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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Thu Jun 30, 2011 4:08 pm Post subject: Puzzle 11/06/30: ~ XY |
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| Code: | +-----------------------+
| . . . | . . . | 2 7 6 |
| . 7 1 | . . . | . 5 . |
| . 2 4 | . . 7 | 1 . . |
|-------+-------+-------|
| . . . | 4 . 3 | . 2 . |
| . . . | . 8 . | 4 . . |
| . . 3 | 2 . 6 | 5 . . |
|-------+-------+-------|
| 4 . 7 | . 2 9 | 6 . 5 |
| 2 9 . | 6 . . | . . 7 |
| 3 . . | . . . | 9 4 . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Fri Jul 01, 2011 3:01 pm Post subject: |
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I worked hard on this puzzle and found a couple of weird, messy steps that did not do any significant damage before I found a reasonably clean back breaker...........
almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;
xy-wing (35-8) vertex r3c4; r2c4,r9c6<>8
I would appreciate any suggestion how to combine the two statements for the almost xy-chain.
Ted |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Jul 01, 2011 3:18 pm Post subject: |
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Ted,
Performing a Kraken Cell on r2c4 is a common alternative for your scenario. All you need to do is split your chain at r2c4:
| Code: | Kraken Cell r2c4:
read l-to-r: ( =9)r2c4-r5c4=r6c5-(9=8)r6c8 -(8)r78c8
read r-to-l: (8)r78c8- (8)r8c7=(8)r2c7-(8= )r2c4
read l-to-r: ( 3)r2c4-r7c4=r8c5-(3=8)r8c7 -(8)r78c8
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You can also perform a 2-String Kite for r2c4<>3, and then use your chain -- which doesn't appear to be an XY-Chain pattern.
Regards, Danny |
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Luke451
Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California
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| Posted: Fri Jul 01, 2011 9:18 pm Post subject: |
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| tlanglet wrote: | I worked hard on this puzzle and found a couple of weird, messy steps that did not do any significant damage before I found a reasonably clean back breaker...........
almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;
xy-wing (35-8) vertex r3c4; r2c4,r9c6<>8
I would appreciate any suggestion how to combine the two statements for the almost xy-chain.
Ted |
*Maybe* this'll do it, avoid a net and keep your xy.
(8=3)r8c7-r8c5=r7c4-(3)r2c4=[xy chain that I'm too lazy to notate but lives in the * cells]
| Code: | *-----------------------------------------------------------*
| 589 3 89 | 1589 149 458 | 2 7 6 |
| 689 7 1 |*389 369 2 |*38 5 4 |
| 568 2 4 | 358 36 7 | 1 389 89 |
|-------------------+-------------------+-------------------|
| 189 68 689 | 4 5 3 | 7 2 189 |
| 79 5 2 |*79 8 1 | 4 6 3 |
| 1789 4 3 | 2 *79 6 | 5 *89 189 |
|-------------------+-------------------+-------------------|
| 4 18 7 | 138 2 9 | 6 138 5 |
| 2 9 58 | 6 134 458 |*38 138 7 |
| 3 168 568 | 1578 17 58 | 9 4 2 |
*-----------------------------------------------------------* |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Fri Jul 01, 2011 9:49 pm Post subject: |
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| tlanglet wrote: | almost xy-chain with r2c4(89=3); r78c8<>8
If r2c4=89: (8)r8c7=(8)r2c7-(8=9)r2c4-r5c4=r6c5-(9=8)r6c8;
If r2c4=(3): (3)r2c4-r7c4=r8c5-(3=8)r8c7;
...
I would appreciate any suggestion how to combine the two statements for the almost xy-chain. |
I see no clever way to convert the net to a chain. I suppose this does you no good but, in modernized nice-loop notation, it would look like this:
r78c8 -8- r8c7 =8= r2c7 -8- r2c4 {-3- r7c4 =3= r8c5 -3- r8c7 -8- r78c8} -9- r5c4 =9= r6c5 -9- r6c8 -8- r78c8 ==> r78c8<>8 |
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dejsmith
Joined: 23 Oct 2005
Posts: 42
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| Posted: Fri Jul 01, 2011 10:23 pm Post subject: |
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How come you cannot use the Kite in r7/c7 to eliminate the 3 in r2c4? Then why isn't that an XY Chain, starting at r8c7: 83-38-89-97-79-98; & r78c8<>8?
I tried something different using a UR & 2 kites, but did not see the XY Chain. Instead I tried looking for an almost pattern & chose an ANP in r4c3; 89-6. 6 led to a contradiction & 89 solved the puzzle. Was I just lucky & do I have an incorrect understanding of these techniques?
Dave |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Jul 02, 2011 4:52 am Post subject: |
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Finned X-Wing; r2c4<>3
W-Wing (89), SL 9, c5, flightless with transport; r2c7, r3c4<>8
XY-Wing (385); r1c6, r9c4<>5 |
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