- Code: Select all
*-----------*
|..4|.29|..5|
|8..|...|.32|
|.3.|..4|1..|
|---+---+---|
|..5|...|..3|
|.2.|518|.7.|
|1..|...|5..|
|---+---+---|
|..8|4..|.5.|
|25.|...|..9|
|9..|65.|3..|
*-----------*
Play/Print this puzzle online
April 21, 2014
9 posts
• Page 1 of 1
April 21, 2014
by ArkieTech » Sun Apr 20, 2014 10:54 pm
Play/Print this puzzle online
dan
-
ArkieTech - Posts: 3355
- Joined: 29 May 2006
- Location: NW Arkansas USA
Re: April 21, 2014
by Leren » Mon Apr 21, 2014 12:49 am
- Code: Select all
*--------------------------------------------------------------*
| 67 1 4 | 3 2 9 |b678 6-8 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | 78 678 4 | 1 9 67 |
|--------------------+--------------------+--------------------|
| 467 89 5 | 29 47 67 | 289 1 3 |
| 346 2 369 | 5 1 8 | 69 7 46 |
| 1 6789 679 | 29 347 367 | 5 268 468 |
|--------------------+--------------------+--------------------|
| 367 67 8 | 4 9 1237 |b267 5 167 |
| 2 5 1367 | 78 378 137 |b67 4 9 |
| 9 4 17 | 6 5 127 | 3 a28 178 |
*--------------------------------------------------------------*
ALS XZ Rule: X = 2, Z = 8: (8=2) r9c8 - (2=8) r178c7 => - 8 r1c8; stte
Leren
- Leren
- Posts: 5039
- Joined: 03 June 2012
Re: April 21, 2014
by pjb » Mon Apr 21, 2014 1:41 am
- Code: Select all
67 1 4 | 3 2 9 |c678 d68 5
8 679 679 | 1 67 5 | 4 3 2
5 3 2 | 78 678 4 | 1 9 67
---------------------+----------------------+---------------------
467 89 5 | 29 47 67 |b289 1 3
346 2 369 | 5 1 8 | 69 7 46
1 6789 679 | 29 347 367 | 5 a28-6 468
---------------------+----------------------+---------------------
367 67 8 | 4 9 1237 | 267 5 167
2 5 1367 | 78 378 137 | 67 4 9
9 4 17 | 6 5 127 | 3 28 178
(2)r6c8 = (2-8)r4c7 = r1c7 - (8=6)r1c8 => -6 r6c8; stte
Phil
- pjb
- 2014 Supporter
- Posts: 2568
- Joined: 11 September 2011
- Location: Sydney, Australia
Re: April 21, 2014
by SteveG48 » Mon Apr 21, 2014 1:54 am
- Code: Select all
*-----------------------------------------------------------*
| 67 1 4 | 3 2 9 |a678 b68 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | 78 678 4 | 1 9 67 |
*-------------------+-------------------+-------------------|
| 467 89 5 | 29 47 67 | 29-8 1 3 |
| 346 2 369 | 5 1 8 | 69 7 c46 |
| 1 6789 679 | 29 347 367 | 5 c268 d468 |
*-------------------+-------------------+-------------------|
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | 78 378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 c28 178 |
*-----------------------------------------------------------*
(8)r1c7 = r1c8 - (8=246)r5c9,r69c8 - (46=8)r6c9 => -8 r4c7 ; stte
Steve
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SteveG48 - 2019 Supporter
- Posts: 4240
- Joined: 08 November 2013
- Location: Orlando, Florida
Re: April 21, 2014
by JC Van Hay » Mon Apr 21, 2014 5:55 am
- Code: Select all
+-----------------+---------------+--------------------+
| 67 1 4 | 3 2 9 | 67(8) 6(8) 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | 78 678 4 | 1 9 67 |
+-----------------+---------------+--------------------+
| 467 89 5 | 29 47 67 | 9-8(2) 1 3 |
| 346 2 369 | 5 1 8 | 69 7 46 |
| 1 6789 679 | 29 347 367 | 5 68(2) 468 |
+-----------------+---------------+--------------------+
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | 78 378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 (28) 178 |
+-----------------+---------------+--------------------+
- JC Van Hay
- Posts: 719
- Joined: 22 May 2010
Re: April 21, 2014
by Ngisa » Mon Apr 21, 2014 5:11 pm
- Code: Select all
+---------------+-------------+-------------+
| 7-6 1 4 | 3 2 9 | 678 a68 5 |
| 8 h679 h679 | 1 g67 5 | 4 3 2 |
| 5 3 2 | 78 f678 4 | 1 9 e67 |
+---------------+-------------+-------------+
| 467 89 5 | 29 47 67 | 289 1 3 |
| 346 2 369 | 5 1 8 | 69 7 d46 |
| 1 6789 679 | 29 347 367 | 5 268 d468 |
+---------------+-------------+-------------+
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | 78 378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 b28 c178 |
+---------------+-------------+-------------+
- Ngisa
- Posts: 1382
- Joined: 18 November 2012
Re: April 21, 2014
by daj95376 » Mon Apr 21, 2014 5:38 pm
_
You'll notice that a contradiction occurs when the contents of r3c9 is eliminated by the chain. When I wrote my first Sudoku solver, the possibility of a contradiction within a chain was difficult to accept. I think that's partially why that solver's chain logic ended up being (primarily) network logic. To this day, I occasionally stop and ponder how a hybrid chain-network logic might be structured ... and I'm not talking about incorporating ALS.
Note: the above chain can be turned into a lasso (discontinuous loop) by reversing the chain at the contradiction:
We can then drop the first and last SIs in the lasso segments ... and get a simpler discontinuous loop:
Why would you ever post a chain containing a lasso? I'm not sure. But, my solver is blocked from generating them because I never allow an SI to be reused -- forward or backward -- within a chain. That's why my initial chain above isn't a lasso.
_
- Code: Select all
+--------------------------------------------------------------+
| 67 1 4 | 3 2 9 | d678 68 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | b78 h678 4 | 1 9 cg67 |
|--------------------+--------------------+--------------------|
| 467 89 5 | 29 47 67 | e289 1 3 |
| 346 2 369 | 5 1 8 | 69 7 f46 |
| 1 6789 679 | 29 347 367 | 5 268 f468 |
|--------------------+--------------------+--------------------|
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | a78 i378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 28 178 |
+--------------------------------------------------------------+
# 66 eliminations remain
-from solver-
7r8c4 = r3c4 - r3c9 = (7-8)r1c7 = r4c7 - (8=46)r56c9 - 6r3c9 = (6-8)r3c5 = 8r8c5 => -7 r8c5; -8 r8c4
****** *******
You'll notice that a contradiction occurs when the contents of r3c9 is eliminated by the chain. When I wrote my first Sudoku solver, the possibility of a contradiction within a chain was difficult to accept. I think that's partially why that solver's chain logic ended up being (primarily) network logic. To this day, I occasionally stop and ponder how a hybrid chain-network logic might be structured ... and I'm not talking about incorporating ALS.
Note: the above chain can be turned into a lasso (discontinuous loop) by reversing the chain at the contradiction:
- Code: Select all
7r8c4 = r3c4 - r3c9 = (7-8)r1c7 = r4c7 - (8=46)r56c9 - (6=7)r3c9 - r3c4 = 7r8c4
******************* ######################
We can then drop the first and last SIs in the lasso segments ... and get a simpler discontinuous loop:
- Code: Select all
7r3c9 = (7-8)r1c7 = r4c7 - (8=46)r56c9 - (6=7)r3c9
Why would you ever post a chain containing a lasso? I'm not sure. But, my solver is blocked from generating them because I never allow an SI to be reused -- forward or backward -- within a chain. That's why my initial chain above isn't a lasso.
_
- daj95376
- 2014 Supporter
- Posts: 2624
- Joined: 15 May 2006
Re: April 21, 2014
by Marty R. » Mon Apr 21, 2014 6:21 pm
- Code: Select all
+---------------+-------------+-------------+
| 67 1 4 | 3 2 9 | 678 68 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | 78 678 4 | 1 9 67 |
+---------------+-------------+-------------+
| 467 89 5 | 29 47 67 | 289 1 3 |
| 346 2 369 | 5 1 8 | 69 7 46 |
| 1 6789 679 | 29 347 367 | 5 268 468 |
+---------------+-------------+-------------+
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | 78 378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 28 178 |
+---------------+-------------+-------------+
Play this puzzle online at the Daily Sudoku site
Same as Leren's result: (8=2)r9c8-(267=8)r781c7=>r1c8<>8
Leren: Why did you assign values to X and Z?
ALS XZ Rule: X = 2, Z = 8: (8=2) r9c8 - (2=8) r178c7 => - 8 r1c8; stte
The chain obviously works without the preface.
- Marty R.
- Posts: 1508
- Joined: 23 October 2012
- Location: Rochester, New York, USA
Re: April 21, 2014
by Luke » Mon Apr 21, 2014 7:13 pm
Variation on a theme and another almost wing solution.
(9)r4c7=[w-wing (28)r4c7,r9c8 + SL(8)c9]-(2)r6c8=(2)r4c7 ==>r4c7<>8
- Code: Select all
*-----------------------------------------------------------*
| 67 1 4 | 3 2 9 | 678 68 5 |
| 8 679 679 | 1 67 5 | 4 3 2 |
| 5 3 2 | 78 678 4 | 1 9 67 |
|-------------------+-------------------+-------------------|
| 467 89 5 | 29 47 67 |*28+9 1 3 |
| 346 2 369 | 5 1 8 | 69 7 46 |
| 1 6789 679 | 29 347 367 | 5 268 S468 |
|-------------------+-------------------+-------------------|
| 367 67 8 | 4 9 1237 | 267 5 167 |
| 2 5 1367 | 78 378 137 | 67 4 9 |
| 9 4 17 | 6 5 127 | 3 *28 S178 |
*-----------------------------------------------------------*
(9)r4c7=[w-wing (28)r4c7,r9c8 + SL(8)c9]-(2)r6c8=(2)r4c7 ==>r4c7<>8
-
Luke - 2015 Supporter
- Posts: 435
- Joined: 06 August 2006
- Location: Southern Northern California
9 posts
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