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Oct 31 VH

 
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ZeroAssoluto



Joined: 05 Feb 2017
Posts: 868
Location: Rimini, Italy

PostPosted: Mon Oct 31, 2022 8:54 am    Post subject: Oct 31 VH Reply with quote

Hi everyone,

Code:

+-------+-------------+----------+
| 3 8 2 | 167 67  156 | 4  9  56 |
| 6 4 9 | 28  238 35  | 7  1  25 |
| 7 1 5 | 4   269 69  | 8  3  26 |
+-------+-------------+----------+
| 8 7 6 | 9   1   2   | 5  4  3  |
| 5 2 3 | 67  467 46  | 1  8  9  |
| 4 9 1 | 3   5   8   | 26 26 7  |
+-------+-------------+----------+
| 1 3 4 | 5   26  7   | 9  26 8  |
| 9 5 8 | 26  34  34  | 26 7  1  |
| 2 6 7 | 18  89  19  | 3  5  4  |
+-------+-------------+----------+

Play this puzzle online at the Daily Sudoku site

Quote:
in only one step
if r3c6=6 -6 in r1c456,r3c9
if r3c6=9 r9c5=9 r2c5=8 r2c6=3 r1c6=5 r1c9=6 and -6 in r1c456,r3c9
or
if r1c6=5 -5 in r1c9,r2c6
if r1c6=-5 r2c6=5 r2c5=3 r9c5=8 r3c5=9 r3c9=2 r2c9=5 and -5 in r2c6,r1c9
or
if r2c4=2 -2 in r2c9,r3c5
if r2c4=8 r9c5=8 r3c5=9 r3c9=2 and -2 in r2c9,r3c5
or with 2 steps classical
W-Wing 6,7 in r1c5,r5c4 SL with number 6 in r7c5,r8c4 and -7 in r1c4,r5c5
and
XY-Wing 1,6,9 in r1c4,r39c6 and -1 in r1c6,r9c4


Ciao Gianni
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TomC



Joined: 30 Oct 2020
Posts: 349
Location: Wales

PostPosted: Mon Oct 31, 2022 11:53 am    Post subject: Reply with quote

Remove <6> from r3c6 to solve

Code:

+-------+---------------+------------+
| 3 8 2 | 167 67    156 | 4   9   56 |
| 6 4 9 | 28  238  c35  | 7   1  b25 |
| 7 1 5 | 4   269  x69  | 8   3  a26 |
+-------+---------------+------------+
| 8 7 6 | 9   1     2   | 5   4   3  |
| 5 2 3 | 67  467  e46  | 1   8   9  |
| 4 9 1 | 3   5     8   | 26  26  7  |
+-------+---------------+------------+
| 1 3 4 | 5   26    7   | 9   26  8  |
| 9 5 8 | 26  34   d34  | 26  7   1  |
| 2 6 7 | 18  89    19  | 3   5   4  |
+-------+---------------+------------+

Two ways to look at this:

If x=6, a=2, b=5, c=3 leads to <4> in both d+e
or
XY chain abcde gives pincers of <6> in a + e to remove <6> from x
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Mon Oct 31, 2022 1:35 pm    Post subject: Reply with quote

I used the 269 XYZ-Wing r3c56,r7c5 (-6r1c5) which opened up the 69-1 XY-Wing r1c4,r39c6 (-1r1c6, -1r9c4).
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TomC



Joined: 30 Oct 2020
Posts: 349
Location: Wales

PostPosted: Tue Nov 01, 2022 1:31 pm    Post subject: Reply with quote

You can make the same eliminations as the 69-1 XY-wing but not use the XYZ-wing first

Code:

+-------+------------------+------------+
| 3 8 2 | a167 b67    x156 | 4   9   56 |
| 6 4 9 |  28   238    35  | 7   1   25 |
| 7 1 5 |  4    269   c69  | 8   3   26 |
+-------+------------------+------------+
| 8 7 6 |  9    1      2   | 5   4   3  |
| 5 2 3 |  67   467    46  | 1   8   9  |
| 4 9 1 |  3    5      8   | 26  26  7  |
+-------+------------------+------------+
| 1 3 4 |  5    26     7   | 9   26  8  |
| 9 5 8 |  26   34     34  | 26  7   1  |
| 2 6 7 | x18   89    d19  | 3   5   4  |
+-------+------------------+------------+


If x=1, ab=<67>, c=9, d=1

Or using c as the pivot
if c=6, b=7, a=1
if c=9, d=1

This gives pincers on <1> in a+d to remove <1> from x
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Tue Nov 01, 2022 9:09 pm    Post subject: Reply with quote

Hi Gianni! When you said 'classical steps' I thought that you were referring to just VH moves because many years ago Marty told me that every VH puzzle on this site could be solved by using just the 3 classical wing moves X-Wing, XY-Wing, and XYZ-Wing. Since then I have only considered using VH moves when solving any VH puzzle on this site. When I suggested to Marty that we refer to this as the 'official solution' he really didn't like it and suggested instead that we refer to it as the 'standard solution'. I like his suggestion.
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