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Free Press March 2, 2012

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keith

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

Posted: Sat Mar 03, 2012 12:50 pm Post subject: Free Press March 2, 2012

Not yet started ...

Code:

Puzzle: FP030212
+-------+-------+-------+
| . 7 . | . . . | . 2 5 |
| . . . | . 9 . | 4 . . |
| . . . | 8 . . | . 1 6 |
+-------+-------+-------+
| . 3 9 | . 2 . | 8 . . |
| . . . | 3 . 5 | . . . |
| . . 5 | . 1 . | 3 7 . |
+-------+-------+-------+
| 5 9 . | . . 3 | . . . |
| . . 2 | 1 8 . | . . . |
| 4 8 . | . . . | . 9 . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Sat Mar 03, 2012 2:13 pm Post subject:

Code:

+-------------------+------------------+---------------+
| 38(1) 7 348 | 46 346 6(14) | 9 2 5 |
| (12) 125 6 | 257 9 127 | 4 38 38 |
| 9 45(2) 34 | 8 345 (24) | 7 1 6 |
+-------------------+------------------+---------------+
| 7-1 3 9 | 467 2 67(4) | 8 5 (14) |
| 1278 124 478 | 3 47 5 | 126 46 9 |
| 6 24 5 | 9 1 8 | 3 7 24 |
+-------------------+------------------+---------------+
| 5 9 17 | 2467 467 3 | 126 68 1278 |
| 37 6 2 | 1 8 9 | 5 34 347 |
| 4 8 137 | 2567 567 267 | 126 9 1237 |
+-------------------+------------------+---------------+

5-SIS Kraken Column 4C6 => -1r4c1; stte

(4-1)r1c6=1r1c1
||
(4-2)r3c6=2r3c2-(2=1)r2c1
||
4r4c6-(4=1)r4c9

=> 1r12c1=1r4c9 => -1r4c1; stte

arkietech

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

Posted: Sat Mar 03, 2012 3:10 pm Post subject:

JC Van Hay wrote:

5-SIS Kraken Column 4C6 => -1r4c1; stte

(4-1)r1c6=1r1c1
||
(4-2)r3c6=2r3c2-(2=1)r2c1
||
4r4c6-(4=1)r4c9

=> 1r12c1=1r4c9 => -1r4c1; stte

WOW! beats my 3 steps.

How do you find these moves? Confused

Could this be a k-wing? Smile

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Sat Mar 03, 2012 4:08 pm Post subject:

Hi, Dan,

arkietech wrote:

WOW! beats my 3 steps.

I looked for a solution involving only Wings only after having found the kraken Very Happy

Here it is :

arkietech wrote:

How do you find these moves?

I don't look for them. As I don't waste time any more looking for patterns.
However, knowing them and in a word, I almost always stumble upon them.

What I am just doing to get a feeling of a puzzle is to apply StrataGEM after basics.

In this case, I first applied GEM to column 8 and then to B6 after solving C8.
I noticed that the colour on 4r4c9 implied the same colour for 1r1c6 and 4r1c6.
After that, I got stte.
I checked that this observation was independent of the first step.
This helped me to be focused on a simple justification of -4r4c9.
The result is the Kraken.

arkietech wrote:

Could this be a k-wing?

Would you mind being a bit more explicit on your meaning of "k-wing" ?

Best regards, JC.

Luke451

Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

Posted: Sat Mar 03, 2012 5:16 pm Post subject:

JC Van Hay wrote:

What I am just doing to get a feeling of a puzzle is to apply StrataGEM after basics.

"StrataGEM"? I'd be interested to learn more about this. A search did not turn up anything. Is it a program, a process, or just a, well, stratagem?

Thanks.

Marty R.

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

Posted: Sat Mar 03, 2012 6:43 pm Post subject:

I used three steps too. XY-Chain; r8c8<>3 DP 46, using pincers; r1c1<>1 W-Wing (12), SL 2 in c2; r5c1<>2

arkietech

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

Posted: Sat Mar 03, 2012 6:47 pm Post subject:

JC Van Hay wrote:

Would you mind being a bit more explicit on your meaning of "k-wing" ?

Kraken wing Very Happy

it was just a joke.

Thanks for the tips!

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Sat Mar 03, 2012 7:56 pm Post subject:

Luke451 wrote:

JC Van Hay wrote:

What I am just doing to get a feeling of a puzzle is to apply StrataGEM after basics.

"StrataGEM"? I'd be interested to learn more about this. A search did not turn up anything. Is it a program, a process, or just a, well, stratagem?

Thanks.

StrataGEM and GEMini are terms coined by Dpbobelisk in the thread on Aran's Red Green Transport here.

I am maybe misusing David's idea. But, by "hijacking" the term StrataGEM, I mean a combination of David's Graded Equivalence Marks and Aran's Red Green Transport from multiple starting points.
It being understood that the usefull starting points result from a carefull analysis of the B/B-Plot (as defined by SteveK in his blog on the au site, for example) and from the knowledge obtained after an exhaustive simple "colouring" (to use SteveK vocabulary, again) on each digit.

Best regards, JC.

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Sat Mar 03, 2012 8:00 pm Post subject:

arkietech wrote:

Kraken wing Very Happy

it was just a joke.

I understood that you were "joking, Mr Feynman" Very Happy

Best regards, JC.

Orkamat

Joined: 20 Dec 2011
Posts: 10
Location: Winnipeg, Canada

Posted: Sat Mar 03, 2012 9:10 pm Post subject:

JC Van Hay wrote:

StrataGEM and GEMini are terms coined by Dpbobelisk in the thread on Aran's Red Green Transport here.

Wow! Some folks there take their sudoku, IMO, a little too seriously and personally. They could use a hobby. Very Happy

I understand now the objection raised elsewhere to "assumptive" strategies, and why personal opinions and boundaries (= what is and is not assumptive) vary so widely. To me, any strategy that uses coloring, chains, etc. smacks of T&E, but that's changing as my comfort level with more difficult puzzles and strategies grows.

Personally, I rely heavily on abductive logic; I've got a near-perfect record at solving puzzles by misapplying methods. As my g'ma used to tell me: if you can't be good, be lucky.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sat Mar 03, 2012 11:31 pm Post subject:

Hmmm!!! Not what I'd expect from a newspaper puzzle.

It can be done in one (interesting?) complex step:

Code:

after basics
+--------------------------------------------------------------+
| 138 7 348 | d46 d346 c146 | 9 2 5 |
| 12 f125 6 | 257 9 127 | 4 38 38 |
| 9 e245 34 | 8 d345 c24 | 7 1 6 |
|--------------------+--------------------+--------------------|
| 7-1 3 9 | 467 2 b467 | 8 5 a14 |
| 1278 g124 478 | 3 47 5 | 26-1 46 9 |
| 6 24 5 | 9 1 8 | 3 7 24 |
|--------------------+--------------------+--------------------|
| 5 9 17 | 2467 467 3 | 126 68 1278 |
| 37 6 2 | 1 8 9 | 5 34 347 |
| 4 8 137 | 2567 567 267 | 126 9 1237 |
+--------------------------------------------------------------+
# 73 eliminations remain

(1=4)r4c9 - r4c6 = r13c6 - (346=5)r1c45,r3c5 - r3c2 = (5-1)r2c2 = (1)r5c2
=> r4c1,r5c7<>1

Or in three steps using two chains/wings:

Code:

after basics
+--------------------------------------------------------------+
| 138 7 348 | 46 346 146 | 9 2 5 |
| 12 125 6 | 257 9 127 | 4 38 38 |
| 9 245 34 | 8 345 24 | 7 1 6 |
|--------------------+--------------------+--------------------|
| c17 3 9 | b467 2 b467 | 8 5 14 |
| 1278 124 478 | 3 a47 5 | 126 6-4 9 |
| 6 24 5 | 9 1 8 | 3 7 24 |
|--------------------+--------------------+--------------------|
| 5 9 17 | 2467 467 3 | 126 68 1278 |
| d37 6 2 | 1 8 9 | 5 f34 e347 |
| 4 8 137 | 2567 567 267 | 126 9 1237 |
+--------------------------------------------------------------+
# 73 eliminations remain

M4-Wing: (4=7)r5c5 - r4c46 = r4c1 - r8c1 = (7-4)r8c9 = (4)r8c8 => r5c8<>4

+---------------------------------------------------------------+
| 138 7 348 | 46 346 146 | 9 2 5 |
| 12 125 6 | 257 9 127 | 4 3 8 |
| 9 245 34 | 8 345 24 | 7 1 6 |
|---------------------+--------------------+--------------------|
| 17 3 9 | 467 2 467 | 8 5 14 |
| 178-2 v124 478 | 3 47 5 | p12 6 9 |
| 6 p24 5 | 9 1 8 | 3 7 24 |
|---------------------+--------------------+--------------------|
| 5 9 17 | 2467 467 3 | 126 8 127 |
| 37 6 2 | 1 8 9 | 5 4 37 |
| 4 8 137 | 2567 567 267 | 126 9 1237 |
+---------------------------------------------------------------+
# 65 eliminations remain

<14+2> XYZ-Wing r5c2/r5c7+r6c2 <> 2 r5c1

+--------------------------------------------------------------+
| d138 7 348 | 46 346 c146 | 9 2 5 |
| 2 15 6 | 57 9 17 | 4 3 8 |
| 9 45 34 | 8 345 2 | 7 1 6 |
|--------------------+--------------------+--------------------|
| 7-1 3 9 | 467 2 b467 | 8 5 a14 |
| 178 124 478 | 3 47 5 | 12 6 9 |
| 6 24 5 | 9 1 8 | 3 7 24 |
|--------------------+--------------------+--------------------|
| 5 9 17 | 2467 467 3 | 126 8 127 |
| 37 6 2 | 1 8 9 | 5 4 37 |
| 4 8 137 | 2567 567 67 | 126 9 1237 |
+--------------------------------------------------------------+
# 57 eliminations remain

M-Wing 1B: (1=4)r4c9 - r4c6 = (4-1)r1c6 = (1)r1c1 => r4c1<>1

With respect to the use of XYZ-Wing, I've concluded that it's just Kraken Cell (forcing net) logic with very short chains.

Luke451

Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California

Posted: Sun Mar 04, 2012 4:31 pm Post subject:

From the link posted above by JC:

aran wrote:

One key observation :
I may be wrong but I think that most people would agree that the search for sophisticated and advanced sudoku techniques has been driven by the need to solve sudokus of increasing difficulty.

Put another way : more complex strategies for more complex sudokus. That these strategies are enjoyable in their own right is a separate and different point.
In other words, complexity for its own sake has not been the driving force.

Interesting quote Idea

These days the “more complex strategies” are commonly applied to less complex puzzles.

For example, a long AAIC or almost wing isn’t needed to solve some of our puzzles here, but I’m just learning about these things and enjoy parsing them out when they’re presented by others.

There’s no doubt I have been guilty of steam-rolling, but it’s fun. It helps to be aware of what is possible when one ends up tackling something nastier.

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