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yeoks
Joined: 16 May 2010
Posts: 33
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 Posted: Tue Dec 11, 2012 10:15 am Post subject: Dec 11 VH |
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After basics
| Code: |
+------------+----------------------+---------------+
| 37 36 8 | 3579 1 3579 | 257 269 4 |
| 1 46 59 | 45789 4579 2 | 578 3 69 |
| 347 2 59 | 6 34579 345789 | 578 189 19 |
+------------+----------------------+---------------+
| 25 179 4 | 2579 25679 1579 | 3 267 8 |
| 25 17 3 | 24578 24567 14578 | 9 2467 256 |
| 8 79 6 | 234579 234579 34579 | 1 247 25 |
+------------+----------------------+---------------+
| 34 8 17 | 2479 2479 6 | 24 5 1239 |
| 6 5 2 | 1 349 349 | 48 89 7 |
| 9 34 17 | 2457 8 457 | 6 12 123 |
+------------+----------------------+---------------+
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I need 2 steps to solve.
XYZ Wing 189 pivoted at r3c8; r1c8 <>9 followed by
XY Wing 23-4 pivoted at r9c9; r7c1<>4 |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Tue Dec 11, 2012 11:23 am Post subject: another almost xy |
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this is a 1 stepper after only3 numbers have been entered!
If r9c9 <>1 then xy 234 pivoted at r7c7 sets r9c2 =4 else if r9c9 =1 simple eliminations lead to r9c2 =4
so r9c2 = 4 and this solves it |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Tue Dec 11, 2012 12:36 pm Post subject: |
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The first step solves it.
| Code: |
*-----------------------------------------------------------------------------*
| 37 36 8 | 3579 1 3579 | 257 269 4 |
| 1 46 59 | 45789 4579 2 | 578 3 69 |
| 347 2 59 | 6 34579 345789 | 578 189 19 |
|-------------------------+-------------------------+-------------------------|
| 25 179 4 | 2579 25679 1579 | 3 267 8 |
| 25 17 3 | 24578 24567 14578 | 9 2467 256 |
| 8 79 6 | 234579 234579 34579 | 1 247 25 |
|-------------------------+-------------------------+-------------------------|
|a34 8 17 | 2479 2479 6 |b24 5 129-3 |
| 6 5 2 | 1 349 349 | 48 89 7 |
| 9 4-3 17 | 2457 8 457 | 6 c12 c123 |
*-----------------------------------------------------------------------------*
(3=4)r7c1-(4=2)r7c7-(2=3)r9c89 => -3r7c9,r9c2; stte |
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hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
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| Posted: Tue Dec 11, 2012 12:50 pm Post subject: Dec 11 VH |
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| Quote: | | if r9c9 =1 simple eliminations lead to r9c2 =4 |
George- If r9c9=1 then surely r9c2 has the only remaining 3 on the row....or
have I as usual misunderstood?
Dan- Is there a name for your pseudo XY wing?
Hugh |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Tue Dec 11, 2012 1:50 pm Post subject: Re: Dec 11 VH |
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| hughwill wrote: | Dan- Is there a name for your pseudo XY wing?
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Yes it is an als xy-wing -- remove the 2 from column 89 of row 9 and it forces r9c8 =1 and r9c9=3. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Tue Dec 11, 2012 2:22 pm Post subject: Re: Dec 11 VH |
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| hughwill wrote: | | Quote: | | if r9c9 =1 simple eliminations lead to r9c2 =4 |
George- If r9c9=1 then surely r9c2 has the only remaining 3 on the row....or
have I as usual misunderstood?
Dan- Is there a name for your pseudo XY wing?
Hugh |
No not quite a misunderstanding but the reasoning below that denies the 1 smacks of "trial and error"
If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 ....... |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Dec 11, 2012 3:17 pm Post subject: |
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| It's my personal preference to limit myself to the standard VH moves on these puzzle and I needed two of them: XYZ-Wing on 189 pivoted in r3c8 and the XY-Wing on 243 pivoted in r7c7. Interesting puzzle, as the large number of polyvalue cells required care as well. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Dec 11, 2012 4:05 pm Post subject: |
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| Quote: | | If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 ....... |
By the way, Ted uses this type of move and calls it an Almost XY-Wing, or AXY. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Tue Dec 11, 2012 6:37 pm Post subject: |
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| Marty R. wrote: | | Quote: | | If r9 is 1 then as you say r9c2 is 3 BUT also it must be a 4 since solving 124 in Block 9 forces r9c2 to be 4 so this shows that it can't be 1 and the simple xy wing now says that r9c2 is 4 ....... |
By the way, Ted uses this type of move and calls it an Almost XY-Wing, or AXY. |
A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.
I would prefer "almost" since the fish people have their definition of what a fin is.
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Dec 11, 2012 7:16 pm Post subject: |
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| keith wrote: |
A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.
I would prefer "almost" since the fish people have their definition of what a fin is.
Keith |
I remember it well, the first example of what was called a "Finned" XY-Wing, which seems appropriate. However, Ted is the leading user and he uses "Almost", so that's how I now refer to it. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Tue Dec 11, 2012 8:46 pm Post subject: |
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| Marty R. wrote: | | keith wrote: |
A while ago we played with this and called it a finned XY-wing, the idea being that an extra digit in an XY-wing is a fin.
I would prefer "almost" since the fish people have their definition of what a fin is.
Keith |
I remember it well, the first example of what was called a "Finned" XY-Wing, which seems appropriate. However, Ted is the leading user and he uses "Almost", so that's how I now refer to it. |
Here is the original thread, which refers to others:
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?p=12552
Very interesting reading!
No offense to current participants, but I miss Asellus and Nataraj!
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Dec 12, 2012 1:40 am Post subject: |
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| Quote: | Very interesting reading!
No offense to current participants, but I miss Asellus and Nataraj! |
Interesting indeed.
I miss those two guys as well. I've been active on various forums ever since I got my first computer 13 years ago and if there's one constant, it's that people come and go.
When I first joined here almost seven years ago the cast of characters was different; you might be the only one still left. There was David Bryant of DIC fame who was the most prolific poster until he dropped out and I eventually took over that unfortunate "honor."
There was Tracy, Ravel, Steve, and dozens of others who don't come to mind. Sam even posted in those days!
Nothing stays the same. |
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hughwill
Joined: 05 Apr 2010
Posts: 424
Location: Birmingham UK
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| Posted: Wed Dec 12, 2012 4:44 pm Post subject: Dec 11 VH |
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| Quote: | | I miss those two guys as well. I've been active on various forums ever since I got my first computer 13 years ago and if there's one constant, it's that people come and go. |
If it's any solace, Nataraj posted on 'other puzzles' today (to celebrate 12.12.12). However Assellus stopped suddenly(?) just over a year ago...
Tout ca change, tout c'est la meme chose. |
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