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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Mon Jun 07, 2010 4:48 pm Post subject: Puzzle 10/06/07: (C) Advanced |
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First puzzle from new file.
| Code: | +-----------------------+
| . . . | . . . | . 2 1 |
| . 8 2 | . 7 . | 6 3 4 |
| . 9 3 | . 4 . | . . . |
|-------+-------+-------|
| . . . | 7 . . | . . . |
| . 4 8 | . . . | 2 . 3 |
| . . . | . . 4 | 1 . 9 |
|-------+-------+-------|
| . 2 . | . 3 9 | 4 1 . |
| 9 7 . | . . . | 3 . . |
| 3 6 . | . 1 7 | . . 2 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
| Code: | after basics
+--------------------------------------------------------------+
| 4 5 7 | 3 68 68 | 9 2 1 |
| 1 8 2 | 9 7 5 | 6 3 4 |
| 6 9 3 | 12 4 12 | 7 58 58 |
|--------------------+--------------------+--------------------|
| 25 1 9 | 7 2568 3 | 58 4 568 |
| 57 4 8 | 15 9 16 | 2 567 3 |
| 257 3 6 | 258 258 4 | 1 578 9 |
|--------------------+--------------------+--------------------|
| 8 2 5 | 6 3 9 | 4 1 7 |
| 9 7 1 | 4 258 28 | 3 568 568 |
| 3 6 4 | 58 1 7 | 58 9 2 |
+--------------------------------------------------------------+
# 35 eliminations remain
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Jun 07, 2010 9:40 pm Post subject: |
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One of many possible xy starts.. two steps
| Quote: | xy-chain (1=2)r3c6-(2=8)r8c6-(8=5)r9c4-(5=1)r5c4; r3c4<>1, r5c6<>1
remote pair(58); r4c5<>58 |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jun 08, 2010 3:55 am Post subject: |
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I think I used one of the other xy starts mentioned by Peter......
| Quote: | Not sure if it has a name: (8=5)r9c4 - (5=1)r5c4 - (1=6)r5c6 - (6=8)r1c6; r8c6<>8
Remote Pair 58; r4c5<>58 |
Ted |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jun 08, 2010 4:44 am Post subject: |
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A fun step:
Almost Almost UR (AAUR) 57 in r56c18 with x-wing 7 overlay; r6c8<>5 (I believe that this is called a Hidden UR)
But it may also be viewed as AUR57 r56c18 = (6)r5c8
To prevent the AUR, r6c1=2 or r6c8=8
(2)r6c1 - (2=5)r4c1; r4c5<>5
(8)r6c8 - (8=5)r4c7; r4c5<>5, and finally
(6)r5c8 - (6=1)r5c6 - (1=5)r5c4; r4c5<>5
Thus both the AUR57 and the extra "almost" condition force r4c5<>5 for an additional deletion.
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Tue Jun 08, 2010 4:46 am Post subject: |
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How about an XY-Chain that performs eliminations on two different candidate values.
| Code: | (2=1)r3c4 - (1=5)r5c4 - (5=8)r9c4 - (8=2)r8c6 - (2=1)r3c6 => r3c4<>1, r3c6<>2
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Or, you could think of it as two distinct XY-Chains, but what's the fun in that.
| Code: | (2=1)r3c4 - (1=5)r5c4 - (5=8)r9c4 - (8=2)r8c6 => r3c6<>2
(1=5)r5c4 - (5=8)r9c4 - (8=2)r8c6 - (2=1)r3c6 => r3c4<>1
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Jun 08, 2010 7:09 am Post subject: |
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Yes Danny - saw that xy that sorts out its own chain ends yesterday, but couldn't post from my handheld.
Also saw the far less entertaining scenario of consecutive xy elimination but this time on 8s:
(8=6)r1c6-(6=1)r5c6-(1=5)-(5=8)r9c4 so r8c6<>8
Then a 58 skyscraper or classic RP configuration removing 58 at r4c5 as in Peter's solution. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jun 08, 2010 11:42 am Post subject: |
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MM: Your chain on (8) is the same as the one I posted, just in reverse order.
Also, this chain does have a pattern name: ALS_XZ (158)r59c4 & (168)r15c6 with X=1 & Z=8)
Ted |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Tue Jun 08, 2010 11:53 am Post subject: |
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| tlanglet wrote: | MM: Your chain on ( is the same as the one I posted, just in reverse order.
Also, this chain does have a pattern name: ALS_XZ (158)r59c4 & (168)r15c6 with X=1 & Z= |
[edit: The ALS-xz is a short ALS-chain. The ALS-chain] technique subsumes the xy-chain technique ... but an xy-chain is still most appropriately called an xy-chain.
Last edited by ronk on Tue Jun 08, 2010 1:54 pm; edited 1 time in total |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Tue Jun 08, 2010 11:58 am Post subject: |
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| ronk wrote: | | tlanglet wrote: | MM: Your chain on ( is the same as the one I posted, just in reverse order.
Also, this chain does have a pattern name: ALS_XZ (158)r59c4 & (168)r15c6 with X=1 & Z= |
The ALS-xz technique subsumes the xy-chain technique ... but an xy-chain is still most appropriately called an xy-chain. |
I agree!
Ted |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Jun 08, 2010 1:42 pm Post subject: |
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| Thanks for pointing out the ALS XZ Ted - I like them aesthetically as you know. Amen Ronk. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Jun 09, 2010 4:21 am Post subject: |
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Skyscraper (8)
Type 6 UR (57)
Kite (5) |
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