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oaxen
Joined: 10 Jul 2006
Posts: 96
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 Posted: Sun Jul 16, 2006 2:03 pm Post subject: July16 very hard |
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I gave up. After receiving the following pattern I had to ask for a hint. Gives me 5 in c3r5. I suppose because the program will eliminate the other possibility, 7, in the same cell, but why? Am I blind now again?
3798xx5x2
x2xxx7x38
816253479
xx2x1x84x
x8xxxxx2x
x3xx829xx
7x153928x
2534x8x9x
xx8x2x35x
Lars (oaxen) |
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Chuck B
Joined: 24 Jun 2006
Posts: 24
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| Posted: Sun Jul 16, 2006 3:24 pm Post subject: |
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| Code: | *--------------------------------------------------------------------*
| 3 7 9 | 8 46 146 | 5 16 2 |
| 45 2 45 | 169 469 7 | 16 3 8 |
| 8 1 6 | 2 5 3 | 4 7 9 |
|----------------------+----------------------+----------------------|
| 569 69 2 | 3679 1 56 | 8 4 3567 |
| 14569 8 >457< | 3679 4679*# 456# | 167* 2 13567 |
| 1456 3 457 | 67 8 2 | 9 16 1567 |
|----------------------+----------------------+----------------------|
| 7 46 1 | 5 3 9 | 2 8 46 |
| 2 5 3 | 4 67* 8 | 167* 9 167 |
| 469 469 8 | 167 2 16 | 3 5 1467 |
*--------------------------------------------------------------------* |
The candidates for R5C3 are 4, 5 and 7.
One of the cells R5C5 and R5C6 (marked with #, above) must hold block 5's '4', which eliminates 4 as a candidate for R5C3.
There is an X-wing in '7' at R58C57 (marked with '*', above), which eliminates '7' as a candidate from all other cells in rows 5 and 8 - in particular, for R5C3.
5 is the only candidate left in R5C3.
Cheers!
- cb |
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David
Joined: 02 Jun 2006
Posts: 58
Location: Bedford, UK
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| Posted: Sun Jul 16, 2006 4:01 pm Post subject: |
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| There is an X wing on 7's at r4c49 and r9c49. This allows reduction of cell at r6c4 to a 6, and the rest of the puzzle falls out. |
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TexCat
Joined: 07 Jul 2006
Posts: 32
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| Posted: Sun Jul 16, 2006 4:03 pm Post subject: |
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| Code: |
- - - | - - - | - - - |
- - - | - - - | - - - |
- - - | - - - | - - - |
- - - | 7* - - | - - 7 |
- - 7 | 7 7 - | 7* - 7 |
- - 7* | 7 - - | - - 7 |
- - - | - - - | - - - |
- - - | - 7* - | 7 - 7 |
- - - | 7 - - | - - 7* |
============================
- - - | - - - | - - - |
- - - | - - - | - - - |
- - - | - - - | - - - |
- - - | 7 - - | - - 7* |
- - 7 | 7 7* - | 7 - 7 |
- - 7* | 7 - - | - - 7 |
- - - | - - - | - - - |
- - - | - 7 - | 7* - 7 |
- - - | 7* - - | - - 7 | |
I gave up and used trial and error on the 7's in column 7. First I assumed that row 5 was 7, then that row 8 was a 7. In both cases, R6C3 had to be a 7. I filled the 7 in there and everything else was pie. I never can find the xy-wings, but if I suspect that's what is needed, sometimes trial and error on just 1 number will work for me. |
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TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
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| Posted: Sun Jul 16, 2006 5:26 pm Post subject: |
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Another way of looking at it:
| Code: |
*-----------*
|.79|...|5..|
|...|..7|..8|
|...|25.|4.9|
|---+---+---|
|..2|.1.|.4.|
|.8.|...|.2.|
|.3.|.8.|9..|
|---+---+---|
|7.1|.39|...|
|2..|4..|...|
|..8|...|35.|
*-----------*
*--------------------------------------------------------------------*
| 34 7 9 | 8 46 146 | 5 136 2 |
| 345 2 45 | 169 469 7 | 16 136 8 |
| 8 1 6 | 2 5 3 | 4 7 9 |
|----------------------+----------------------+----------------------|
| 569 69 2 |(37) 1 56 | 8 4 (37) |
| 156 8 57 | 3679 4679 456 | 167 2 13567 |
| 1456 3 (457) |(67) 8 2 | 9 16 (1567) |
|----------------------+----------------------+----------------------|
| 7 46 1 | 5 3 9 | 2 8 46 |
| 2 5 3 | 4 67 8 | 167 9 167 |
| 69 49 8 |(167) 2 16 | 3 5 (47) |
*--------------------------------------------------------------------*
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Marked cells form a swordfish (degenerate, I think, because one column contains only one cell) which makes the same key exclusion as the one x-wing (leaves r5c3 as a naked single). |
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oaxen
Joined: 10 Jul 2006
Posts: 96
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| Posted: Mon Jul 17, 2006 7:20 am Post subject: |
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| Thank you Chuck B. I missed your X-wing |
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