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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Sun Jul 27, 2008 5:13 am Post subject: July27 VH |
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Looks like I'm first. Two strongly connected moves did it.
Quote: | XY-Wing on 56-59-69 and M-Wing on 69. |
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kragzy
Joined: 01 May 2007 Posts: 112 Location: Australia
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Posted: Sun Jul 27, 2008 7:41 am Post subject: |
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I did the usual "cleaning up" with the help of a couple of XY wings and then went back and found an X wing on 9. Possibly the same solution as yours Marty, just from a different angle. |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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Posted: Sun Jul 27, 2008 8:21 am Post subject: |
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It's one of these puzzles again: Easy to mild - with a "vh" twist at the end.
There are many possibilities (including 2 xy-wings and a few m-wings), but I did it with multi-coloring on 4.
Code: |
+--------------------------+--------------------------+--------------------------+
| 57 137 2 | 35 4 8 | 6 17 9 |
| 8 1379 59 | 35 19 6 | 24 17 24 |
| 69 169 4 | 7 19 2 | 3 8 5 |
+--------------------------+--------------------------+--------------------------+
| 469 5 69 | 2 8 7 | 1 3 46 |
| 2 46 7 | 1 3 5 | 9 46 8 |
| 3 8 1 | 4 6 9 | 5 2 7 |
+--------------------------+--------------------------+--------------------------+
| 1 69 3 | 8 25 4 | 7 569 26 |
| 4579 479 8 | 6 25 3 | 24 459 1 |
| 456 2 56 | 9 7 1 | 8 456 3 |
+--------------------------+--------------------------+--------------------------+
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This is the plot of strong links in "4":
Code: |
+·····+·····+·····+
· · · ·
· · · ·
· · ·2---2·
· · ·| |·
· · ·| |·
+·····+·····+|···|+
·*---------------6·
· \ · ·| / ·
· 6-----------6 ·
· | · ·| ·
· | · ·| ·
+··|··+·····+|····+
· | · ·| ·
· | · ·| ·
·o * · ·2 o ·
· · · ·
·*-------------* ·
+·····+·····+·····+
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One of the many possibilities to make a strong/weak/.../strong chain:
start at r9c6.
strong link to r9c1
weak (r9c1 "sees") r4c1
strong to r4c9
weak (r4c9 sees) r2c9 - (the strong link r4c9=r2c9 stands in as a weak link)
strong to r2c7.
Both ends see r8c7 and that solves the puzzle.
Yes, I know that the skyscraper rows 5 and 9 would have been easier ...
There is also a kite (row 5 and col 9) and a skyscraper (cols 3 and 9) in "6" .... |
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keith
Joined: 19 Sep 2005 Posts: 3355 Location: near Detroit, Michigan, USA
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Posted: Sun Jul 27, 2008 11:10 am Post subject: |
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In Nataraj' grid:
An XY-wing 56-59-69 takes out <6> in R9C1.
An extended XY-wing 24-26-46-46-46 takes out <4> in R8C2. This one solves it in one step.
Keith |
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Florida Bob
Joined: 25 Jul 2007 Posts: 12
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Posted: Sun Jul 27, 2008 3:25 pm Post subject: |
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I used a short chain of "9s" in col. 1 & 3 which led to an xy wing in col. 1 that broke the puzzle for me. A nice Sunday exercise. |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Sun Jul 27, 2008 3:28 pm Post subject: |
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Quote: | An extended XY-wing 24-26-46-46-46 takes out <4> in R8C2. This one solves it in one step. |
How are you using the term "Extended XY-Wing"? I thought you used that term for the technique where three identical bivalue calls act as a single XY cell, the technique I learned as "XY-Wing Chain." In this case it seems you've described what I learned as "XY-Wing with pincer coloring.
This whole terminology thing can be very confusing. |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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Posted: Sun Jul 27, 2008 4:44 pm Post subject: |
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I like the term "extended" xy-wing because I can imagine something like this:
Summer. Very hot. Luckily, I have a fan. But, alas, the bed (and thus the fan) is too far away from the socket... What now?
The extension cord, of course!
The xy-wing keith described has both pincers in place: 46 in r5c2 and 42 in r8c7. Unfortunately, the middle cell (26 in r7c9) is too far away from the 46... Good thing there is an extension available: the 46-46 in box 6. It connects the 26 in r7c9 with the 46 in r5c2 and we can rest easy...
I guess in this special case one can see it both ways:
useless 24-26-46 with coloring 46-46 tacked on,
or: 24- (26 - extension 46-46) - 46
Marty R. wrote: | This whole terminology thing can be very confusing. |
Only if you take it serious enough |
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Clement
Joined: 24 Apr 2006 Posts: 1111 Location: Dar es Salaam Tanzania
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Posted: Sun Jul 27, 2008 5:07 pm Post subject: Daily Sudoku: Sun 27- Jul-2008 VH |
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XY-Wing 569, Pivot [5,6]r9c3 with Pincers [6,9]r7c2 and [5,9]r2c3 eliminatng 9 in r23c2 solving the puzzle.
Last edited by Clement on Sun Jul 27, 2008 5:28 pm; edited 1 time in total |
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cgordon
Joined: 04 May 2007 Posts: 769 Location: ontario, canada
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Posted: Sun Jul 27, 2008 5:07 pm Post subject: |
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Using the conjugal pairs of 6's in R57 we can remove the 6 from R9C8 with a Finned X-Wing or from R7C2 with an ER - the end result is the same. There's also an ER that removes 4 from R5C8. |
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keith
Joined: 19 Sep 2005 Posts: 3355 Location: near Detroit, Michigan, USA
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Posted: Sun Jul 27, 2008 5:21 pm Post subject: |
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I guess I've taken to using "extended" for a number of variations. I think various of us use "(pincer) coloring", "extending", and "transporting" to mean the same thing.
Keith |
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tlanglet
Joined: 17 Oct 2007 Posts: 2468 Location: Northern California Foothills
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Posted: Mon Jul 28, 2008 12:15 am Post subject: |
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I missed all the fun! After basics my first find was a finned x-wing in r58c28 that deleted the <4> in r8c7 to finish off the puzzle before it really started.
Ted |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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Posted: Mon Jul 28, 2008 5:47 pm Post subject: |
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tlanglet wrote: | I missed all the fun! After basics my first find was |
Not to worry, Ted. You didn't miss anything. The fun of finding a finned x-wing isn't so bad, is it?
After basics, whatever the first find, it probably solved the puzzle. Why, my grid was so empty already I didn't even think there WOULD be a vh step at all... |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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kragzy
Joined: 01 May 2007 Posts: 112 Location: Australia
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Posted: Tue Jul 29, 2008 1:54 am Post subject: |
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... et vive la difference! |
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cgordon
Joined: 04 May 2007 Posts: 769 Location: ontario, canada
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Posted: Tue Jul 29, 2008 11:22 am Post subject: |
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Conjugal - Conjugate - I see the difference - but with the situation I often end up with in Sudokus - there is a similarity. |
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Deb
Joined: 30 Jun 2008 Posts: 8
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Posted: Sun Aug 03, 2008 7:15 pm Post subject: Can You See This Next Step? |
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This puzzle is giving me palpitations. This is where I got to. My gut kept telling me the next step was in rows 4 & 5 with that cozy mix of 46's but I couldn't figure it out. When I asked for a hint from the computer for the next step it did indeed go straight to row 5 and put a 4 in column 2. Okay. So what was the logic for this? Can anyone help me?
Thanks, Deb
Code: |
+--------------+---------+-----------+
| 57 137 2 | 35 4 8 | 6 17 9 |
| 8 1379 59 | 35 19 6 | 24 17 24 |
| 69 169 4 | 7 19 2 | 3 8 5 |
+--------------+---------+-----------+
| 469 5 69 | 2 8 7 | 1 3 46 |
| 2 46 7 | 1 3 5 | 9 46 8 |
| 3 8 1 | 4 6 9 | 5 2 7 |
+--------------+---------+-----------+
| 1 69 3 | 8 25 4 | 7 569 26 |
| 4579 479 8 | 6 25 3 | 24 459 1 |
| 456 2 56 | 9 7 1 | 8 456 3 |
+--------------+---------+-----------+
| [/code] |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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Posted: Sun Aug 03, 2008 7:45 pm Post subject: Re: Can You See This Next Step? |
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Deb wrote: | This is where I got to. ... it did indeed go straight to row 5 and put a 4 in column 2. Okay. So what was the logic for this? Can anyone help me?
Thanks, Deb
Code: |
+--------------+---------+-----------+
| 57 137 2 | 35 4 8 | 6 17 9 |
| 8 1379 59 | 35 19 6 | 24 17 24 |
| 69 169 4 | 7 19 2 | 3 8 5 |
+--------------+---------+-----------+
| -469 5 69 | 2 8 7 | 1 3 46 |
| 2 4*6 7 | 1 3 5 | 9 4*6 8 |
| 3 8 1 | 4 6 9 | 5 2 7 |
+--------------+---------+-----------+
| 1 69 3 | 8 25 4 | 7 569 26 |
| 4579 479 8 | 6 25 3 | 24 459 1 |
| 4*56 2 56 | 9 7 1 | 8 4*56 3 |
+--------------+---------+-----------+
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Deb, I cannot see a move that immediately takes out the 6 from r5c2.
But there is a skyscraper (4) in rows 5 and 9 that removes 4 from r4c1. That leaves a naked single 4 in r5c2.
----
Since the program cannot do skyscrapers, I really don't know why it gave that hint. Probably a whole series of eliminations ... There is an xy-wing takes out 6 in r9c1, another one takes out 9 in r23c2. A box-line in box 7/col 2 removes 9 from r8c1, which in turn reveals a naked triple 4,5,7 in col 1. This removes 4 from r4c1 and we get that naked single again. Really, the hints are not that obvious sometimes |
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Deb
Joined: 30 Jun 2008 Posts: 8
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Posted: Sun Aug 03, 2008 8:50 pm Post subject: Thanks for trying |
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nataraj, thanks for trying. I guess since I put so much time into trying to find some solution from rows 4 & 5, and since the computer seemed to agree, I was tearing my hair out trying to see it. But I'll look up "skyscraper". Thanks. Deb |
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nataraj
Joined: 03 Aug 2007 Posts: 1048 Location: near Vienna, Austria
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Posted: Sun Aug 03, 2008 9:37 pm Post subject: |
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Deb wrote: | ... since the computer seemed to agree ... |
Deb, one thing to remember about the computer's hints: the program does NOT tell you the next step, but the next solved cell!
It might be that several steps are needed before the next cell is solved.
In contrast to that electronic behaviour, humans usually give the next step (i.e. the next elimination) as a hint. |
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Marty R.
Joined: 12 Feb 2006 Posts: 5770 Location: Rochester, NY, USA
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Posted: Sun Aug 03, 2008 9:45 pm Post subject: |
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I have no idea of what logic the hint used.
Code: | +--------------+---------+--------------+
| 57 137 2 | 35 4 8 | 6 17 9 |
| 8 1379 59 | 35 19 6 | 24 17 24 |
| 69 169 4 | 7 19 2 | 3 8 5 |
+--------------+---------+--------------+
| 469 5 69 | 2 8 7 | 1 3 46b |
| 2 46e 7 | 1 3 5 | 9 46d 8 |
| 3 8 1 | 4 6 9 | 5 2 7 |
+--------------+---------+--------------+
| 1 69 3 | 8 25 4 | 7 569 26a |
| 4579 479 8 | 6 25 3 | 24c 459 1 |
| 456 2 56 | 9 7 1 | 8 456 3 |
+--------------+---------+--------------+ |
A, b and c are an XY-Wing which removes nothing directly. But color pincer b to d and e and the new pincers e and c take out the 4 from r8c2, leaving r5c2 as the only remaining 4 in that column. This is just another way of removing the 4 in r8c2 as the aforementioned skyscraper. |
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