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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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 Posted: Sun Jun 12, 2016 1:15 pm Post subject: June 12 Hard |
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| Code: |
+--------------+----------+---------------+
| 4 7 15 | 6 35 9 | 138 2 18 |
| 6 2359 259 | 8 1 45 | 34 7 49 |
| 139 39 8 | 7 34 2 | 6 5 149 |
+--------------+----------+---------------+
| 7 49 149 | 3 8 45 | 2 6 1459 |
| 129 249 3 | 19 45 6 | 7 489 14589 |
| 5 8 6 | 19 2 7 | 14 49 3 |
+--------------+----------+---------------+
| 23 1 24 | 5 7 8 | 9 34 6 |
| 39 3459 459 | 2 6 1 | 348 348 7 |
| 8 6 7 | 4 9 3 | 5 1 2 |
+--------------+----------+---------------+
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Play this puzzle online at the Daily Sudoku site
having solved it Via a simple XY wing 345 pivoted at r2c6, I went back to the beginning since it must be soluble by "simple fundamentals"
So at the "critical point" I found another hard solution that I don't recognise as a formal one. Whether r3c1 or r3c8 is 1 r3c5 becomes 4 very quickly and that solves it.
The draw play solutions move (cannot explain) is to set r3c1 to 1 which solves it _ I cannot see the logic for this move!
HELP
Last edited by George Woods on Sun Jun 12, 2016 6:35 pm; 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: Sun Jun 12, 2016 1:37 pm Post subject: |
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| Quote: | | I Have forgotten how to copy a puzzle int0 this text ANYWAY |
George,
In Draw/Play you click the Ascii button to the right of the grid. A small window will appear. Click in the window and then copy with Ctrl/C, then Paste into the message box. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Sun Jun 12, 2016 6:36 pm Post subject: |
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| thanks Marty I have put the critical point into my question |
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dongrave
Joined: 06 Mar 2014
Posts: 568
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| Posted: Sun Jun 12, 2016 7:50 pm Post subject: |
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| Boy, that was driving me nuts George! I finally noticed that the 9's in c9 of box 3 are locked so they can be removed from r45c9 and the 4's in r6 of box 6 are locked so they can also be removed from r45c9 - and that leaves the hidden 49 pair in r23c9 (which removes the 1 from r3c9) which leaves the lone 1 in r3 at r3c1! Good one! |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Jun 12, 2016 8:39 pm Post subject: |
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| You can start off with the 4s in r6 locked in b6 and after the eliminations in r45c9 then the c9 4s are locked in b3 => -4r2c7=3r2c7=> 18 pair in r1c79. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Sun Jun 12, 2016 9:20 pm Post subject: a type of XY wing |
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Thanks for the non wing solutions
In reply to my own implied question that sets r3c5 to 4
We have a kind of XY wing 153 pivot r1c3 the only departure from norm is that if the pivot is 1 it creates a 3 in box1 row 3 either c1 or c2 - i.e. two wings of 3 bear down on r3c5 which therefore cannot be 3
Is this move called an XY or an extended XY or what? |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Jun 12, 2016 10:43 pm Post subject: |
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| Quote: | We have a kind of XY wing 153 pivot r1c3 the only departure from norm is that if the pivot is 1 it creates a 3 in box1 row 3 either c1 or c2 - i.e. two wings of 3 bear down on r3c5 which therefore cannot be 3
Is this move called an XY or an extended XY or what? |
| Code: | +--------------+----------+---------------+
| 4 7 15 | 6 35 9 | 138 2 18 |
| 6 2359 259 | 8 1 45 | 34 7 49 |
| 139 39 8 | 7 34 2 | 6 5 149 |
+--------------+----------+---------------+
| 7 49 149 | 3 8 45 | 2 6 1459 |
| 129 249 3 | 19 45 6 | 7 489 14589 |
| 5 8 6 | 19 2 7 | 14 49 3 |
+--------------+----------+---------------+
| 23 1 24 | 5 7 8 | 9 34 6 |
| 39 3459 459 | 2 6 1 | 348 348 7 |
| 8 6 7 | 4 9 3 | 5 1 2 |
+--------------+----------+---------------+ |
It's certainly not an extended XY. Some people use that term when there are three identical bivalue cells in a chain which serve as a pivot cell. Such as 13-15-15-15-35. I do not see two wings which bear down on r3c5.
Maybe this is an XY-Wing with a pseudo cell, as r3c12 act as a single 13 cell. Or maybe a grouped wing.
The right person to answer your question is Keith and I'm sure he will if he sees this. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Wed Jun 15, 2016 12:19 am Post subject: |
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| Marty R. wrote: | | The right person to answer your question is Keith and I'm sure he will if he sees this. |
I'm not so sure. I am also not in favor of complicated solutions when simpler will suffice.
At the start:
| Code: | +-------------------+-------------------+-------------------+
| 4 357 157 | 6 357 9 | 138 2 18 |
| 6 23579 2579 | 378 1 4578 | 348 34789 489 |
| 139 379 8 | 37 347 2 | 1346 5 1469 |
+-------------------+-------------------+-------------------+
| 7 2459 12459 | 139 8 145 | 1245 6 1459 |
| 1259 2459 3 | 19 459 1456 | 7 1489 14589 |
| 159 8 14569 | 179 2 14567 | 145 149 3 |
+-------------------+-------------------+-------------------+
| 238 1 247 | 5 7 78 | 9 348 468 |
| 23589 23459 2459 | 1289 6 18 | 13458 1348 7 |
| 589 6 579 | 4 79 3 | 158 18 2 |
+-------------------+-------------------+-------------------+
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After 11 singles:
| Code: | +-------------------+-------------------+-------------------+
| 4 7 15 | 6 35 9 | 138 2 18 |
| 6 2359 259 | 8 1 45 | 34 7 49 |
| 139 39 8 | 7 34 2 | 6 5 149 |
+-------------------+-------------------+-------------------+
| 7 459 1459 | 3 8 45 | 2 6 1459 |
| 1259 2459 3 | 19 45 6 | 7 1489 14589 |
| 159 8 6 | 19 2 7 | 145 149 3 |
+-------------------+-------------------+-------------------+
| 23 1 24 | 5 7 8 | 9 34 6 |
| 3589 3459 459 | 2 6 1 | 3458 348 7 |
| 58 6 7 | 4 9 3 | 158 18 2 |
+-------------------+-------------------+-------------------+ |
we get to intersections. After only a couple of those, we get here:
| Code: | +----------------+----------------+----------------+
| 4 7 15 | 6 35 9 | 138 2 18 |
| 6 2359 259 | 8 1 45 | 34 7 49 |
| 139 39 8 | 7 34 2 | 6 5 149 |
+----------------+----------------+----------------+
| 7 459 1459 | 3 8 45 | 2 6 15 |
| 1259 2459 3 | 19 45 6 | 7 189 158 |
| 159 8 6 | 19 2 7 | 145 149 3 |
+----------------+----------------+----------------+
| 23 1 24 | 5 7 8 | 9 34 6 |
| 3589 3459 459 | 2 6 1 | 3458 348 7 |
| 58 6 7 | 4 9 3 | 158 18 2 |
+----------------+----------------+----------------+
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The triple 158 or hidden pair 49 in C9 solves it.
Keith |
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