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Feb 16 not VH at all

 
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TomC



Joined: 30 Oct 2020
Posts: 349
Location: Wales

PostPosted: Tue Feb 16, 2021 8:11 am    Post subject: Feb 16 not VH at all Reply with quote

Code:

+----------------+-----------------+-----------------+
| 379 479 23479  | 234   1    8    | 2379  5    6    |
| 356 36  235    | 7     9    256  | 1238  138  4    |
| 8   1   234579 | 2346  234  2456 | 2379  37   239  |
+----------------+-----------------+-----------------+
| 379 5   6      | 12348 2348 124  | 13789 1378 1389 |
| 2   38  1      | 9     5    7    | 4     6    38   |
| 379 479 34789  | 13468 348  146  | 5     2    1389 |
+----------------+-----------------+-----------------+
| 356 368 358    | 1248  248  124  | 1238  9    7    |
| 4   79  79     | 128   6    3    | 128   18   5    |
| 1   2   38     | 5     7    9    | 6     4    38   |
+----------------+-----------------+-----------------+

Play this puzzle online at the Daily Sudoku site

At this point still basics to do, but using the 38 pairs in r59 -8 in r5c9 and r6c3


Last edited by TomC on Tue Feb 16, 2021 1:19 pm; edited 1 time in total
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Tue Feb 16, 2021 12:29 pm    Post subject: Reply with quote

I also solved it using just basics so I'm guessing that this one is rated wrong. My beginning basics took me to the following grid:
Code:
+---------------+----------------+------------+
| 79  479 2479  | 234   1    8   | 379  5  6  |
| 56  36  235   | 7     9    25  | 18   18 4  |
| 8   1   4579  | 346   34   456 | 379  37 2  |
+---------------+----------------+------------+
| 39  5   6     | 12348 2348 124 | 378  37 19 |
| 2   38  1     | 9     5    7   | 4    6  38 |
| 379 479 34789 | 1368  38   16  | 5    2  19 |
+---------------+----------------+------------+
| 56  368 358   | 1248  248  124 | 1238 9  7  |
| 4   79  79    | 128   6    3   | 128  18 5  |
| 1   2   38    | 5     7    9   | 6    4  38 |
+---------------+----------------+------------+

And then at this point I used the 3's Locked Candidates in column 1 to solve it.

Hey Tom, You might want to put a '?' after the 'VH' in the title of this post to indicate that it's not really a VH (unless you and I are missing something?)
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peter urhegyi



Joined: 26 Oct 2020
Posts: 27

PostPosted: Tue Feb 16, 2021 4:02 pm    Post subject: 16/02/2021 Daily very hard? Reply with quote

I solved it with the 2 3's at R35C1. One of them must be 3 so R5C2=8. But if you like a very hard step, which is not needed, there's a skyscraper (also remote pair or even w-wing) at R59 linked by two 8's at column 9 or by two 3's(it's a dual one) so all cell's which can see both R5C2 and R9C3 can't be 3 and can't be 8. R6C3<>3/8 and R7C2<>3/8 so R7C2 must be 6!
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Tue Feb 16, 2021 4:27 pm    Post subject: Re: 16/02/2021 Daily very hard? Reply with quote

peter urhegyi wrote:
I solved it with the 2 3's at R35C1. One of them must be 3 so R5C2=8. But if you like a very hard step, which is not needed, there's a skyscraper (also remote pair or even w-wing) at R59 linked by two 8's at column 9 or by two 3's(it's a dual one) so all cell's which can see both R5C2 and R9C3 can't be 3 and can't be 8. R6C3<>3/8 and R7C2<>3/8 so R7C2 must be 6!


Hi Peter, The 3's in r35c1 that you used are the 3's 'Locked Candidates' that I mentioned! That's exactly how locked candidates work! By the way, I looked at the grid that I posted to see if I could find what VH move the software might have used instead of simply using the LC's but I couldn't. (I did notice the 18 UR but that's not a VH move.)
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peter urhegyi



Joined: 26 Oct 2020
Posts: 27

PostPosted: Tue Feb 16, 2021 7:14 pm    Post subject: Re: 16/02/2021 Daily very hard? Reply with quote

Quote:
Hi Peter, The 3's in r35c1 that you used are the 3's 'Locked Candidates' that I mentioned! That's exactly how locked candidates work! By the way, I looked at the grid that I posted to see if I could find what VH move the software might have used instead of simply using the LC's but I couldn't. (I did notice the 18 UR but that's not a VH move.)

I have found a swordfish in R259 C239 which eliminates R6C3<>3 and R7C23<>3, so R9C3 must be 3!
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Tue Feb 16, 2021 9:08 pm    Post subject: Re: 16/02/2021 Daily very hard? Reply with quote

peter urhegyi wrote:
Quote:
Hi Peter, The 3's in r35c1 that you used are the 3's 'Locked Candidates' that I mentioned! That's exactly how locked candidates work! By the way, I looked at the grid that I posted to see if I could find what VH move the software might have used instead of simply using the LC's but I couldn't. (I did notice the 18 UR but that's not a VH move.)

I have found a swordfish in R259 C239 which eliminates R6C3<>3 and R7C23<>3, so R9C3 must be 3!

Hi Peter! Interesting! I also saw that you mentioned a skyscraper and w-wing. All of the VH puzzles on this site can be solved using just X-wings, XY-wings, and/or XYZ-wings so there must have been one of those types of wings available in order to confuse the software into thinking that it was necessary and caused the puzzle to be rated incorrectly.
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peter urhegyi



Joined: 26 Oct 2020
Posts: 27

PostPosted: Tue Feb 16, 2021 9:46 pm    Post subject: Reply with quote

The swordfish is the three rows/columns equivalent of the x-wing with only two rows/columns. I've looked to a few daily puzzles published in the last years and found only two of them where swordfishes were necessary or could help to solve. Because it's a VH move I hope to see more of them in future puzzles.
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Earl



Joined: 30 May 2007
Posts: 677
Location: Victoria, KS

PostPosted: Wed Feb 17, 2021 2:43 am    Post subject: Feb 16VH Reply with quote

I am confused by this discussion.

I was under the impression that moves such as UR, W-wing, skyscraper, etc. are beyond “basic” and are VH moves.

Please clarify criteria and sources.

Early Earl
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TomC



Joined: 30 Oct 2020
Posts: 349
Location: Wales

PostPosted: Wed Feb 17, 2021 7:53 am    Post subject: Reply with quote

Surely, if a puzzle can be solved with VH moves, it doesn't make it a VH puzzle if it can be solved with basic moves

I'm sure there are many easy puzzles that can be solved with VH moves
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hughwill



Joined: 05 Apr 2010
Posts: 422
Location: Birmingham UK

PostPosted: Wed Feb 17, 2021 10:54 am    Post subject: 16 Feb 'VH' Reply with quote

It wasn't VH

It happens from time to time on this algorithm.

I've though about looking at examples to see what the common factor is, but I have decided that life is too short.
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Wed Feb 17, 2021 11:46 am    Post subject: Re: Feb 16VH Reply with quote

Earl wrote:
I am confused by this discussion.

I was under the impression that moves such as UR, W-wing, skyscraper, etc. are beyond “basic” and are VH moves.

Please clarify criteria and sources.

Early Earl

Hi Earl, Those moves that you mentioned are more complicated than the 3 wings that are considered VH moves by this site so they're actually VH+ moves! Every VH puzzle on this site should be able to be solved by just using the 3 types of wings (X, XY, and XYZ) and they're supposed to always require the use of at least one of them to be rated VH.
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Wed Feb 17, 2021 12:17 pm    Post subject: Reply with quote

I forgot to mention that since every VH on this site can be solved just using the 3 wings (i.e. X, XY, and XYZ), I suggested to Marty a long time ago that we call solutions using just these moves the 'official solution'. Marty suggested instead we call it the 'standard solution'! Great idea I think! Any solution using just the 'standard' VH moves is a 'standard solution' but all other solutions are welcome as well of course!
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