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Set XY_01 Puzzle 18

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Mon Mar 30, 2009 5:57 am    Post subject: Set XY_01 Puzzle 18 Reply with quote
Advanced, and my solver needed an XY-Chain.

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

Play this puzzle online at the Daily Sudoku site

Code:
     b2  Naked  Triple                   <> 467  [r1c46],[r2c456],[r3c5]
     b2  Naked  Triple                   <> 158  [r2c4]
 r3  b2  Locked Candidate 1              <> 4    [r3c1]
 r3      Naked  Pair                     <> 39   [r3c2]

         UR Type 1 [r23c15]              <> 39   [r2c1]   extraneous

         Empty Rectangle c5b1            <> 7    [r4c2]

 XY-Chain: a-b-c-d => [r2c2]<>5
 +-----------------------------------------------------------------------+
 |  2      567    678    |  18     67     158    |  9      3      4      |
 |  458    9-5    348    |  2      39    a58     |  6      7      1      |
 |  39     67     1      |  467    39     46     |  2      8      5      |
 |-----------------------+-----------------------+-----------------------|
 |  3458  d25     3478   |  9      247   b48     |  1     c24     6      |
 |  49     12679  467    |  1467   5      146    |  3      24     8      |
 |  48     126    468    |  1468   246    3      |  5      9      7      |
 |-----------------------+-----------------------+-----------------------|
 |  6      4      5      |  3      8      9      |  7      1      2      |
 |  1      3      2      |  46     46     7      |  8      5      9      |
 |  7      8      9      |  5      1      2      |  4      6      3      |
 +-----------------------------------------------------------------------+
 # 57 eliminations remain


Last edited by daj95376 on Sat Apr 11, 2009 12:53 am; edited 1 time in total
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storm_norm



Joined: 18 Oct 2007
Posts: 1741
PostPosted: Mon Mar 30, 2009 7:29 pm    Post subject: Reply with quote
Code:
.---------------------.---------------------.---------------------.
| 2      567    678   | 18     67     158   | 9      3      4     |
|3458-9 F59     348   | 2      39    E58    | 6      7      1     |
|3-9     67     1     | 467    39     46    | 2      8      5     |
:---------------------+---------------------+---------------------:
| 3458   257    3478  | 9      247   D48    | 1      24     6     |
|A49    1267-9  467   | 1467   5      146   | 3      24     8     |
|B48     126    468   |C1468   246    3     | 5      9      7     |
:---------------------+---------------------+---------------------:
| 6      4      5     | 3      8      9     | 7      1      2     |
| 1      3      2     | 46     46     7     | 8      5      9     |
| 7      8      9     | 5      1      2     | 4      6      3     |
'---------------------'---------------------'---------------------'

lets see what we learn from w-wings...

the 8's in box 5 are conjugate marked C and D
they see the {4,8} cell at B and the {5,8} cell at E
we have learned from w-wings that either the 4 at B is true
or the 5 at E is true, right?

now notice that both the 4 and the 5 see cells that also contain 9's Idea Idea
at A and F
A.K.A. extensions Cool (and not hair extensions)

so now either the 9 at A is true or the 9 at F is true. see?
eliminates 9's at r2c1, r3c1 and r5c2

(9=4)A - (4=8}B - (8}C = (8}D - (8=5)E - (5=9)F

that blasts a hole for a while

all that is left is a ER 7 and its done.
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Mon Mar 30, 2009 10:03 pm    Post subject: Reply with quote
Norm: I love how you and others start in the middle of a chain and work out. It's an approach that lends logic to a chain that would lack a personality otherwise. I also appreciate the fact that you labeled the cells so they played out sequentially when listed as a chain.

Now, if you had labeled cell [r4c8] as "C" and cell [r5c8] as "B", then you would have a boring XY-Chain!
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storm_norm



Joined: 18 Oct 2007
Posts: 1741
PostPosted: Mon Mar 30, 2009 10:13 pm    Post subject: Reply with quote
daj95376 wrote:
Norm: I love how you and others start in the middle of a chain and work out. It's an approach that lends logic to a chain that would lack a personality otherwise. I also appreciate the fact that you labeled the cells so they played out sequentially when listed as a chain.

Now, if you had labeled cell [r4c8] as "C" and cell [r5c8] as "B", then you would have a boring XY-Chain!

is that the xy-chain your solver found?
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Mon Mar 30, 2009 11:19 pm    Post subject: Reply with quote
storm_norm wrote:
daj95376 wrote:
Norm: I love how you and others start in the middle of a chain and work out. It's an approach that lends logic to a chain that would lack a personality otherwise. I also appreciate the fact that you labeled the cells so they played out sequentially when listed as a chain.

Now, if you had labeled cell [r4c8] as "C" and cell [r5c8] as "B", then you would have a boring XY-Chain!

is that the xy-chain your solver found?

Almost. My solver performed the Empty Rectangle elimination [r4c2]<>7 first. This exposed a 4-cell XY-Chain.

Code:
 *--------------------------------------------------------------------*
 | 2      567    678    | 18     67     158    | 9      3      4      |
 | 34589  9-5    348    | 2      39    a58     | 6      7      1      |
 | 39     67     1      | 467    39     46     | 2      8      5      |
 |----------------------+----------------------+----------------------|
 | 3458  d25     3478   | 9      247   b48     | 1     c24     6      |
 | 49     12679  467    | 1467   5      146    | 3      24     8      |
 | 48     126    468    | 1468   246    3      | 5      9      7      |
 |----------------------+----------------------+----------------------|
 | 6      4      5      | 3      8      9      | 7      1      2      |
 | 1      3      2      | 46     46     7      | 8      5      9      |
 | 7      8      9      | 5      1      2      | 4      6      3      |
*--------------------------------------------------------------------*

Note: My solver's XY-Chain lacks ... personality!
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Tue Apr 07, 2009 3:43 pm    Post subject: Reply with quote
Quote:
Advanced, and my solver needed an XY-Chain.

As is often the case, I missed any XY-Chain that might've been present. My solver (the one between the ears) needed the UR on 39, the ER on 7, and a Medusa wrap followed by the hidden UR on 48.
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