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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Oct 22, 2011 1:26 am Post subject: Free Press October 20, 2011 (Thursday) |
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| Code: | Puzzle: FP102011
+-------+-------+-------+
| . . . | . . 5 | . . . |
| 2 . 7 | 3 6 . | . . 8 |
| . 9 . | . . 7 | . 4 . |
+-------+-------+-------+
| . 4 . | . 8 . | . 3 . |
| 8 . 9 | . . . | 2 . 4 |
| . 5 . | . 4 . | . . . |
+-------+-------+-------+
| . 6 . | 5 . . | . 1 . |
| 5 . . | . 9 . | 7 . 3 |
| . . . | 2 . . | . . . |
+-------+-------+-------+ |
Keith |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Oct 22, 2011 3:18 am Post subject: |
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| Code: | *-----------------------------------------------------------*
| 4 38 368 | 9 1 5 | 36 2 7 |
| 2 1 7 | 3 6 4 | 59 59 8 |
|*36 9 5 | 8 2 7 | 136 4 *16 |
|-------------------+-------------------+-------------------|
| 16 4 26 | 7 8 29 | 159 3 159 |
| 8 7 9 | 1 5 3 | 2 6 4 |
|*13 5 23 | 6 4 29 | 8 7 9-1 |
|-------------------+-------------------+-------------------|
| 79 6 34 | 5 37 8 | 49 1 2 |
| 5 2 1 | 4 9 6 | 7 8 3 |
| 79 38 348 | 2 37 1 | 4569 59 569 |
*-----------------------------------------------------------*
xy-wing |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 22, 2011 3:51 am Post subject: |
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Yes,
There's an unhelpful 59 UR in there too.
Keith |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sat Oct 22, 2011 4:33 am Post subject: |
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I wish that I could say that I found this gem manually.
| Code: | +---------------------------------------------------------------+
| 4 *38 *38+6 | 9 1 5 | 3-6 2 7 |
| 2 1 7 | 3 6 4 | *59 *59 8 |
| 36 9 5 | 8 2 7 | 136 4 16 |
|--------------------+--------------------+---------------------|
| 16 4 26 | 7 8 29 | 159 3 159 |
| 8 7 9 | 1 5 3 | 2 6 4 |
| 13 5 23 | 6 4 29 | 8 7 19 |
|--------------------+--------------------+---------------------|
| 79 6 34 | 5 37 8 | 49 1 2 |
| 5 2 1 | 4 9 6 | 7 8 3 |
| 79 *38 *38+4 | 2 37 1 | *59+46 *59 569 |
+---------------------------------------------------------------+
# 36 eliminations remain
UR38[(6)r1c3=(4)r9c3] - UR59[(4=6)r9c7] => r1c7<>6
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Last edited by daj95376 on Sat Oct 22, 2011 4:33 am; edited 1 time in total |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Oct 22, 2011 4:33 am Post subject: |
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| I used the same XY-Wing. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 22, 2011 5:26 am Post subject: |
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| daj95376 wrote: | I wish that I could say that I found this gem manually.
| Code: | +---------------------------------------------------------------+
| 4 *38 *38+6 | 9 1 5 | 3-6 2 7 |
| 2 1 7 | 3 6 4 | *59 *59 8 |
| 36 9 5 | 8 2 7 | 136 4 16 |
|--------------------+--------------------+---------------------|
| 16 4 26 | 7 8 29 | 159 3 159 |
| 8 7 9 | 1 5 3 | 2 6 4 |
| 13 5 23 | 6 4 29 | 8 7 19 |
|--------------------+--------------------+---------------------|
| 79 6 34 | 5 37 8 | 49 1 2 |
| 5 2 1 | 4 9 6 | 7 8 3 |
| 79 *38 *38+4 | 2 37 1 | *59+46 *59 569 |
+---------------------------------------------------------------+
# 36 eliminations remain
UR38[(6)r1c3=(4)r9c3] - UR59[(4=6)r9c7] => r1c7<>6
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Danny,
Nice find!
I was on a different path of looking for the DP on the bottom floor, 79 - 34 - 37 - 49 when I noticed the XY-wing.
Keith |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sat Oct 22, 2011 12:50 pm Post subject: |
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Keith, I was also looking for DPs manually when I noticed the UR Type 1 and the UR Type 4 ... but not their connection. Finally, I gave up and ran the puzzle through my solver. You don't want to know the words I called myself when it popped out the connection between the two URs. _  _
The connection between the URs doesn't become apparent (to me) until the grid is organized with the extra candidates separate from the UR candidates. Besides, the UR Type 4 was misleading because I wanted to eliminate the 3s.
Regards, Danny |
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Clement
Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
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| Posted: Sat Oct 22, 2011 4:11 pm Post subject: Free Press October 20, 2011(Thursday) |
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| The W-Wing 16 with strong link 1 in col 7; r3c1<>6 solves it as well. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Oct 27, 2011 10:16 pm Post subject: |
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Marty,
Take a look at the original puzzle.
There is a naked single:
R2C2 must be <1>.
There are also hidden singles:
R2C6 is the only square in row 2 that can be <4>.
R8C2 is the only square in column 2 that can be <2>.
R3C3 is the only square in column 3 that can be <5>.
R5C5 is the only square in column 5 that can be <5>.
Sudoku Susser calls Naked Singles "Forced", and calls Hidden Singles "Pinned".
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Oct 28, 2011 1:39 am Post subject: |
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I did the puzzle on Draw/Play and clicked Auto sweep after doing the standard cross-hatching and got this.
| Code: |
+------------------+----------------+------------------+
| 1346 138 13468 | 1489 12 5 | 1369 2679 12679 |
| 2 1 7 | 3 6 149 | 159 59 8 |
| 136 9 5 | 18 12 7 | 136 4 126 |
+------------------+----------------+------------------+
| 167 4 126 | 1679 8 1269 | 1569 3 15679 |
| 8 137 9 | 167 5 136 | 2 67 4 |
| 1367 5 1236 | 1679 4 12369 | 1689 6789 1679 |
+------------------+----------------+------------------+
| 3479 6 2348 | 5 37 348 | 489 1 29 |
| 5 128 1248 | 1468 9 1468 | 7 268 3 |
| 13479 1378 1348 | 2 137 13468 | 45689 5689 569 |
+------------------+----------------+------------------+
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Play this puzzle online at the Daily Sudoku site
I suppose this illustrates the Naked Single. (It's better illustrated on the Draw/Play grid where it shows as a pencil mark, not a solved cell). In doing this with pencil and paper I'd just write 1 in r2c2 and move on. The concept of Naked Single would never occur to me and I don't see how I would use it. |
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