dailysudoku.com :: View topic - Puzzle 10/09/18: B

dailysudoku.com
Discussion of Daily Sudoku puzzles

FAQ

Memberlist

Usergroups

Profile

Puzzle 10/09/18: B

dailysudoku.com Forum Index -> Puzzles by daj

View previous topic :: View next topic

Author

Message

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sat Sep 18, 2010 4:58 am Post subject: Puzzle 10/09/18: B

Code:

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

Play this puzzle online at the Daily Sudoku site

peterj

Joined: 26 Mar 2010
Posts: 974
Location: London, UK

Posted: Sat Sep 18, 2010 9:40 am Post subject:

One interpretation of the 2/3 SL..

Quote:

s-wing(23) (3)r1c4=r1c9 - (3=2)r8c9 - (2)r2c9=r2c4 ; r1c4<>2

JC Van Hay

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

Posted: Sat Sep 18, 2010 10:13 am Post subject:

A longer single lazy step ...

Quote:

5-SIS AIC : 8C6 3C6 3B9 2C9 9R2 : (8)r1c6=(9)r2c4 : => r1c6<>9

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun Sep 19, 2010 12:33 am Post subject:

While reviewing this puzzle, I noted the similarity between Peter's S-Wing and my solver's M-Wing.

Code:

M-Wing 2B (2=3)r8c9 - r1c9 = (3-2)r1c4 = (2)r2c4 => r2c9<>2

Then, I started examining the <18> UR eliminations and had a feeling that the UR was part of a larger DP in [band 1].
Accept this with a grain of salt!!!

Code:

<1478> DP r13c1359
(3)r13c9 - (3)r3c8
(6)r3c5 - (6=3)r3c4 - (3)r3c8
+-----------------------------------------------------+
| *148 29 *147 | 239 *18 89 | 5 6 *47+3 |
| 6 3 5 | 29 7 4 | 1 8 29 |
| *148 29 *147 | 36 *18+6 5 | 29 7-3 *47+3 |
|-----------------+-----------------+-----------------|
| 9 5 2 | 7 38 38 | 4 1 6 |
| 3 4 6 | 1 5 2 | 8 79 79 |
| 7 1 8 | 69 4 69 | 3 2 5 |
|-----------------+-----------------+-----------------|
| 2 8 3 | 4 9 7 | 6 5 1 |
| 5 6 9 | 8 23 1 | 7 4 23 |
| 14 7 14 | 5 236 36 | 29 39 8 |
+-----------------------------------------------------+
# 40 eliminations remain

peterj

Joined: 26 Mar 2010
Posts: 974
Location: London, UK

Posted: Sun Sep 19, 2010 7:47 am Post subject:

daj95376 wrote:

Accept this with a grain of salt!!!

Danny, is salt needed? Fwiw, it looks good to me. Great spot!

My only reference on the "when is a pattern a MUG?" is myths article here. My interpretation would be that this is a "permeable" MUG. The external cells that can influence the DP are (14)r9c13, (8)r4c5, (7)r3c8 and (7)r5c9. If you consider each of these in turn...

(1)r9c1,(4)r9c2 collapses the MUG to a BUG-Lite (48),(14),(18),(47)

(4)r9c1,(1)r9c2 collapses the MUG to a UR(18) and UR(47)

(8)r4c5 leads to a zero-solution with two 1s in b2

(7)r3c8 and (7)r5c9 leads to a zero-solution with two 3s in b3

So if I understand the original post (and assuming it is right!) then this looks like a nice permeable MUG with the DP killers leading to the elimination you describe.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun Sep 19, 2010 10:55 am Post subject:

peterj wrote:

Danny, is salt needed? Fwiw, it looks good to me. Great spot!

Thanks Peter for confirming that a DP exists. Thanks also for the reference link. Unfortunately, I've read that link (and others) about DPs ... only to come away with a headache and no comprehension of the subject matter.

In this puzzle, I saw:

*) X-Wing on <7> in [band 1]
*) X-Wing on <8> in [band 1]
*) "triple-wing" on <1> overlaying <7/8> X-Wings
*) "triple-wing" on <4> overlaying <7/8> X-Wings

So, I stuck my neck out and called it a DP because it was too "hinkey" (sic?) not to be a DP. _ Laughing

_

Regards, Danny

My latest headache was posted here:

Code:

+-------+-------+-------+ +-------+-------+-------+
|*3 .*1 | 4 . 6 |*8*7 9 | |*1 .*3 | 4 . 6 |*7*8 9 |
| . . . | 1 . . | . . . | | . . . | 1 . . | . . . |
| 6 . 8 | . 7 3 | 1 . . | | 6 . 8 | . 7 3 | 1 . . |
+-------+-------+-------+ +-------+-------+-------+
| . 8 . | 3 . 1 | 5 . 7 | | . 8 . | 3 . 1 | 5 . 7 |
|*1 .*3 | 5 . 7 | 9 . 8 | |*3 .*1 | 5 . 7 | 9 . 8 |
| 5 . . | . . . | . 1 . | | 5 . . | . . . | . 1 . |
+-------+-------+-------+ +-------+-------+-------+
| . . 6 | . . . | . . 5 | | . . 6 | . . . | . . 5 |
|*9 . 5 | 7 3 . | 6*8 . | |*8 . 5 | 7 3 . | 6*9 . |
|*8 . . | 6 . 5 |*7*9 . | |*9 . . | 6 . 5 |*8*7 . |
+-------+-------+-------+ +-------+-------+-------+

The 4-cell DP in [b14] is obvious -- even to me. The 7-cell DP gave me insomnia.

In my mind, performing a cycle on the (89) DP in [band 3] forces an (87) DP in [stack 3].

Code:

+-------+-------+-------+ +-------+-------+-------+
|*3 .*1 | 4 . 6 | 8 7 9 | |*1 .*3 | 4 . 6 |*8*7 9 |
| . . . | 1 . . | . . . | | . . . | 1 . . | . . . |
| 6 . 8 | . 7 3 | 1 . . | | 6 . 8 | . 7 3 | 1 . . |
+-------+-------+-------+ +-------+-------+-------+
| . 8 . | 3 . 1 | 5 . 7 | | . 8 . | 3 . 1 | 5 . 7 |
|*1 .*3 | 5 . 7 | 9 . 8 | |*3 .*1 | 5 . 7 | 9 . 8 |
| 5 . . | . . . | . 1 . | | 5 . . | . . . | . 1 . |
+-------+-------+-------+ +-------+-------+-------+
| . . 6 | . . . | . . 5 | | . . 6 | . . . | . . 5 |
|*9 . 5 | 7 3 . | 6*8 . | |*8 . 5 | 7 3 . | 6*9 . |
|*8 . . | 6 . 5 | 7*9 . | |*9 . . | 6 . 5 |*7*8 . |
+-------+-------+-------+ +-------+-------+-------+

Now, I have 3x 4-cell DPs and no other mapping is needed to address the problem cells.

Marty R.

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

Posted: Sun Sep 19, 2010 12:55 pm Post subject:

An old-fashioned XY-Wing (369), pivot r9c6, flightless with pincer transport; r6c4, r1c6<>9.

Display posts from previous:

	dailysudoku.com Forum Index -> Puzzles by daj	All times are GMT
Page 1 of 1

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