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DB Saturday Puzzle: July 7, 2007

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keith

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

Posted: Sat Jul 07, 2007 2:40 pm Post subject: DB Saturday Puzzle: July 7, 2007

I have not yet completed this one ...

Code:

Puzzle: DB070707 ******
+-------+-------+-------+
| . 8 . | . . . | 6 . 5 |
| 1 . 6 | . . . | . 8 2 |
| . . 3 | . . . | 4 . . |
+-------+-------+-------+
| 8 . . | . . 6 | . . . |
| . . 9 | 8 5 4 | 3 . . |
| . . . | 9 . . | . . 7 |
+-------+-------+-------+
| . . 8 | . . . | 9 . . |
| 3 2 . | . . . | 5 . 4 |
| 9 . 5 | . . . | . 7 . |
+-------+-------+-------+

Keith

Earl

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

Posted: Sat Jul 07, 2007 4:34 pm Post subject: DB July 7

I got this far using basic techniques.

The next step eludes me.

Earl

Code:

+-----------+---------------+---------+
| 4 8 27 | 127 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 27 5 3 | 6 278 278 | 4 9 1 |
+-----------+---------------+---------+
| 8 3 4 | 127 127 6 | 12 5 9 |
| 27 17 9 | 8 5 4 | 3 12 6 |
| 5 6 12 | 9 123 123 | 8 4 7 |
+-----------+---------------+---------+
| 6 147 8 | 45 1247 1257 | 9 12 3 |
| 3 2 17 | 17 89 89 | 5 6 4 |
| 9 14 5 | 34 6 123 | 12 7 8 |
+-----------+---------------+---------+

Play this puzzle online at the Daily Sudoku site

ravel

Joined: 21 Apr 2006
Posts: 536

Posted: Sat Jul 07, 2007 4:37 pm Post subject:

SS is stuck here:

Code:

*--------------------------------------------------------------------*
| 4 8 27 | 127 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 257 57 3 | 267 2678 278 | 4 9 1 |
|----------------------+----------------------+----------------------|
| 8 35 124 | 237 1237 6 | 12 45 9 |
|@27 #17 9 | 8 5 4 | 3 @12 6 |
| 56 356 124 | 9 123 123 | 8 45 7 |
|----------------------+----------------------+----------------------|
| 6-7 #1467 8 | 24567 2467 257 | 9 12 3 |
| 3 2 @17 | 17 89 89 | 5 6 4 |
| 9 46 5 | 12346 12346 123 | 12 7 8 |
*--------------------------------------------------------------------*

There is no W-Wing for the 17's, but with the strong link for 1 in column 2 there is a similar deduction:
Either r5c2=1 => r5c1=7
or r7c2=1 => r8c3=7
So r6c1<>7.

Earl: There are 2 strong links (Kite) to remove 1 from r9c2 in your grid.

Asellus

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

Posted: Sat Jul 07, 2007 11:19 pm Post subject:

I didn't see Ravel's "Kite" (or coloring on <1>), but I still was able to make the <7> elimination using a slightly novel coloring:

Code:

+-------------------+
| 4 8 27 |
| 1 9 6 |
| 257 57 3 |
+-------------------+
| 8 35 (1r)24 |
| 27g 1g7r 9 |
| 56 356 (1r)24 |
+-------------------+
| 6-7 (1r)467 8 |
| 3 2 1g7r |
| 9 (1r)46 5 |
+-------------------+

Notice that there is a strong link on <1> between C2 and C3 in Boxes 4 and 7. I've used parentheses to denote this in the coloring, with red(r) and green(g). The <7> at R7C1 can see both colors of <7>.

Employing the Kite elimination plus a number of other steps, I was able to solve the puzzle. It reminded me of Ravel's posting of yesterday: a tough nut to crack that didn't submit easily.

ravel

Joined: 21 Apr 2006
Posts: 536

Posted: Sun Jul 08, 2007 7:57 pm Post subject:

Asellus wrote:

I didn't see Ravel's "Kite" (or coloring on <1>)

Code:

+------------+---------------+---------+
| 4 8 27 | 127 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 27 5 3 | 6 278 278 | 4 9 1 |
+------------+---------------+---------+
| 8 3 4 | 127 127 6 | 12 5 9 |
| 27 A17 9 | 8 5 4 | 3 B12 6 |
| 5 6 12 | 9 123 123 | 8 4 7 |
+------------+---------------+---------+
| 6 147 8 | 45 1247 1257 | 9 A12 3 |
| 3 2 17 | 17 89 89 | 5 6 4 |
| 9 -14 5 | 34 6 123 |B12 7 8 |
+------------+---------------+---------+

jLo

Joined: 30 Apr 2007
Posts: 55

Posted: Mon Jul 09, 2007 12:21 am Post subject:

Quote:

I got this far using basic techniques.

The next step eludes me.

There is a skyscraper on <2>s which solves R6C3 and pretty much wraps things up.

TexCat

Joined: 07 Jul 2006
Posts: 32

Posted: Mon Jul 09, 2007 3:09 am Post subject:

I got stuck way back at:

Code:

+----------------+-------------------+----------+
| 247 8 247 | 127 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 257 57 3 | 267 2678 278 | 4 9 1 |
+----------------+-------------------+----------+
| 8 1345 124 | 1237 1237 6 | 12 45 9 |
| 27 17 9 | 8 5 4 | 3 12 6 |
| 2456 13456 124 | 9 123 123 | 8 45 7 |
+----------------+-------------------+----------+
| 467 1467 8 | 124567 12467 1257 | 9 126 3 |
| 3 2 17 | 167 89 89 | 5 16 4 |
| 9 146 5 | 12346 12346 123 | 12 7 8 |
+----------------+-------------------+----------+

Play this puzzle online at the Daily Sudoku site

What am I missing here?

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Mon Jul 09, 2007 4:37 am Post subject:

Quote:

What am I missing here?

Same thing that I'm missing, because I'm stuck in the same place except I only have 24 in r1c1.

ravel

Joined: 21 Apr 2006
Posts: 536

Posted: Mon Jul 09, 2007 7:29 am Post subject:

Code:

Hard to spot: There is a hidden triple 356 (or naked quad 1247) in box 4.
I really recommend to use a program, after one has tried hard and is still stuck. How often did i miss basic moves !

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Mon Jul 09, 2007 3:52 pm Post subject:

Quote:

Hard to spot: There is a hidden triple 356 (or naked quad 1247) in box 4.

I'll take the quad over the hidden triple. Thanks, there's no excuse for missing that.

TKiel

Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI

Posted: Mon Jul 09, 2007 11:15 pm Post subject:

jLo wrote:

There is a skyscraper on <2>s which solves R6C3...

in regards to Earl's post.

I don't see this, but I do see the following multi-coloring option.

Code:

*-----------------------------------------------------------*
| 4 8 27A | 127B 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 27a 5 3 | 6 278 278 | 4 9 1 |
|-------------------+-------------------+-------------------|
| 8 3 4 | 127b 127 6 | 12A 5 9 |
| 27A 17 9 | 8 5 4 | 3 12a 6 |
| 5 6 12 | 9 123 123 | 8 4 7 |
|-------------------+-------------------+-------------------|
| 6 147 8 | 45 1247 1257 | 9 12 3 |
| 3 2 17 | 17 89 89 | 5 6 4 |
| 9 14 5 | 34 6 123 | 12 7 8 |
*-----------------------------------------------------------*

Both ends of the [B,b] chain see an A cell from the other chain, indicating that none of the cells marked with an A can be true.

jLo

Joined: 30 Apr 2007
Posts: 55

Posted: Fri Jul 13, 2007 12:49 am Post subject:

TKiel wrote:

jLo wrote:

There is a skyscraper on <2>s which solves R6C3...

in regards to Earl's post.

I don't see this, but I do see the following multi-coloring option.

Code:

+-----------+---------------+---------+
| 4 8 x27 |x127 1279 1279 | 6 3 5 |
| 1 9 6 | 345 34 35 | 7 8 2 |
| 27 5 3 | 6 278 278 | 4 9 1 |
+-----------+---------------+---------+
| 8 3 4 |x127 127 6 | 12 5 9 |
| 27 17 9 | 8 5 4 | 3 12 6 |
| 5 6 x12 | 9 X123 X123 | 8 4 7 |

+-----------+---------------+---------+
| 6 147 8 | 45 1247 1257 | 9 12 3 |
| 3 2 17 | 17 89 89 | 5 6 4 |
| 9 14 5 | 34 6 123 | 12 7 8 |
+-----------+---------------+---------+

Either one or both of R6C3 and R4C4 are <2>. Thus, <2> can be eliminated
from their common buddies - R6C5 and R6C6. This leaves a naked pair <13>
on Row 6, eliminating the 2 from R6C3.

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