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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Thu Apr 22, 2010 8:00 pm Post subject: Puzzle 10/04/22 ___ Advanced |
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Warmup for Friday's Salsa puzzle.
| Code: | +-----------------------+
| 8 . 2 | . . . | . 1 3 |
| . 9 . | . . 3 | . . 2 |
| 5 . . | 8 . 2 | . 6 7 |
|-------+-------+-------|
| . . 7 | 1 . 5 | . . . |
| . . . | . 2 . | . . . |
| . 2 6 | 3 . 7 | . 9 5 |
|-------+-------+-------|
| . . . | . . . | . . . |
| 6 . 9 | . . 1 | . . . |
| 2 7 4 | . . 9 | . . 1 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site |
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Luke451
Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California
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| Posted: Thu Apr 22, 2010 9:26 pm Post subject: |
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I'm just too dim-witted to figure this out.
If the (49) was not in r5c1, there would be two overlapping URs.
| Code: | *-----------------------------------------------------------------------------*
| 8 6 2 | 79 79 4 | 5 1 3 |
| 7 9 1 | 56 56 3 | 48 48 2 |
| 5 4 3 | 8 1 2 | 9 6 7 |
|-------------------------+-------------------------+-------------------------|
| 349 38 7 | 1 4689 5 | 2348 2348 468 |
|*13+49 *1358 *58 | 49 2 68 | 13478 3478 468 |
| 14 2 6 | 3 48 7 | 148 9 5 |
|-------------------------+-------------------------+-------------------------|
|*13 *1358 *58 | 247 345678 68 | 234678 234578 9 |
| 6 358 9 | 247 34578 1 | 23478 234578 48 |
| 2 7 4 | 56 3568 9 | 368 358 1 |
*-----------------------------------------------------------------------------*
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| Code: | 13 1358 58
13 1358 58
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Do two overlapping URs form a deadly pattern?
Added:
Three cells, four different solutions, as you'd expect w/ two URs.
| Code: | 138 158 315 385
315 385 138 158 |
Here's what I'm trying to do:
Two URs overlap: 13 and 58. Only (49) prevents a double deadly doohickie.
Together with (49)r5c4, the naked pair takes out (4)r5c789 and much damage ensues. |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Fri Apr 23, 2010 12:39 am Post subject: |
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| Luke451 wrote: |
| Code: | 13 1358 58
13 1358 58
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Do two overlapping URs form a deadly pattern?
Three cells, four different solutions, as you'd expect w/ two URs.
| Code: | 138 158 315 385
315 385 138 158 |
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Those four all have an unavoidable set, but there are other solutions. For example ...
... does not have an unavoidable set. |
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Luke451
Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California
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| Posted: Fri Apr 23, 2010 5:03 am Post subject: |
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Drat. 
This opens a ton of questions for me, because I have seen overlapping URs called a DP. I need to figure out when it works and when it doesn't.
When I was trying to figure this out, I said "Where's Ronk when I need him???"
...and here you are.
Thanks! Back to the drawing board...more to come. This is very interesting, at least to me.
Still, you can't have your head handed to you unless you stick your neck out  . |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Fri Apr 23, 2010 8:37 am Post subject: |
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Threw the ?? sink at this initially - but having found the key, you can unlock it in two "basic" steps. (This was not my initial solution path!)
| Quote: | x-wing(8) r57c36
xy-chain: (8=4)r8c9-(4=6)r5c9-(6=8)r5c6-(8=5)r5c3-(5=8)r7c3; r8c2<>8 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 23, 2010 10:58 pm Post subject: |
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| It was an extremely busy grid at the start, but an X-Wing (8) and XY-Wing (468), flightless with pincer transport, did the trick. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Apr 23, 2010 11:18 pm Post subject: |
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Initial VH steps:
| Code: | c36 X-Wing <> 8 r5c9,r57c278,r7c5
c29 X-Wing <> 8 r48c578
r29c45 <56> UR Type 1.2224 r9c5<>56
<68+4> XY-Wing r5c6/r5c9+r6c5 <> 4 r5c4,r6c7
<68+5> XY-Wing r7c6/r7c3+r9c4 <> 5 r7c5
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Leaving a grid that can be cracked with a short XY-Chain or any of four M-Wings starting at r5c6:
| Code: | +-----------------------------------------------------------------------+
| 8 6 2 | 7 9 4 | 5 1 3 |
| 7 9 1 | 56 56 3 | 48 48 2 |
| 5 4 3 | 8 1 2 | 9 6 7 |
|-----------------------+-----------------------+-----------------------|
| 9 38 7 | 1 46 5 | 234 234 468 |
| 134 135 58 | 9 2 68 | 1347 347 46 |
| 14 2 6 | 3 48 7 | 18 9 5 |
|-----------------------+-----------------------+-----------------------|
| 13 135 58 | 24 367 68 | 23467 23457 9 |
| 6 358 9 | 24 357 1 | 2347 23457 48 |
| 2 7 4 | 56 38 9 | 368 358 1 |
+-----------------------------------------------------------------------+
# 62 eliminations remain
XY-Chain: (8=5)r7c3 - (5=8)r5c3 - (8=6)r5c6 - (6=4)r5c9 - (4=8)r8c9 => r8c2<>8
rbb_-r_b- (8=6)r5c6 - r5c9 = (6-8)r4c9 = (8)r6c7 => r6c5<>8
rbr_b-_-r (8=6)r5c6 - r5c9 = (6-8)r4c9 = (8)r4c2 => r5c3<>8
brb_-r_b- (8=6)r5c6 - r4c5 = (6-8)r4c9 = (8)r6c7 => r6c5<>8
brr_b-_-r (8=6)r5c6 - r4c5 = (6-8)r4c9 = (8)r4c2 => r5c3<>8
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Consecutive X-Wings eliminating 14 candidates for <8>. Beautiful.
Note: peterj found that all of my steps aren't necessary. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Apr 23, 2010 11:38 pm Post subject: |
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| Quote: | | XY-Chain: (8=5)r7c3 - (5=8)r5c3 - (8=6)r5c6 - (6=4)r5c9 - (4=8)r8c9 => r8c2<>8 |
Danny, the 8 in r8c2 was what got eliminated by the flightless XY-Wing (468) with pincer transport. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sat Apr 24, 2010 1:01 am Post subject: |
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| Marty R. wrote: | | Danny, the 8 in r8c2 was what got eliminated by the flightless XY-Wing (468) with pincer transport. |
Congratulations! I noticed your X-Wing on <8> and that your second step had a productive elimination at r8c2<>8. I just didn't try to recreate your second step based on the information you provided.
Now that I review my grid above, I see that you could have meant:
#1) XY-Wing <46+8> in r5c9 plus transport in [c3] => r8c2<>8
#2) XY-Wing <46+8> in r5c9 plus transport in [r7] => r8c2<>8
#3) XY-Wing <46+8> in r5c9 plus transport in [b4] => r8c2<>8 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Apr 24, 2010 1:19 am Post subject: |
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| Quote: | Now that I review my grid above, I see that you could have meant:
#1) XY-Wing <46> in r5c9 plus transport in [c3] => r8c2<>8
#2) XY-Wing <46> in r5c9 plus transport in [r7] => r8c2<>8
#3) XY-Wing <46> in r5c9 plus transport in [b4] => r8c2<>8 |
I now notice that the transport could've also been from r8c9 to r7c3, making direct hits on the upper left and lower right of the X-Wing. |
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