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roaa
Joined: 18 Apr 2009
Posts: 112
Location: Sweden
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 Posted: Wed May 14, 2014 9:18 am Post subject: May 14 VH |
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| I used two xyz-wings, 245 and 159. May be there will be some one-stepper too? |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Wed May 14, 2014 10:42 am Post subject: |
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| Code: | *--------------------------------------------------*
| 6 a24 15 | 45-2 3 *149 | 7 149 8 |
| 9 24 7 | 68 b12 68 | 5 14 3 |
| 8 3 15 | 45 159 7 | 2 149 6 |
|----------------+----------------+----------------|
| 1 8 9 | 7 6 2 | 4 3 5 |
| 5 7 2 | 1 4 3 | 8 6 9 |
| 4 6 3 | 9 8 5 | 1 7 2 |
|----------------+----------------+----------------|
| 3 15 6 | 48 c15 48 | 9 2 7 |
| 7 19 8 |c236 129 c169 | 36 5 4 |
| 2 59 4 |c356 7 c69 | 36 8 1 |
*--------------------------------------------------*
1r4c6-(1=2)r2c5
4r4c6-(4=2)r1c2
9r4c6-(9=2)r89c46,r7c5 => -2r1c4; ste |
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hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
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| Posted: Wed May 14, 2014 2:00 pm Post subject: |
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| Code: |
+---------+-------------+----------+
| 6 24 15 | 245 3 149 | 7 149 8 |
| 9 24 7 | 68 12 68 | 5 14 3 |
| 8 3 15 | 45 159 7 | 2 149 6 |
+---------+-------------+----------+
| 1 8 9 | 7 6 2 | 4 3 5 |
| 5 7 2 | 1 4 3 | 8 6 9 |
| 4 6 3 | 9 8 5 | 1 7 2 |
+---------+-------------+----------+
| 3 15 6 | 48 15 48 | 9 2 7 |
| 7 19 8 | 236 129 169 | 36 5 4 |
| 2 59 4 | 356 7 69 | 36 8 1 |
+---------+-------------+----------+
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Play this puzzle online at the Daily Sudoku site
Arkietech said:
| Quote: | 1r4c6-(1=2)r2c5
4r4c6-(4=2)r1c2
9r4c6-(9=2)r89c46,r7c5 => -2r1c4; ste |
Looks great, Dan, but well beyond my pay grade. Could you translate
please?
Hugh |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Wed May 14, 2014 2:51 pm Post subject: |
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| hughwill wrote: | Looks great, Dan, but well beyond my pay grade. Could you translate
please? |
Cell r1c6 must be a 1, 4, or 9
if it is a 1 r2c5 is a 2
if it is a 4 r1c2 is a 2
if it is a 9 either r8c4 or r9c4 is a 2
therefore r1c4 cannot be a 2
Hope this helps. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu May 15, 2014 5:06 am Post subject: Re: May 14 VH |
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| roaa wrote: | | I used two xyz-wings, 245 and 159. May be there will be some one-stepper too? |
I can't see a one-stepper using the standard VH moves. I used a 169 XYZ-Wing followed by another XYZ of 245. An alternative to the second XYZ-Wing is an XY-Wing (14-2), pivoted in r1c6. |
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rmireland
Joined: 21 Sep 2013
Posts: 33
Location: New Orleans
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| Posted: Thu May 15, 2014 5:21 am Post subject: |
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Inspired by arkietech, I saw that a 4 in r1c6 created a contradiction in r1c4: via r1c2 => r1c4 is not 2 but via r1c6 and r3c4, r1c4 cannot be 4 and also r1c4 cannot be 5, so r1c4 must equal 2, the contradiction. Eliminating 4 from the possible list for r1c6 opens an immediate (no intervening basics) 159 xyz in r3c5 that sets r2c5<>1 with ste. Does that count as a one-stepper?
This puzzle also has a two stepper beginning with a fun 125 xy in r2c5 that discovers a naked pair 45 in r13c4 to set r9c4<>5.
Thanks to all for this site and the interesting discussions. |
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hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
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| Posted: Thu May 15, 2014 7:39 pm Post subject: May 14 VH |
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Arkietech said:
Yes it did. Thanks Dan. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu May 15, 2014 11:05 pm Post subject: |
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| Quote: | | This puzzle also has a two stepper beginning with a fun 125 xy in r2c5 that discovers a naked pair 45 in r13c4 to set r9c4<>5. |
I'm having trouble seeing this one. An XY-Wing involving 125 needs three cells: 12, 15 and 25. I don't see a 25 cell in the posted grid.  |
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rmireland
Joined: 21 Sep 2013
Posts: 33
Location: New Orleans
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| Posted: Fri May 16, 2014 4:12 am Post subject: |
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I guess I didn't call it by the right name, but it was closer to any XY wing than anything else I know about.
What I saw was that if you pivot the 1 and 2 in r2c5, the 1 sets r9c4 <> 5 via the 5 in r7c5 while the 2 eliminates the 2 from r1c4, which then leaves r1c4 with 45 and r3c4 with 45, a pair which also sets r9c4 <> 5. That discovered pair takes the place of a single 5 which would remain from a cell with 25 that you were looking for.
I don't recall ever seeing this before in a puzzle, and am not likely to see it again, so it probably doesn't really merit a name of its own. I just thought it was an interesting twist on the standard XY wing.
-Rick |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Fri May 16, 2014 12:05 pm Post subject: |
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| rmireland wrote: | I guess I didn't call it by the right name, but it was closer to any XY wing than anything else I know about.
What I saw was that if you pivot the 1 and 2 in r2c5, the 1 sets r9c4 <> 5 via the 5 in r7c5 while the 2 eliminates the 2 from r1c4, which then leaves r1c4 with 45 and r3c4 with 45, a pair which also sets r9c4 <> 5. That discovered pair takes the place of a single 5 which would remain from a cell with 25 that you were looking for.
I don't recall ever seeing this before in a puzzle, and am not likely to see it again, so it probably doesn't really merit a name of its own. I just thought it was an interesting twist on the standard XY wing.
-Rick |
Using Eureka notation:
(5=1)r7c5-(1=2)r2c5-(2=45)r13c4 => -5r9c4
(2=45)r13c4 is called an (ALS) almost locked set or almost naked pair.
It can be called an ALS XY-WING |
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