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ravel
Joined: 21 Apr 2006
Posts: 536
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 Posted: Wed Jan 30, 2008 2:31 pm Post subject: Nice and unique |
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| Code: | +-------+-------+-------+
| . . 1 | . . . | 2 . . |
| . 3 4 | . . . | 5 1 . |
| 6 5 . | . . . | . 3 7 |
+-------+-------+-------+
| . . . | 8 . 3 | . . . |
| . . . | 9 4 5 | . . . |
| . . . | 2 . 1 | . . . |
+-------+-------+-------+
| 1 4 . | . . . | . 7 5 |
| . 6 5 | . . . | 3 4 . |
| . . 9 | . . . | 8 . . |
+-------+-------+-------+ TTHsieh |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jan 30, 2008 6:12 pm Post subject: |
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| Very interesting puzzle. I suspect there were more uniqueness eliminations available than I was able to come up with. But I did use a Type 4 UR, an XY-Wing and a Type 1 UR. Then I turned to my Medusa crutch and a couple of wraps finished it off. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Jan 31, 2008 12:00 am Post subject: |
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Two UR's and an XY-wing get me to here:
| Code: | +-------------------+-------------------+-------------------+
| 789 78 1 | 35 35 4679 | 2 689 4689 |
| 789 3 4 | 67 29 2679 | 5 1 689 |
| 6 5 2 | 14 189 489 | 49 3 7 |
+-------------------+-------------------+-------------------+
| 45 129 67# | 8 67# 3 | 149 259 249 |
| 28 128 67# | 9 4 5 | 167# 268 3 |
| 45 89 3 | 2 67# 1 | 4679# 5689 4689 |
+-------------------+-------------------+-------------------+
| 1 4 8 | 36 239 269 | 69 7 5 |
| 27 6 5 | 17 189 789 | 3 4 129 |
| 3 27 9 | 14567 15 467 | 8 26 126 |
+-------------------+-------------------+-------------------+ |
Guess what? A Unique Swordfish! Marked #.
The only way to avoid the DP in C7 is that R7C7 is <6>. Puzzle solved!
(In C7, there is no other place for a <7> than in the cells marked #. To avoid the DP, the cells marked # cannot be <6>. The only other place for a <6> is R7C7.)
Keith |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Thu Jan 31, 2008 7:30 am Post subject: |
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Basics and an xy-wing (27-78-82 pivot r1c2) get one here.
This being a ravel exercise in uniqueness, at this point I did not use one of the xy-chains available
I: pincers '67' in r2c4 and '69' in r7c7 linked via r8c4, r3c4, r3c7; => r7c4=3, and the variant
II:pincers '17' in r8c4 and '27' in r9c2 linked via r3c4,r3c7,r7c7,r9c8; removes 7 from r8c1,r9c4,r9c6
But instead I hope to continue my UR education.
| Code: |
+--------------------------+--------------------------+--------------------------+
| 789 78 1 | 35 35 46789 | 2 689 4689 |
| 2789 3 4 | 67 289 26789 | 5 1 689 |
| 6 5 28 | 14 1289 2489 | 49 3 7 |
+--------------------------+--------------------------+--------------------------+
| 45 129 267 | 8 67 3 | 14679 2569 2469 |
| 238 128 23678 | 9 4 5 | 167 268 2368 |
| 45 89 3678 | 2 67 1 | 4679 5689 34689 |
+--------------------------+--------------------------+--------------------------+
| 1 4 38 | 36 2389 2689 | 69 7 5 |
| 278 6 5 | 17 189 789 | 3 4 129 |
| 237 27 9 | 134567 135 467 | 8 26 126 |
+--------------------------+--------------------------+--------------------------+
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The URs I see (could someone pls confirm or correct the reasoning and typecasting):
A Type 4 - {3,5} r19c45. Since r9c45 are strongly linked in 5, 3 cannot be in either of those 2 cells, therefore r9c1=3, right?
A Type 3 - {6,7} in r46c35. One of r46c3 must be {2,3,8}, together with {2,8} and {3,8} in r37c3 we have a virtual naked triple and r5c3 becomes {6,7} (remove 2,3,8 from r5c3). Right?
Those 2 steps take me to keith's position with the USf (unique swordfish), eventually. I'd just like to make sure I got the reasoning right. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Thu Jan 31, 2008 10:30 am Post subject: |
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Wow, i did not notice the type 3, because the 3 in r9c1 leads to a type 1 there.
Another point of view, which (in this case) leads to the same elimination is, that in the 2 boxes (4 and 5) 6 or 7 must be outside the UR to destroy the deadly pattern. Only in r5c3 there is a 6 and a 7, thus it must be 6 or 7 and 238 can be eliminated.
The same argument here is valid for the two columns 4 and 6. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Thu Jan 31, 2008 5:55 pm Post subject: |
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| nataraj wrote: | | pls confirm or correct the reasoning and typecasting |
| ravel wrote: | | Wow, i did not notice the type 3, because ... |
I take that as a confirmation  . And "wow" ... real flattering  ! Thanks, ravel !
I do have another question, though:
I think I understand your argument "Another point ... eliminated" - makes perfect sense to me. But ...
| ravel wrote: | | The same argument here is valid for the two columns 4 and 6. |
my questions:
- what is the DP there? I guess 67 in r29c46
- But what is the reasoning and the elimination to be made from there?
Thx for your patience! |
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