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Puzzle 10/09/13: C

dailysudoku.com Forum Index -> Puzzles by daj

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daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Mon Sep 13, 2010 5:09 am Post subject: Puzzle 10/09/13: C

Code:

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

Play this puzzle online at the Daily Sudoku site

peterj

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

Posted: Mon Sep 13, 2010 8:17 am Post subject:

Stumbled on this one-step DP move

Quote:

ADP(45) r17c56 [(6)r1c6=(1)r7c5]
but (6)r1c6=(6-3)r3c6=r8c6 - (3=1)r9c5 - (1)r7c5 contradiction ; r1c6=6

Last edited by peterj on Mon Sep 13, 2010 8:56 am; edited 1 time in total

JC Van Hay

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

Posted: Mon Sep 13, 2010 8:31 am Post subject:

Me too ! ... Very Happy

Quote:

To avoid DP (45)R17C56 : SIS[(6)r1c6,(1)r7c5-(1=3)r9c5-(3=45)r78c6] : (6)r1c6=NP(45)r78c6=> r1c6<>45=6

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Sep 14, 2010 1:05 am Post subject:

Thanks Peter and JC for prompting me to review the UR closer.

When viewed as a <45> UR Type 6 with an X-Wing for <4>, the puzzle doesn't crack.

Code:

+--------------------------------------------------------------+
| 3 2568 568 | 1 *45 *45+6 | 7 268 9 |
| 128 268 4 | 28 9 7 | 5 2368 1236 |
| 1258 9 7 | 28 35 356 | 68 4 126 |
|--------------------+--------------------+--------------------|
| 7 258 58 | 3 6 9 | 1 258 4 |
| 268 4 39 | 5 7 1 | 368 2689 26 |
| 56 1 39 | 4 8 2 | 36 569 7 |
|--------------------+--------------------+--------------------|
| 9 3 56 | 7 *45+1 *45 | 2 16 8 |
| 58 568 1 | 9 2 35 | 4 7 36 |
| 4 7 2 | 6 13 8 | 9 13 5 |
+--------------------------------------------------------------+
# 62 eliminations remain

r17c56 <45> UR Type 6.2233 r1c5,r7c6<>5

However, the threat of a single-digit DP hasn't been eliminated. Leaving:

Code:

+--------------------------------------------------------------+
| 3 2568 568 | 1 *4 *5+6 | 7 268 9 |
| 128 268 4 | 28 9 7 | 5 2368 1236 |
| 1258 9 7 | 28 35 356 | 68 4 126 |
|--------------------+--------------------+--------------------|
| 7 258 58 | 3 6 9 | 1 258 4 |
| 268 4 39 | 5 7 1 | 368 2689 26 |
| 56 1 39 | 4 8 2 | 36 569 7 |
|--------------------+--------------------+--------------------|
| 9 3 56 | 7 *5+1 *4 | 2 16 8 |
| 58 568 1 | 9 2 35 | 4 7 36 |
| 4 7 2 | 6 13 8 | 9 13 5 |
+--------------------------------------------------------------+
# 58 eliminations remain

(5): r1c6 - r3c5 = r7c5 ; <45> sd-DP => r1c6<>5

BTW: strong link eliminations in the original UR would have cracked the puzzle as well.

Code:

r17c56 <45> UR via s-link *** r1c6<>4 (4): r1c6-r1c5=r7c5
r17c56 <45> UR via s-link r7c5<>4
r17c56 <45> UR via s-link r1c5<>5
r17c56 <45> UR via s-link *** r1c6<>5 (5): r1c6-r13c5=r7c5
r17c56 <45> UR via s-link r7c6<>5

Regards, Danny

Marty R.

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

Posted: Tue Sep 14, 2010 10:45 pm Post subject:

I used the Type 6 and a W-Wing on 56.

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