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April 29 VH
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Tue Apr 29, 2008 6:21 am    Post subject: April 29 VH Reply with quote

Today's puzzle offers ample oppurtunities to use different methods.

It takes a little while to arrive here:


+--------------------------+--------------------------+--------------------------+
| 37 2 478 | 1 389 6 | 3579 489 3589 |
| 9 6 78 | 38 4 5 | 37 1 2 |
| 1 348 5 | 7 2389 29 | 6 489 389 |
+--------------------------+--------------------------+--------------------------+
| 5 89 2 | 6 89 1 | 4 3 7 |
| 4 7 89 | 38 23589# 29 | 59 6 1 |
| 6 1 3 | 59# 7 4 | 2 89 589 |
+--------------------------+--------------------------+--------------------------+
| 23 345 6 | 24 59 8 | 1 7 39 |
| 8 35 1 | 59 6 7 | 3-9 2 4 |
| 27 49 479 | 24 1 3 | 8 5 6 |
+--------------------------+--------------------------+--------------------------+



For those who like coloring, some kite options:
(3) col 1, row 8
(9) col 4, row 7

For the wing lovers:
xy-wing boxes 1 and 2
xyz-wing col 5

And (not sure if this is really) a w-wing: two pincers 59 (r5c7 and r8c4), connected by a strong link on 5 in box 5 (#), removing 9 from r8c7.


Last edited by nataraj on Wed Apr 30, 2008 6:07 pm; edited 2 times in total
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andras



Joined: 31 Oct 2007
Posts: 56
Location: Mid Wales

PostPosted: Tue Apr 29, 2008 6:38 am    Post subject: Reply with quote

I thought this was going to be a stinker, but in the end the simple xy on 3,7,8 (pivot at R2C3) broke it, though it took me a little while to realise it and I thought there must be something else in there!

But there wasn't! Smile

John
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Tue Apr 29, 2008 2:40 pm    Post subject: Reply with quote

Many variations to solve this one. I used coloring on <5> to delete that candidate at r6c9 which solved the puzzle.

Ted
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

PostPosted: Tue Apr 29, 2008 3:44 pm    Post subject: Reply with quote

I used a 78-73-83 XY-Wing, Remote Pairs on 89 and finished it off with a W-Wing on 59. However, I think I had another 59 cell that was used that doesn't show in nataraj's grid. And I do believe that nataraj's W-Wing is indeed a valid one.
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stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Tue Apr 29, 2008 6:13 pm    Post subject: Reply with quote

OK, so I saw the same 37-78-38 XY-Wing that everybody else saw in rows 1 and 2...however, the "stevieboy" method eliminated the '7' in R1C3...what the heck did I do wrong??
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Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Tue Apr 29, 2008 7:00 pm    Post subject: Reply with quote

Hi stevieboy,

Let's make sure you are clear on the XY Wing fundamentals. It is a good idea to identify which cell is the pivot. It is the one that can "see" the other two (the "pincers") which must not be able to "see" each other.

Here, the {37} in r1c1 can only see the {78} in r2c3 (they both share box 1). And, the {38} in r2c4 can also only see the {78} in r2c3 (they share row 2). Since the {78} can see the other two cells, it is the pivot. The {37} and {38} cannot see each other, so we have an XY Wing and they are the pincers.

The pincer digit that makes the eliminations is the one which is NOT in the pivot. So, here it is those <3>s in r1c1 and r2c4. Any <3> that can see both of these is eliminated. Here, there is only one such <3>, in r1c5.

The reasoning: If the pivot is <7>, pincer r1c1 must be <3>. If the pivot is <8>, pincer r2c4 must be <3>. Since those are the only two possibilities, one or both of the pincers must be <3> and any cell that sees both of them cannot be.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Apr 29, 2008 7:14 pm    Post subject: Reply with quote

trying to be a good sport and using the draw/play, I got to this point. don't expect all basics to be filtered out.

Code:
.---------------------.---------------------.---------------------.
|#37     2      478   | 1     -389    6     | 3579   489    3589  |
| 9      6     #78    |#38     4      5     | 37     1      2     |
| 1      348    5     | 7      2389   29    | 6      489    389   |
:---------------------+---------------------+---------------------:
| 5      89     2     | 6      89     1     | 4      3      7     |
| 4      7      89    | 38     23589  29    | 59     6      1     |
| 6      1      3     | 59     7      4     | 2      89     589   |
:---------------------+---------------------+---------------------:
| 23     345    6     | 24     59     8     | 1      7      39    |
| 8      35     1     | 59     6      7     | 39     2      4     |
| 27     49     479   | 24     1      3     | 8      5      6     |
'---------------------'---------------------'---------------------'


this is where I saw the marked xy-wing on {3,7,8} which created a naked pair on {8,9} in col 5...

and it was solved.
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stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Tue Apr 29, 2008 7:47 pm    Post subject: Reply with quote

Asellus, a brilliant explanation! Thank you so much...I will cut and paste, and file away.

BTW, I used to live in Marin County, just down the road from you!

storm_norm, yes, that naked pair eliminates the all of the other <8> down col. 5...leaving the <2> naked pair, as well.

YES, after all that, the whole shabang got solved right away!

You guys are really helping me out!!! The "pair-links" (or, whatever they're called) connecting between boxes is something that I'll be investigating as we go along - questions will be forthcoming as those days go by.

THANKS ALL!
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stevieboy



Joined: 25 Jan 2008
Posts: 31
Location: Michigan

PostPosted: Tue Apr 29, 2008 7:50 pm    Post subject: Reply with quote

hmmm...my quote to storm_norm didn't come out right....I really did have naked pairs mentioned in there!
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Apr 29, 2008 7:51 pm    Post subject: Reply with quote

nataraj wrote:
Quote:
For those who like coloring, some kite options:
(3) col 1, row 8
(9) col 4, row 7

For the wing lovers:
xy-wing boxes 1 and 2
xyz-wing col 5

And (not sure if this is really) a w-wing: two pincers 59 (r5c7 and r8c4), connected by a strong link on 5 in box 5 (#), removing 9 from r8c7.


don't forget the {2,9} UR in r35c56 removes the 9's in r35c5
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montalbano1944



Joined: 26 Apr 2008
Posts: 6

PostPosted: Tue Apr 29, 2008 9:49 pm    Post subject: Reply with quote

After the basics, an XY wing (378) with pivot at R2C3 removes the 3 from R1C5, and that does it.
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Tue Apr 29, 2008 9:53 pm    Post subject: Reply with quote

A strange one – I never felt I’d gone far enough with the basics. I found 4 of my favourite ERs but still needed the xy wing - and it would seem that's all I needed.

Could I ask why many of the posted grids I see on this Forum (incl the ones from Nataraj & Storm Norm above) have the numbers squished and unreadable on the left-hand side. (it's like 6 columns compressed into 3). Is that my fault?? I'm very computer literate but maybe my screen is too small. Maybe it's my mouse?
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Tue Apr 29, 2008 10:54 pm    Post subject: Reply with quote

Never had this problem, neither with linux/windows nor with firefox/internet explorer. What OS, browser and graphical resolution do you have ?
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Tue Apr 29, 2008 11:51 pm    Post subject: Reply with quote

cgordon wrote:
Could I ask why many of the posted grids I see on this Forum (incl the ones from Nataraj & Storm Norm above) have the numbers squished and unreadable on the left-hand side. (it's like 6 columns compressed into 3). Is that my fault?? I'm very computer literate but maybe my screen is too small. Maybe it's my mouse?


Craig, could you please take a screenshot or (if you are on Vista already) use the "snipping tool" and upload the image so I can take a look at the "compressed" view? I don't remember having any problem with viewing the posts, but that may result from using "firefox". I remember sheryl posting about problems viewing our grids a while ago.
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Tue Apr 29, 2008 11:54 pm    Post subject: Reply with quote

Today's puzzle offered me NO opportunities to resolve it. I have finally quit, and decided to throw the towel in. I will now look (backward) to see how you wizards did this.
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crunched



Joined: 05 Feb 2008
Posts: 168

PostPosted: Wed Apr 30, 2008 12:07 am    Post subject: Reply with quote

Weird. I found the xy-wing that everybody said was the key. I still could not go anywhere after that. Yes I found the naked 89s in column 5 too. But that resulted in a combination of 2-3-5 in column five, and I could not go anywhere after that.
I will run through this and see if I have made a mistake. Mistakes can kill a solution.
In the meantime, those who know what to do after the 3-7-8 xy-wing, removing the 3 in r1, c5, please help me.
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cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Wed Apr 30, 2008 12:29 am    Post subject: Reply with quote

Quote:
Never had this problem, neither with linux/windows nor with firefox/internet explorer. What OS, browser and graphical resolution do you have ?

Quote:
Craig, could you please take a screenshot or (if you are on Vista already) use the "snipping tool" and upload the image so I can take a look at the "compressed" view? I don't remember having any problem with viewing the posts, but that may result from using "firefox".


To my good mates Ravel and Nataraj!! I've already come to know you are very helpful guys - but hey!! .. Linux - firefox - OS, browser - graphical resolution - screenshot -snipping tool and upload compressed view. What the ????

I've got Internet Explorer eh. Sorry - don't understand anything else.
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Wed Apr 30, 2008 6:50 am    Post subject: Reply with quote

cgordon wrote:
I've got Internet Explorer eh. Sorry - don't understand anything else.


... and maybe I'll yet find someone who understands Internet Explorer ...

I believe this is what the "squished" grid looks like.
The top window in this screenshot shows how Internet Explorer (IE) handles text that is too wide to fit into its presentation window: Internet Explorer breaks "long words", in our case the "+-----+----" lines in order to fit everything into the window. If you look closely you will see there is no scroll bar at the bottom of the IE window

In contrast, Firefox (another web browser, lower window) shows only the leftmost portion of the text and lets the user slide the window left and right.


Two simple methods to see the grids correctly:

a) use full screen and a font size small enough for the grid to fit onto the screen

b) mark the grid with the mouse, copy and paste it into Windows editor (simply create a new .txt document on your desktop and double click it. Make sure you have Format...Word wrap off )


Last edited by nataraj on Wed Apr 30, 2008 5:24 pm; edited 1 time in total
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Wed Apr 30, 2008 6:57 am    Post subject: Reply with quote

crunched wrote:
Weird. I found the xy-wing that everybody said was the key. I still could not go anywhere after that. Yes I found the naked 89s in column 5 too. But that resulted in a combination of 2-3-5 in column five, and I could not go anywhere after that.
I will run through this and see if I have made a mistake. Mistakes can kill a solution.
In the meantime, those who know what to do after the 3-7-8 xy-wing, removing the 3 in r1, c5, please help me.


With the NP 89 in col 5, r7c5 becomes a naked single 5. Probably your grid is not yet reduced
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nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Wed Apr 30, 2008 6:00 pm    Post subject: Reply with quote

I've changed the formatting in my initial post, from BBCode "code" to HTML "pre". It should now display un-squished even in small windows.

But I like the appearance with "code" much more, plus it is much much easier to just hit the code button than to remember and type in proper HTML tags.

The blank lines are just horrible.

Therefore I don't think I'll xx to the new format, sorry.

Sad
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