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VH+ 040322

 
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immpy



Joined: 06 May 2017
Posts: 570

PostPosted: Sun Apr 03, 2022 5:36 pm    Post subject: VH+ 040322 Reply with quote

Hello all, enjoy the puzzle.

Code:

+-------+-------+-------+
| . . 6 | . 2 . | 7 . 3 |
| . . 8 | 5 . . | . . . |
| 4 2 . | . . . | . . 6 |
+-------+-------+-------+
| . 5 . | . 3 2 | . . . |
| 1 . . | 6 . 4 | . . 9 |
| . . . | 7 9 . | . 6 . |
+-------+-------+-------+
| 8 . . | . . . | . 4 1 |
| . . . | . . 5 | 6 . . |
| 7 . 3 | . 4 . | 9 . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

cheers...immp
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Mon Apr 04, 2022 3:55 pm    Post subject: Reply with quote

Thanks for the puzzle immpy! Here's the grid after basics:
Code:
+-------------+------------------+------------------+
| 5   19   6  | 4     2    189   | 7      189   3   |
| 39  37   8  | 5     167  1679  | 124    129   24  |
| 4   2    17 | 1389  178  13789 | 158    1589  6   |
+-------------+------------------+------------------+
| 6   5    9  | 18    3    2     | 148    178   478 |
| 1   378  27 | 6     5    4     | 238    238   9   |
|g23 f38   4  | 7     9   e18    | 12358  6     258 |
+-------------+------------------+------------------+
| 8  i69   5  | 239   67   3679  | 23     4     1   |
|h29  4   b12 | 1389 c18   5     | 6      378   78  |
| 7  a16*  3  | 128   4   d168   | 9      258   258 |
+-------------+------------------+------------------+

And then I used the following chain: (6*-1)r9c2=r8c3-(1=8)r8c5-(6*8=1)r9c6-(1=8)r6c6-(8=3)r6c2-(3=2)r6c1-(2=9)r8c1-(9=6)r7c2 contradiction => r9c2 <> 6; stte.
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Thu Apr 07, 2022 1:26 pm    Post subject: VH + 040322 Reply with quote

Code:

+-------------------+------------------------+------------------------+
| 5      19      6  | 4        2       189   | 7         189      3   |
|e39    d37      8  | 5      cb167   cb1679  | 124       129      24  |
| 4      2       17 | 1389     178     13789 | 158       1589     6   |
+-------------------+------------------------+------------------------+
| 6      5       9  | 18       3       2     | 148       178      478 |
| 1      378     27 | 6        5       4     | 238       238      9   |
| 23     38      4  | 7        9       18    | 12358     6        258 |
+-------------------+------------------------+------------------------+
| 8    ga6-9     5  | 239     b67     b3679  | 23        4        1   |
|f29     4       12 | 1389     18      5     | 6         378      78  |
| 7      16      3  | 128      4       168   | 9         258      258 |
+-------------------+------------------------+------------------------+

(6)r7c2 = Type 4 UR(67)r27c56 – (7)r2c56 = (7-3)r2c2 = (3-9)r2c1 = r8c1 – (9)r7c2 => - 9r7c2; stte
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri Apr 08, 2022 2:22 pm    Post subject: Reply with quote

Very nice Clement. I like the way that your loop causes then pirouettes into the UR and back round again.
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Clement



Joined: 24 Apr 2006
Posts: 1110
Location: Dar es Salaam Tanzania

PostPosted: Fri Apr 08, 2022 4:10 pm    Post subject: Reply with quote

Mogulmeister wrote:
Very nice Clement. I like the way that your loop causes then pirouettes into the UR and back round again.
Thanks. The UR kept appearing but, took me time to realize that it was useful.
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dongrave



Joined: 06 Mar 2014
Posts: 563

PostPosted: Sat Apr 09, 2022 1:08 am    Post subject: Reply with quote

Clement wrote:
Mogulmeister wrote:
Very nice Clement. I like the way that your loop causes then pirouettes into the UR and back round again.
Thanks. The UR kept appearing but, took me time to realize that it was useful.

Clement! Thanks to you I learned the 6 different types of UR's today! Please keep on posting!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Tue Apr 12, 2022 10:00 am    Post subject: Reply with quote

I started looking at this with a contradictory hat on and observed that if you said that r6c1 = 3 then all manner of bad things happen. Using Don's grid (and lettering)

r2c1 = 9 r1c2 = 1 then a = 6 (r9c2) and b = 1 (r8c3) so c = 8 (r8c5) and d < > 6

at the same time

f = 8 (r6c2) and e = 1 (r6c6) and d also < > 1

So Arrow c = 8 and d = 8 and we now have two 8's in box 8 Arrow impossibility so r6c1 < > 3 and puzzle solved.
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Pat



Joined: 23 Feb 2010
Posts: 207

PostPosted: Thu Apr 14, 2022 5:22 am    Post subject: Reply with quote

Code:
+-------------+------------------+------------------+
| 5   19   6  | 4     2    189   | 7      189   3   |
| 39  37   8  | 5     167  1679  | 124    129   24  |
| 4   2    17 | 1389  178  13789 | 158    1589  6   |
+-------------+------------------+------------------+
| 6   5    9  | 18    3    2     | 148    178   478 |
| 1   378  27 | 6     5    4     | 238    238   9   |
| 23  38   4  | 7     9    18    | 12358  6     258 |
+-------------+------------------+------------------+
| 8   69   5  | 239   67   3679  | 23     4     1   |
| 29  4    12 | 1389  18   5     | 6      378   78  |
| 7   16   3  | 128   4    168   | 9      258   258 |
+-------------+------------------+------------------+

    yes, seems it needs split attention:

    if r8c1 = 2
    then
    r8c3 = 1

    then two things happen:
      • r8c5 = 8
      • r9c2 = 6

    combined → r9c6 = 1, r6c6 = 8, r6c2 = 3, r6c1 = 2, conflict in c1
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Sun Apr 17, 2022 11:42 am    Post subject: Reply with quote

Absolutely Pat - when you make r6c1 = 3 which makes r8c1 = 2 as you say, we need to recognise this bifurcation or split.

To put a nice bow on all this contradiction and sorry about the graphics*, I am going to have a go at this in Eureka:

Code:
2r8c1-(2=1)r8c3-(1=8)r8c5-(68=1)r9c6-(1=8)r6c6-(8=3)r6c2-(3=2)r6c1-(2)r8c1; r8c1 < > 2; stte   
            |               ^
            V               |
         (1=6)r9c2-----------


If you plug 2 into r8c1 the loop removes it showing that it can not be 2. A tributary forms at r8c3 and then rejoins the main river at r9c6.

*Diagram only works in full screen mode on a PC or Mac!
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