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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Sep 22, 2007 1:17 pm Post subject: DB Saturday Puzzle: September 22, 2007 |
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| Code: | Puzzle: DB092207 ******
+-------+-------+-------+
| 7 . . | 1 . . | 6 . . |
| . . . | . . 6 | . 1 4 |
| 1 . . | . 5 . | . . 2 |
+-------+-------+-------+
| . 3 . | 4 . . | 8 2 . |
| . . . | 7 . 2 | . . . |
| . 7 1 | . . 9 | . 3 . |
+-------+-------+-------+
| 8 . . | . 2 . | . . 3 |
| 3 1 . | 8 . . | . . . |
| . . 7 | . . 5 | . . 8 |
+-------+-------+-------+ |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 22, 2007 3:27 pm Post subject: Satruday DB Sept 22 |
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I am stuck at this point.
Earl
| Code: |
+---------------+--------+----------+
| 7 25 235 | 1 4 38 | 6 58 9 |
| 59 589 3589 | 2 7 6 | 35 1 4 |
| 1 46 46 | 9 5 38 | 37 78 2 |
+---------------+--------+----------+
| 59 3 59 | 4 6 1 | 8 2 7 |
| 46 468 468 | 7 3 2 | 59 59 1 |
| 2 7 1 | 5 8 9 | 4 3 6 |
+---------------+--------+----------+
| 8 459 459 | 6 2 47 | 1 479 3 |
| 3 1 246 | 8 9 47 | 27 467 5 |
| 469 2469 7 | 3 1 5 | 29 469 8 |
+---------------+--------+----------+
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Play this puzzle online at the Daily Sudoku site |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 22, 2007 3:29 pm Post subject: |
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| There was a Type 1 on 59 and Type 3 on 47. The implications of the latter forced a couple of cells and that finished the puzzle. I strongly suspect there are other solutions that I missed. |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Sat Sep 22, 2007 3:48 pm Post subject: Saturday DB sept 22 |
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Marty,
Could you show the details of how you applied the type 3 UR of 47's.
I cant see how the <69> makes a useful virtual cell.
Thanks.
Earl |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Sep 22, 2007 4:08 pm Post subject: Re: Saturday DB sept 22 |
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| Earl wrote: | Marty,
Could you show the details of how you applied the type 3 UR of 47's.
I cant see how the <69> makes a useful virtual cell.
Thanks.
Earl |
Earl, first of all, I don't know if I was working with the same grid that you are. To kill the "deadly pattern", either r7c8 must be 9 or r8c8 must be 6. Under either scenario two cells on box 7 were solved the same way. Or to put it another way, the rectangle steered me to a forcing chain. For me, this technique is somewhere between satisfying and non-satisfying. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Sep 22, 2007 5:10 pm Post subject: |
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I get to this point:
| Code: | +----------------+----------------+----------------+
| 7 25 235 | 1 4 38 | 6 58 9 |
| 59 589 3589 | 2 7 6 | 35 1 4 |
| 1 46 46 | 9 5 38 | 37 78 2 |
+----------------+----------------+----------------+
| 59 3 59 | 4 6 1 | 8 2 7 |
| 46 468 468 | 7 3 2 | 59 59 1 |
| 2 7 1 | 5 8 9 | 4 3 6 |
+----------------+----------------+----------------+
| 8 459 459 | 6 2 47 | 1 479a 3 |
| 3 1 246 | 8 9 47d | 27c 467e 5 |
| 46 2469 7 | 3 1 5 | 29b 469 8 |
+----------------+----------------+----------------+
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The UR takes <59> out of R2C3.
The other UR is on <47> in R78C68.
Thus R7C8 is is <9> and/or R8C8 is <6>.
If a is <9> then the chain abcde leads to R8C8 is <6>. So, R8C8 must be <6>. That still does not solve the puzzle.
Keith |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Sat Sep 22, 2007 7:55 pm Post subject: |
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| From Keith's grid there is a 7-cell xy-chain, that collapses the whole puzzle |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Sep 22, 2007 8:25 pm Post subject: |
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There are 6-cell chains for many of the cells.
There is a W-wing which takes out <4> in R5C2. Still not solved.
Keith |
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Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
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| Posted: Sat Sep 22, 2007 9:15 pm Post subject: |
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The 7-cell xy-chain using the two pincer cells for digit <2> in R1C2 and R9C7, which eliminates <2> in R9C2.
| Code: |
+--------------+--------+----------+
| 7 A25 235 | 1 4 38 | 6 B58 9 |
| 59 589 3589 | 2 7 6 |E35 1 4 |
| 1 46 46 | 9 5 38 |D37 C78 2 |
+--------------+--------+----------+
| 59 3 59 | 4 6 1 | 8 2 7 |
| 46 468 468 | 7 3 2 |F59 59 1 |
| 2 7 1 | 5 8 9 | 4 3 6 |
+--------------+--------+----------+
| 8 459 459 | 6 2 47 | 1 479 3 |
| 3 1 246 | 8 9 47 | 27 467 5 |
| 46-2469 7 | 3 1 5 |G29 469 8 |
+--------------+--------+----------+
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Sun Sep 23, 2007 3:45 am Post subject: |
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I'm late to this puzzle today. However, when I see a grid with so many bivalue cells with so many mixed digits that can all see each other, I think: Medusa!
And, I wasn't disappointed:
| Code: | +----------------+----------+-------------+
| 7 25 #2g3g5 | 1 4 3r8g | 6 5g8r 9 |
| 59 589 3589 | 2 7 6 | 35 1 4 |
| 1 46 46 | 9 5 38 | 37 78 2 |
+----------------+----------+-------------+
| 59 3 59 | 4 6 1 | 8 2 7 |
| 46 468 468 | 7 3 2 | 5g9r 5r9g 1 |
| 2 7 1 | 5 8 9 | 4 3 6 |
+----------------+----------+-------------+
| 8 459 459 | 6 2 47 | 1 479 3 |
| 3 1 2r46 | 8 9 47 | 27 467 5 |
| 46 2g469 7 | 3 1 5 | 2r9g 469 8 |
+----------------+----------+-------------+ |
With hardly any coloring at all, one finds two "greens" in R1C3 (marked #). This is not possible ("Medusa Wrap"), so all the "greens" can be eliminated and all "reds" placed and the puzzle totally collapses. Piece o' cake! |
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