needed is a bivalue cell in r9c123 (#) containing <7> and/or <8>.

If the bivalue cell contains <7>, then the companion candidate can be deleted from "X".

If the bivalue cell contains <8>, then the companion candidate can be deleted from "Z".

You get a loop with many eliminations if a (#) cell is <78>.

Then there's the ALS possibilities in [b7] that contain <7> (only) in r9c123.

Now, if I were to nominate something for harder to find and justify as a "wing", then I'd nominate:

Code:

(7=ALS=3)r789c3 - (3=UR=6)r17c12 - (6=ALS=7)r9c139 => r7c12<>7

arkietech

Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

Posted: Fri Dec 30, 2011 6:30 pm Post subject:

daj95376 wrote:

Code:

Is this an S-wing?

ronk

Joined: 07 May 2006
Posts: 398

Posted: Fri Dec 30, 2011 6:35 pm Post subject:

daj95376 wrote:

JC Van Hay wrote:

the following Wing is simpler but harder to find or to justify IMHO ... 8r7c3=(8-7)r7c5=7r9c5-(7=5)r9c3 : -5r7c3; stte

I consider it a beautiful and somewhat common pattern.

Wouldn't go so far as to say "beautiful", but I certainly like it. When players start looking for an elimination in one of the "pincer" cells, its commonality will become recognized.

BTW an s-wing has the bivalue as its middle SI.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Fri Dec 30, 2011 6:54 pm Post subject:

arkietech wrote:

Is this an S-wing?

Not even close from what I can tell.

Regards, Danny

ronk

Joined: 07 May 2006
Posts: 398

Posted: Fri Dec 30, 2011 7:19 pm Post subject:

daj95376 wrote:

arkietech wrote:

Is this an S-wing?

Not even close from what I can tell.

999_springs called it a "hybrid wing 2" here, and stated it was previously named. I haven't located that exact pattern in a prior post, but am sure udosuk was the originator of the hybrid-wing term.

Hmm, if I thought sudopedia could get spamming under control and show evidence of owner/moderator support, with backups the most important, I could probably be motivated to update it with info on wings.

keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Fri Dec 30, 2011 10:24 pm Post subject:

ronk wrote:

daj95376 wrote:

arkietech wrote:

Is this an S-wing?

Not even close from what I can tell.

Why not copy Sudopedia into Wikipedia?

Keith

ronk

Joined: 07 May 2006
Posts: 398

Posted: Sat Dec 31, 2011 12:36 am Post subject:

keith wrote:

Why not copy Sudopedia into Wikipedia?

If that were appropriate, which I doubt, it would require 100+ times the effort of what I had in mind.

keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Sat Dec 31, 2011 1:56 am Post subject:

ronk wrote:

keith wrote:

Why not copy Sudopedia into Wikipedia?

If that were appropriate, which I doubt, it would require 100+ times the effort of what I had in mind.

Well then, why not just copy the relevant Sudopedia article here and add your contribution? (I have no guarantee that this site is any more durable than Sudopedia.)

By the way, I was not making a drive-by comment. I am prepared to fund a realistic proposal to take the information in Sudopedia and put it in a less fragile place like Wikipedia.

So, if we put Sudopedia into Wkipedia, Ruud is going to sue us? I think not!

Ron, I think that writing down your knowledge should not depend on the repository. Post it here, post it there, it will be preserved. But, please, do write it down.

Best wishes,

Keith

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sat Dec 31, 2011 4:55 pm Post subject:

This might be the desired solution by the puzzle's creator: 7-cell XY-Chain

Code:

+--------------------------------------------------------------+
| 17 17 2 | 5 4 9 | 3 8 6 |
| 5 3 6 | 7 2 8 | 1 9 4 |
| 9 8 4 | c36 136 b16 | 5 2 7 |
|--------------------+--------------------+--------------------|
| 2 5 9 | 8 e36 4 | 7 136 f13 |
| 8 4 1 | d36 5 7 | 2 36 9 |
| 367 67 37 | 1 9 2 | 4 5 8 |
|--------------------+--------------------+--------------------|
| 1367 167 3578 | 4 1678 156 | 9 13 2 |
| 4 9 358 | 2 18 a15 | 6 7 13-5 |
| 167 2 57 | 9 167 3 | 8 4 g15 |
+--------------------------------------------------------------+
# 42 eliminations remain

(5=1=6=3=6=3=1=5)r8c6,r3c6,r3c4,r5c4,r4c5,r4c9,r9c9 => r8c9<>5

But I'm partial to these URs found by my solver:

Code:

after basics
+---------------------------------------------------------------+
| *17 *17 2 | 5 4 9 | 3 8 6 |
| 5 3 6 | 7 2 8 | 1 9 4 |
| 9 8 4 | 36 136 16 | 5 2 7 |
|---------------------+--------------------+--------------------|
| 2 5 9 | 8 36 4 | 7 136 13 |
| 8 4 1 | 36 5 7 | 2 36 9 |
| 367 67 37 | 1 9 2 | 4 5 8 |
|---------------------+--------------------+--------------------|
| *17+36 *17+6 3578 | 4 1678 156 | 9 13 2 |
| 4 9 358 | 2 18 15 | 6 7 135 |
| %167 2 57 | 9 167 3 | 8 4 15 |
+---------------------------------------------------------------+
# 42 eliminations remain

r17c12 <17> UR via s-link + N_Singles <> 1 r7c1 using r9c1=6
r17c12 <17> UR via s-link <> 7 r7c1

Code:

after basics
+---------------------------------------------------------------+
| 17 17 2 | 5 4 9 | 3 8 6 |
| 5 3 6 | 7 2 8 | 1 9 4 |
| 9 8 4 | 36 136 16 | 5 2 7 |
|---------------------+--------------------+--------------------|
| 2 5 9 | 8 36 4 | 7 136 13 |
| 8 4 1 | 36 5 7 | 2 36 9 |
| 367 67 37 | 1 9 2 | 4 5 8 |
|---------------------+--------------------+--------------------|
| *67+13 %167 3578 | 4 *67+18 156 | 9 13 2 |
| 4 9 358 | 2 18 15 | 6 7 135 |
| *67+1 2 57 | 9 *67+1 3 | 8 4 15 |
+---------------------------------------------------------------+
# 42 eliminations remain

r79c15 <67> UR via s-link + N_Singles <> 6 r7c1 using r7c2=1

Code:

after basics: extraneous ... but interesting
+---------------------------------------------------------------+
| %17 17 2 | 5 4 9 | 3 8 6 |
| 5 3 6 | 7 2 8 | 1 9 4 |
| 9 8 4 | 36 136 16 | 5 2 7 |
|---------------------+--------------------+--------------------|
| 2 5 9 | 8 36 4 | 7 136 13 |
| 8 4 1 | 36 5 7 | 2 36 9 |
| 367 67 37 | 1 9 2 | 4 5 8 |
|---------------------+--------------------+--------------------|
| *16+37 167 3578 | 4 *16+78 156 | 9 %13 2 |
| 4 9 358 | 2 18 15 | 6 7 135 |
| *16+7 2 57 | 9 *16+7 3 | 8 4 15 |
+---------------------------------------------------------------+
# 42 eliminations remain

r79c15 <16> UR via s-link + N_Singles <> 1 r7c5 using r1c1=7 & r7c7=3

ronk

Joined: 07 May 2006
Posts: 398

Posted: Mon Jan 02, 2012 4:19 am Post subject:

keith wrote:

So, if we put Sudopedia into Wkipedia, Ruud is going to sue us? I think not!

I think not as well. Just am not convinced a "page per sudoku technique" structure is appropriate for wikipedia. After all, it is just a hobby, a pastime.

keith wrote:

Well then, why not just copy the relevant Sudopedia article here and add your contribution? (I have no guarantee that this site is any more durable than Sudopedia.)

I don't think there really is a relevant article, except possibly using the xy-wing article as a segue. I'm thinking something like "The Wings of Sudoku" which would detail all the three strong link possibilities. Now this has all been done before, by Myth Jellies, udosuk, 999_Springs and probably others, in various forms and various stages of completeness.

keith wrote:

I think that writing down your knowledge should not depend on the repository. Post it here, post it there, it will be preserved. But, please, do write it down.

While I appreciate the flowers, I think you over-estimate my knowledge. Moreover, writing anything more than a few paragraphs has always been a struggle for me. That's why I tend to post a lot of one-liners. Smile

But I'll give "The Wings of Sudoku" further thought.

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