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ravel
Joined: 21 Apr 2006
Posts: 536
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 Posted: Sat Dec 15, 2007 1:28 pm Post subject: UR - eh DP |
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By gsf
| Code: | . . . | 3 9 8 | . . .
. 5 . | . 2 . | . 6 .
. . . | . . . | . . .
------+-------+------
8 . . | . . . | . . 9
6 2 . | . 5 . | . 4 1
7 . . | . . . | . . 8
------+-------+------
. . . | . . . | . . .
. 4 . | . 6 . | . 2 .
. . . | 4 1 9 | . . . |
After a long way and 2 x-wings an 8 cell UR (type 1) - [edit:] better UL for "unique loop" - jumped into my eyes, which easily solved it. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sat Dec 15, 2007 2:04 pm Post subject: |
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X-wings and one other coloring elimination (kite?):
x-wing(8) c28,
x-wing(9) c28;
x-wing(8) r28;
(multi-)coloring (7) :-r9c7=r1c7-r2c9=r2c3-; r9c3<>7
got me to this position:
| Code: |
+--------------------------+--------------------------+--------------------------+
| 4 67 267 | 3 9 8 | 57 1 257 |
| 39 5 378 | 1 2 4 | 89 6 37 |
| 123 89 123 | 56 7 56 | 4 89 23 |
+--------------------------+--------------------------+--------------------------+
| 8 3 5 | 26 4 1 | 26 7 9 |
| 6 2 9 | 8 5 7 | 3 4 1 |
| 7 1 4 | 9 3 26 | 26 5 8 |
+--------------------------+--------------------------+--------------------------+
| 35 679 67 | 257 8 25 | 1 39 4 |
| 19 4 18 | 57 6 3 | 89 2 57 |
| 235 78 23 | 4 1 9 | 57 38 6 |
+--------------------------+--------------------------+--------------------------+
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An xy-chain/w-wing '39' (r2c1 ... r7c8 via r2c7,r3c8) removes 3 from r7c1.
That solves it. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Sat Dec 15, 2007 2:09 pm Post subject: |
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I already stopped here (didnt spot the w-wing yet)
| Code: | *--------------------------------------------------*
| 4 67 267 | 3 9 8 | 57 1 257 |
| 39 5 378 | 1 2 4 | 89 6 37 |
| 123 89 123 | 56 7 56 | 4 389 23 |
|----------------+----------------+----------------|
| 8 3 5 | 26 4 1 | 26 7 9 |
| 6 2 9 | 8 5 7 | 3 4 1 |
| 7 1 4 | 9 3 26 | 26 5 8 |
|----------------+----------------+----------------|
| 35 679 367 | 257 8 25 | 1 39 4 |
| 19 4 18 | 57 6 3 | 89 2 57 |
| 235 78 237 | 4 1 9 | 57 38 6 |
*--------------------------------------------------*
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sat Dec 15, 2007 4:34 pm Post subject: |
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Next (optional?) step for me, before the xy-chain, was to remove 7 from r9c3 (marked #)
| Code: |
*--------------------------------------------------*
| 4 67 267 | 3 9 8 | 57# 1 257 |
| 39* 5 37#8 | 1 2 4 | 89* 6 37# |
| 123 89 123 | 56 7 56 | 4 389* 23 |
|----------------+----------------+----------------|
| 8 3 5 | 26 4 1 | 26 7 9 |
| 6 2 9 | 8 5 7 | 3 4 1 |
| 7 1 4 | 9 3 26 | 26 5 8 |
|----------------+----------------+----------------|
|-3 5 679 367 | 257 8 25 | 1 39* 4 |
| 19 4 18 | 57 6 3 | 89 2 57 |
| 235 78 23-7 | 4 1 9 | 57# 38 6 |
*--------------------------------------------------*
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That gives a naked triple 2,3,5 in box 7, which removes 3 from r7c3.
3 in r3c8 can be removed, too, by box/line interaction)
It is only then that the xy-chain (marked *)appears. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Sat Dec 15, 2007 7:21 pm Post subject: |
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Hm, the w-wing with strong link for 9 in c7 was there for some time, but i missed it.
| Code: | *--------------------------------------------------*
| 4 67 267 | 3 9 8 | 57 1 257 |
| 39 5 378 | 1 2 4 | 89 6 37 |
| 123 89 123 |#56 7 #56 | 4 389 23 |
|----------------+----------------+----------------|
| 8 3 5 |#26 4 1 |#26 7 9 |
| 6 2 9 | 8 5 7 | 3 4 1 |
| 7 1 4 | 9 3 #26 |#26 5 8 |
|----------------+----------------+----------------|
| 35 679 367 |#257 8 #25 | 1 39 4 |
| 19 4 18 | 57 6 3 | 89 2 57 |
| 235 78 237 | 4 1 9 | 57 38 6 |
*--------------------------------------------------* |
Instead i saw the marked DP. See here. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sat Dec 15, 2007 7:44 pm Post subject: |
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x-wings on 8 and 9
that is after a multitude of naked pairs, triples, box line |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sat Dec 15, 2007 7:49 pm Post subject: |
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That is a great example of more complicated DPs, ravel!
I always suspected that the pattern would bend and change candidates but never had a chance (well, maybe a chance but not the need) to follow up on this. As a matter of fact, I recognize that pattern in a grid because it is very similar to the pattern you get in coloring sometimes: starts as a pair in one row, but makes no xwing and "turns" instead. Now that I know these patterns are also DPs they will be of great help.
So, just to test my newfound knowledge, the marked DP in your grid makes r7c4=7, right? Simple Type 1. |
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