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May 14 VH

 
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roaa



Joined: 18 Apr 2009
Posts: 72
Location: Sweden

PostPosted: Wed May 14, 2014 9:18 am    Post subject: May 14 VH Reply with quote

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: 1727
Location: Northwest Arkansas USA

PostPosted: Wed May 14, 2014 10:42 am    Post subject: Reply with quote

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: 208
Location: Birmingham UK

PostPosted: Wed May 14, 2014 2:00 pm    Post subject: Reply with quote

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 |
+---------+-------------+----------+

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: 1727
Location: Northwest Arkansas USA

PostPosted: Wed May 14, 2014 2:51 pm    Post subject: Reply with quote

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: 5162
Location: Rochester, NY, USA

PostPosted: Thu May 15, 2014 5:06 am    Post subject: Re: May 14 VH Reply with quote

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: 15
Location: New Orleans

PostPosted: Thu May 15, 2014 5:21 am    Post subject: Reply with quote

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: 208
Location: Birmingham UK

PostPosted: Thu May 15, 2014 7:39 pm    Post subject: May 14 VH Reply with quote

Arkietech said:
Quote:
Hope this helps.


Yes it did. Thanks Dan.
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Marty R.



Joined: 12 Feb 2006
Posts: 5162
Location: Rochester, NY, USA

PostPosted: Thu May 15, 2014 11:05 pm    Post subject: Reply with quote

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. Question
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rmireland



Joined: 21 Sep 2013
Posts: 15
Location: New Orleans

PostPosted: Fri May 16, 2014 4:12 am    Post subject: Reply with quote

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: 1727
Location: Northwest Arkansas USA

PostPosted: Fri May 16, 2014 12:05 pm    Post subject: Reply with quote

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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