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Interesting

 
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Earl



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

PostPosted: Mon Nov 26, 2007 5:37 pm    Post subject: Interesting Reply with quote

If today's VH went by took quickly, here is one that uses many techniques. Interesting.

Earl


Code:
*--------------------------------------------------------------------*
 | 4      18     57     | 1678   2      1689   | 3      58     5678   |
 | 1578   6      9      | 1378   1378   18     | 1478   2      4578   |
 | 1278   138    237    | 5      13678  4      | 1678   9      678    |
 |----------------------+----------------------+----------------------|
 | 78     5      47     | 9      1478   18     | 2      6      348    |
 | 3      48     2467   | 2678   45678  2568   | 489    458    1      |
 | 268    9      1      | 268    4568   3      | 48     7      458    |
 |----------------------+----------------------+----------------------|
 | 1569   2      356    | 4      13568  7      | 689    38     3689   |
 | 69     7      346    | 2368   368    268    | 5      1      34689  |
 | 156    134    8      | 136    9      156    | 467    34     2      |
 *--------------------------------------------------------------------*


(Edited by Marty to align grid)
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Earl



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

PostPosted: Mon Nov 26, 2007 5:46 pm    Post subject: Interesting Reply with quote

Here is the original grid.
I often cannot get the grids to line up correclty.

Earl

Code:

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

Play this puzzle online at the Daily Sudoku site
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Mon Nov 26, 2007 9:06 pm    Post subject: Reply with quote

hi earl,

nice puzzle, first real move is the x-wing on the 4 removes 4 from r5c5, then a number of ways you can from here. either an xy-chain or if you look at the 5's in rows 2, 6 and 7 and columns 1, 5 and 9, there is a finned sword fish, of course it doesn't do much, just takes out the 5 in r9c1. finding a sword fish is pretty interesting to me.

after that a finned x-wing on the 6's in rows 5 and 8 and columns 3 and 6 takes out 6 in r8c1.

the 6's look promising after that. but I think a couple more chains will have to do the trick.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

PostPosted: Mon Nov 26, 2007 9:59 pm    Post subject: Reply with quote

After the X-wing on <4>, coloring on <4> solves R6C7 as <8>. After that, a couple of XY-wings finish it off.

Keith
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Asellus



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

PostPosted: Thu Nov 29, 2007 10:19 pm    Post subject: Reply with quote

Keith,

How did you color <4>? I'm not seeing it.
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Asellus



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

PostPosted: Thu Nov 29, 2007 10:22 pm    Post subject: Reply with quote

There's an alternative to that Finned Swordfish. The <5> at R7C5 can see both ends of the strong link in C3 via ERs in Boxes 3, 6 and 5:
Code:
+---------------+-------------------+---------------+
| 4    18  A57  | 1678  2       9   | 3    58  5678 |
| 1578 6    9   | 1378  1378    18  |e148 e2   4578 |
| 1278 138  237 | 5     1678    4   |e168 e9   678  |
+---------------+-------------------+---------------+
| 78   5    47  |e9     148    e18  |e2   e6   3    |
| 3    48   26  | 2678  5678    256 | 9    458 1    |
| 26   9    1   |e268   4568   e3   |e48  e7   458  |
+---------------+-------------------+---------------+
| 1569 2   a356 | 4    #13-568  7   | 68   38  689  |
| 69   7    346 | 2368  368     26  | 5    1   4689 |
| 156  134  8   | 136   9       56  | 7    34  2    |
+---------------+-------------------+---------------+
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Asellus



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

PostPosted: Fri Nov 30, 2007 12:29 am    Post subject: Reply with quote

storm_norm's <6> elimination in R8C1 can also be seen as due to a {26} W-Wing (or Remote Pair) in R6C1 and R8C6. Then, more can be done with the <6>s...

There is a Finned X-Wing in C36 where the fin is visible to R8C4 via ERs in Boxes 9, 3 and 2 eliminating <6> in R8C4. However, this step isn't necessary.

Instead, there is a Color Wing (Multi-Coloring) that employs grouped coloring on the end of one chain:
Code:
+------------------+-----------------+---------------+
| 4     18   57    | 1678   2     9  | 3    58  5678 |
| 1578  6    9     | 1378   1378  18 | 148  2   4578 |
| 1278  138  237   | 5      1678  4  | 168  9   678  |
+------------------+-----------------+---------------+
| 78    5    47    | 9      148   18 | 2    6   3    |
| 3     48   26r   | 78     578   26g| 9    458 1    |
| 26    9    1     | 268    4568  3  | 48   7   458  |
+------------------+-----------------+---------------+
|#15-6  2    356(g)| 4      1368  7  | 68   38  9    |
| 9     7    346(g)| 2368   368   26r| 5    1   468  |
| 16R   134  8     | 136G   9     5  | 7    34  2    |
+------------------+-----------------+---------------+

The r-G "Bridge" is in Box 8. Eliminations occur between R and g. The grouped coloring is shown in parentheses in Box 7 C3. <6> is removed from R7C1.

The resulting strong link in C1 completes a color loop back to Box 8 eliminating <6> from R7C5 and R8C45. (This is why that Finned X-Wing with the ERs isn't necessary.)

Then, there is another Color Wing:
Code:
+---------------+---------------+---------------+
| 4    18   57  |G1678 2     9  | 3   58  R5678 |
| 1578 6    9   | 1378 1378  18 | 148 2    4578 |
| 1278 138  237 | 5    1678  4  | 168 9    678  |
+---------------+---------------+---------------+
| 78   5    47  | 9    148   18 | 2   6    3    |
| 3    48  g26  | 78   578  r26 | 9   458  1    |
|r26   9    1   | 268  4568  3  | 48  7    458  |
+---------------+---------------+---------------+
| 15   2    356 | 4    138   7  | 68  38   9    |
| 9    7    346 | 238  38   g26 | 5   1   #4-68 |
|g16   134  8   |r136  9     5  | 7   34   2    |
+---------------+---------------+---------------+

The r-G "Bridge" is in C4. <6> is removed from R8C9.

After this, two XY Wings complete the puzzle. The first pivots at R8C9 and eliminates a <3>. The second pivots at R7C8 and eliminates <5>.
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tlanglet



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

PostPosted: Fri Nov 30, 2007 12:36 am    Post subject: Reply with quote

Hi,

I am new at Sudoku and to this site, but how been following the discussions for awhile to learn.

After the basics, I found a finned x-wing to eliminate <2> at r5c3, then another finned x-wing to eliminate <1> at r3c2 & r2c4. Then a xyz_wing with pivot atr3c1 eliminated the <8> at r2c1. Finally a xy-wing with pivot at r9c2 eliminated <3> from r8c45 which solved the puzzle.

I have no idea if all these moves were required or even if all were truly correct but they worked.

Ted
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Asellus



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

PostPosted: Fri Nov 30, 2007 2:25 am    Post subject: Reply with quote

Hi Ted,

Welcome again! (I just replied to one of your posts on another thread.)

I believe you were lucky in this case. Here's the grid after basics:
Code:
+--------------+-----------------+--------------+
| 4    18  57  | 1678 2      9   | 3   58  5678 |
| 1578 6   9   | 1378 1378   18  | 148 2   4578 |
| 1278 138 237 | 5    1678   4   | 168 9   678  |
+--------------+-----------------+--------------+
| 78   5   47  | 9    148    18  | 2   6   3    |
| 3    48  26  |x2678 45678 x256 | 9   458 1    |
| 26   9   1   |f268  4568   3   | 48  7   458  |
+--------------+-----------------+--------------+
| 1569 2   356 | 4    13568  7   | 68  38  689  |
| 69   7   346 |x2368 368   x26  | 5   1   4689 |
| 156  134 8   | 136  9      56  | 7   34  2    |
+--------------+-----------------+--------------+

I have marked what you are probably considering to be your Finned X-Wing. Any "victim" cells must be able to "see" both the potential X-Wing and the Fin. The only such cell here is R5C5, which contains no <2>. The <2> in R5C3 can see the potential X-Wing but cannot see the Fin; so, it cannot be removed in this way.

A finned fish (such as Finned X-Wing) alone can only eliminate candidates within cells belonging to a single Box, the Box shared with the fin. Your <1> eliminations in R3C2 and R2C4 are in two different Boxes. So, that's not possible with a Finned X-Wing.

Don't get discouraged. These are "learning opportunities"!
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