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Jul 16 VH

 
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 942
Location: Rimini, Italy

PostPosted: Fri Jul 16, 2021 8:25 am    Post subject: Jul 16 VH Reply with quote

Hi everyone,

Code:

+----------+-------------+------------+
| 7  6 8   | 49  2   49  | 5    3  1  |
| 15 4 159 | 356 7   356 | 69   8  2  |
| 2  3 59  | 1   56  8   | 4679 67 49 |
+----------+-------------+------------+
| 6  8 7   | 2   459 45  | 3    1  59 |
| 15 2 15  | 367 69  36  | 79   4  8  |
| 4  9 3   | 57  8   1   | 2    57 6  |
+----------+-------------+------------+
| 9  1 2   | 8   45  7   | 46   56 3  |
| 8  5 4   | 69  3   69  | 1    2  7  |
| 3  7 6   | 45  1   2   | 8    9  45 |
+----------+-------------+------------+

Play this puzzle online at the Daily Sudoku site

Quote:
W-Wing 4,5 in r4c6,r9c4 SL with number 4 in r1c46 and -5 in r6c4
or
XY-Wing 6,7,9 in r25c7,r3c8 and -7 in r3c7,r6c8
or
XY-Wing 4,6,9 in r27c7,r3c9 and -4 in r3c7,r9c9
or
Skyscraper with number 5 in r6c48,r9c49 and -5 in r4c9,r7c8
or
Skyscraper with number 5 in r6c48,r7c58 and -5 in r4c5,r9c4
or
UR 1,5 in r25c13 and r2c3=9
or
2 String Kite with number 5 in r9c49,r67c8 and -5 in r6c4
or
2 String Kite with number 5 in r6c48,r49c9 and -5 in r9c4


Ciao Gianni
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri Jul 16, 2021 7:09 pm    Post subject: Warped x wing ? Reply with quote

OK, so I think Gianni got most of the VH techniques. ✔️

While trying to stay within the VH world I noticed a weird effect.

There is an incomplete x wing at r49 c49 on 5's. perfectly good until you get to the square r4c4 which is already filled in and is 2. Stops the x wing. Or does it ?

Right next to that completed 2, are two squares both with 5 in them. R4c56.

Now, if either of these is TRUE then r6c4<>5.

If both of these are FALSE then r4c9 is TRUE and r9c9 is FALSE and r9c4 is TRUE
which means r6c4<>5.

A sort of offbeat x-wing.
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 942
Location: Rimini, Italy

PostPosted: Fri Jul 16, 2021 10:12 pm    Post subject: Reply with quote

Hi everyone,

this is a Finned X-Wing, Finned Sashimi variant.

Ciao Gianni
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri Jul 16, 2021 10:47 pm    Post subject: Reply with quote

Thanks for the official name Gianni. I have only ever heard sashimi before with reference to swordfish. First time I have used a displaced x wing.
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sat Jul 17, 2021 12:26 pm    Post subject: Reply with quote

Been playing a long time and this is a first for me. I guess it must be a rare structure. I get the “fin” because there is an extra 5 which actually plays no part because the “displaced” 5 acts like a fin anyway. Sashimi because it is a whittled down or incomplete - as per the swordfish that is missing candidates in the expected positions but still makes eliminations.
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TomC



Joined: 30 Oct 2020
Posts: 358
Location: Wales

PostPosted: Sat Jul 17, 2021 1:29 pm    Post subject: Reply with quote

My solution would be r5c7<>9 using the 69 in r2c7 and r5c5 would mean no 6's in box 2

I would love this to have an exotic name!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sat Jul 17, 2021 2:16 pm    Post subject: Reply with quote

Nice one Tom.

One way of describing what you have there is a nice xy chain.The chain links the two <69> cells you describe.

Essentially, either the 9 in r2c7 is true or the 9 in r5c5 is true. They are the pincer cells that make r5c7<>9.
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sat Jul 17, 2021 3:24 pm    Post subject: Reply with quote

TomC wrote:


I would love this to have an exotic name!


I like your solve method - "Tom's House Of Contradictions". Cool
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TomC



Joined: 30 Oct 2020
Posts: 358
Location: Wales

PostPosted: Sat Jul 17, 2021 5:29 pm    Post subject: Reply with quote

Love it!

This method also solves your recent 2007 revisit

r8c5<>12 as then no 1's or 2's in box 2
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sat Jul 17, 2021 8:16 pm    Post subject: Reply with quote

Tidy.
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