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Puzzle NR_046

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daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Jun 23, 2009 6:12 am Post subject: Puzzle NR_046

I'm going to post easier puzzles for awhile.

Code:

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

Play this puzzle online at the Daily Sudoku site

Code:

r3 b3 Locked Pair <> 59 [r3c1456]
r3 Naked Pair <> 13 [r3c14]

c5b1 turbot fish/ER <> 5 [r4c1]

XY-Wing [r2c1]/[r1c2]+[r4c1] <> 3 [r46c2]

Last edited by daj95376 on Sat Jul 04, 2009 4:14 pm; edited 1 time in total

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Tue Jun 23, 2009 9:56 pm Post subject:

Code:

.------------------------.------------------------.------------------------.
| 9 35 U136 | 3567 U135 567 | 2 4 8 |
|*56 8 4 |-56 9 2 | 3 7 1 |
| 7 2 U13 | 48 U13 48 | 59 6 59 |
:------------------------+------------------------+------------------------:
| 356 357 3689 | 356789 35 5678 | 4 1 2 |
| 256 1 2689 | 5689 4 568 | 569 3 7 |
| 4 357 369 | 35679 2 1 | 569 8 59 |
:------------------------+------------------------+------------------------:
| 23 4 23 | 1 8 9 | 7 5 6 |
| 1 9 7 | 45 6 45 | 8 2 3 |
| 8 6 5 | 2 7 3 | 1 9 4 |
'------------------------'------------------------'------------------------'

UR13[(5)r1c4 = (6)r1c3] - (6=5)r2c1; r2c4 <> 5

arkietech

Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

Posted: Tue Jun 23, 2009 11:27 pm Post subject:

storm_norm wrote:

Code:

UR13[(5)r1c4 = (6)r1c3] - (6=5)r2c1; r2c4 <> 5

I am struggling with Eureka notation.

The UR 13 will cause either r1c3 = 6 or r1c5 = 5
if r1c3=6 then r2c1=5
if r1c5=5 then r2c1=5 => r2c1=5

I am attempting to read and understand your Eureka statement. Is it the equivalent?

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Wed Jun 24, 2009 1:09 am Post subject:

arkietech wrote:

storm_norm wrote:

Code:

UR13[(5)r1c4 = (6)r1c3] - (6=5)r2c1; r2c4 <> 5

I am struggling with Eureka notation.

While you're waiting for Norm's explanation, let me interject.

Norm and I tend to use short chains where a lot is inferred by the chain endpoints. In this case, an Asellus extension would be more appropriate to help you understand what's happening.

Code:

(5)r2c4 - UR13[(5)r1c4 = (6)r1c3] - (6=5)r2c1 - (5)r2c4; r2c4 <> 5

In this case, assuming [r2c4]=5 forces one side of the UR constraint false ... and thus the other side true. This then leads to a contradiction on the assumption being true.

arkietech

Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

Posted: Wed Jun 24, 2009 3:08 am Post subject:

daj95376 said:

Quote:

(5)r2c4 - UR13[(5)r1c4 = (6)r1c3] - (6=5)r2c1 - (5)r2c4; r2c4 <> 5

In this case, assuming [r2c4]=5 forces one side of the UR constraint false ... and thus the other side true. This then leads to a contradiction on the assumption being true.

Thanks Danny -- that helps Very Happy

I was looking at a contridiction in row1 You are in row2

Marty R.

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

Posted: Sun Jun 28, 2009 3:25 am Post subject:

I used the URs on 59 and 13, followed by an XY-Wing on 153.

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