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Free Press December 23, 2011

 
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Fri Dec 23, 2011 8:24 pm    Post subject: Free Press December 23, 2011 Reply with quote

Not yet started:
Code:
Puzzle: FP122311
+-------+-------+-------+
| . . . | . 7 . | . . 9 |
| . . 6 | . . 2 | . 8 . |
| . 9 . | . . . | . . 1 |
+-------+-------+-------+
| . . . | . 3 5 | 8 9 . |
| 9 . . | . . . | . . 7 |
| . 3 4 | . . . | 2 . . |
+-------+-------+-------+
| 8 . . | 1 . . | . 7 . |
| . 4 . | 6 . . | 5 . . |
| 7 . . | . 5 . | . . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Sat Dec 24, 2011 12:20 am    Post subject: Reply with quote

Looking at the potential 35 DP in boxes 12, one of r13c1=4 or r3c4=8. Common outcome; r1c3, r2c2, r3c3=172.

Code:

+-----------+------------+----------+
| 345 8  12 | 35  7  146 | 46  25 9 |
| 45  17 6  | 59  19 2   | 47  8  3 |
| 345 9  27 | 358 68 468 | 467 25 1 |
+-----------+------------+----------+
| 2   17 17 | 4   3  5   | 8   9  6 |
| 9   5  8  | 2   16 16  | 3   4  7 |
| 6   3  4  | 7   89 89  | 2   1  5 |
+-----------+------------+----------+
| 8   6  5  | 1   4  3   | 9   7  2 |
| 1   4  9  | 6   2  7   | 5   3  8 |
| 7   2  3  | 89  5  89  | 1   6  4 |
+-----------+------------+----------+

Play this puzzle online at the Daily Sudoku site
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Dec 24, 2011 5:56 am    Post subject: Reply with quote

Marty R. wrote:
Looking at the potential 35 DP in boxes 12, one of r13c1=4 or r3c4=8. Common outcome; r1c3, r2c2, r3c3=172.

Code:

+-----------+------------+----------+
| 345 8  12 | 35  7  146 | 46  25 9 |
| 45  17 6  | 59  19 2   | 47  8  3 |
| 345 9  27 | 358 68 468 | 467 25 1 |
+-----------+------------+----------+
| 2   17 17 | 4   3  5   | 8   9  6 |
| 9   5  8  | 2   16 16  | 3   4  7 |
| 6   3  4  | 7   89 89  | 2   1  5 |
+-----------+------------+----------+
| 8   6  5  | 1   4  3   | 9   7  2 |
| 1   4  9  | 6   2  7   | 5   3  8 |
| 7   2  3  | 89  5  89  | 1   6  4 |
+-----------+------------+----------+

Play this puzzle online at the Daily Sudoku site
Marty,

I don't like your solution, if you don;t mind me saying so. When I run R3C4=8, I get different results in the three cells you mention.

Now, certainly, R13C4=4 and/or R3C4=8. After any number of steps, and by any path, if you can show (for example) that R1C3=1, then indeed R3C1=1.

However, you can also assume R3C4=8 and show R3C1=2.

Let me put is in a different way. I don't like your solution for the same reason I believe you would not like the Almost Naked Pair 35 in R13C4.

Since I do also not like chains that are not patterns, I now have a problem.

Bah! Humbug!

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Sat Dec 24, 2011 6:18 am    Post subject: Reply with quote

Quote:
When I run R3C4=8, I get different results in the three cells you mention.

Keith, I stand by my solution. An 8 in r3c4 yields a 7 in r3c7 and 2 in r3c3.
Quote:
I don't like your solution, if you don;t mind me saying so.

I don't mind you saying so at all. And if my statement above is incorrect, I'd want to know about it. I always want input if it's not an insult and has the potential to improve my game.

I'd have probably been happier with some other solution, but I have to do what I have to do in order to solve puzzles.

But just for the sake of argument, a couple of years ago I asked you about a UR you used, claiming that it looked like a Forcing Chain which you were led to by a potential UR. You replied that you saw nothing wrong with spotting a pattern and then examining the ramifications of that pattern. Is that or is that not what I did?

At any rate, I'll say the same thing you said, that I hope you don't mind me saying what I said. I'm heading to bed but look forward to your reply Saturday.

Cheers!
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Sat Dec 24, 2011 7:20 am    Post subject: Reply with quote

Hmmm!!! First off, my solver yields a more complex grid after basics.

Code:
 after basics
 +-----------------------------------------------------+
 | *35+4 8    12   | *35   7    146  |  46   25   9    |
 |  45   17   6    |  59   149  2    |  47   8    3    |
 | *35+4 9    27   | *35+8 468  468  |  467  25   1    |
 |-----------------+-----------------+-----------------|
 |  2    17   17   |  4    3    5    |  8    9    6    |
 |  9    5    8    |  2    16   16   |  3    4    7    |
 |  6    3    4    |  7    89   89   |  2    1    5    |
 |-----------------+-----------------+-----------------|
 |  8    6    5    |  1    24   3    |  9    7    24   |
 |  1    4    9    |  6    28   7    |  5    3    28   |
 |  7    2    3    |  89   5    489  |  1    6    48   |
 +-----------------------------------------------------+
 # 40 eliminations remain

You can use Marty's sequence:

(8)r3c4 - (8=467)r3c567 - (7=2)r3c3

And then derive:

(4)r13c1 - (4=5=9*=8=2=4)r2c1,r2c4,r9c4,r8c5,r7c5 - (*94=1)r2c5 - (1=7=2)r2c2,r3c3

Or you can use the contradiction to Marty's sequence:

(8)r3c4 - (8=461)r3c56,r1c6 - (1=2)r1c3

And create a single chain:

(8=461)r3c56,r1c6 - (1=2=7)r1c3,r3c3 - (746=8)r3c756 => r3c4<>8

The remaining UR Type 2 cracks the puzzle.
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SudoQ



Joined: 02 Aug 2011
Posts: 127

PostPosted: Sat Dec 24, 2011 8:41 am    Post subject: Reply with quote

If you like chains, it is easy to show that
r2c4=5 leads to a contradiction in r1(c7).

/SudoQ
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JC Van Hay



Joined: 13 Jun 2010
Posts: 364
Location: Charleroi, Belgium

PostPosted: Sat Dec 24, 2011 8:48 am    Post subject: Reply with quote

A chain : "Wing" : ANP(9=45)r2c14-AHP(4r1c1=46r1c67)-1r1c6=1r2c5 => -9r2c5;stte

or

A pattern : ALS-XZ Rule : (X=1,Z=4) : ANP(4=17)r2c27-ANQ(1=2345)r1c1348 => -4r1c7, -4r2c1;stte
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arkietech



Joined: 31 Jul 2008
Posts: 1708
Location: Northwest Arkansas USA

PostPosted: Sat Dec 24, 2011 4:40 pm    Post subject: Reply with quote

JC Van Hay wrote:
A pattern : ALS-XZ Rule : (X=1,Z=4) : ANP(4=17)r2c27-ANQ(1=2345)r1c1348 => -4r1c7, -4r2c1;stte


Thanks JC,
I have struggled with this for a long time. You turned lights on for me.
Code:
 *--------------------------------------------------*
 |a345  8   a12   |a35   7    146  | 6-4 a25   9    |
 | 5-4 b17   6    | 59   149  2    |b47   8    3    |
 | 345  9    27   | 358  468  468  | 467  25   1    |
 |----------------+----------------+----------------|
 | 2    17   17   | 4    3    5    | 8    9    6    |
 | 9    5    8    | 2    16   16   | 3    4    7    |
 | 6    3    4    | 7    89   89   | 2    1    5    |
 |----------------+----------------+----------------|
 | 8    6    5    | 1    24   3    | 9    7    24   |
 | 1    4    9    | 6    28   7    | 5    3    28   |
 | 7    2    3    | 89   5    489  | 1    6    48   |
 *--------------------------------------------------*
als-xz(x=1,z=4):anq(1=2345)r1c1348-anp(4=17)r2c27 => r1c7,r2c1<>4

(1)a=(4)b;r2c7=4;
(1)b=(4)a;r1c1=4; => r1c7,r2c1<>4
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Sat Dec 24, 2011 4:51 pm    Post subject: Reply with quote

Quote:
Hmmm!!! First off, my solver yields a more complex grid after basics.

Danny, I did this three times (once with pencil and paper and twice on Draw/Play) and got three different post-basics grids. However, on my last attempt (on Draw/Play) it agreed with yours. Embarassed
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Sat Dec 24, 2011 5:02 pm    Post subject: Reply with quote

Use of an atypical UR strong inference.

Code:
 after basics
 +-----------------------------------------------------+
 | *35+4 8    12   | *35   7    146  |  6-4  25   9    |
 |  5-4  17   6    |  59   149  2    |  47   8    3    |
 | *35+4 9    27   | *35+8 468  468  |  467  25   1    |
 |-----------------+-----------------+-----------------|
 |  2    17   17   |  4    3    5    |  8    9    6    |
 |  9    5    8    |  2    16   16   |  3    4    7    |
 |  6    3    4    |  7    89   89   |  2    1    5    |
 |-----------------+-----------------+-----------------|
 |  8    6    5    |  1    24   3    |  9    7    24   |
 |  1    4    9    |  6    28   7    |  5    3    28   |
 |  7    2    3    |  89   5    489  |  1    6    48   |
 +-----------------------------------------------------+
 # 40 eliminations remain

 (4=7)r2c7 - (7=468)r3c567 - (48)r3c14 =UR= (4)r1c1  =>  r1c7,r2c1<>4
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arkietech



Joined: 31 Jul 2008
Posts: 1708
Location: Northwest Arkansas USA

PostPosted: Sat Dec 24, 2011 6:27 pm    Post subject: Reply with quote

More als views

als xy=wing
Code:
 *--------------------------------------------------*
 |a345  8   a12   |a35   7    146  | 6-4 a25   9    |
 | 5-4 c17   6    | 59   149  2    |b47   8    3    |
 | 345  9    27   | 358  468  468  | 467  25   1    |
 |----------------+----------------+----------------|
 | 2    17   17   | 4    3    5    | 8    9    6    |
 | 9    5    8    | 2    16   16   | 3    4    7    |
 | 6    3    4    | 7    89   89   | 2    1    5    |
 |----------------+----------------+----------------|
 | 8    6    5    | 1    24   3    | 9    7    24   |
 | 1    4    9    | 6    28   7    | 5    3    28   |
 | 7    2    3    | 89   5    489  | 1    6    48   |
 *--------------------------------------------------*
als-xy-wing(xy=17):anq(1=2345)r1c1348-(4=7)r2c7-(7=1)r2c2 => r1c7,r2c1<>4

(1)a=(7)c=(4)b;r2c7=4;
(7)b=(1)c=(4)a;r1c1=4; => r1c7,r2c1<>4

And then an als-chain
Code:
 *--------------------------------------------------*
 |a345  8   a12   |b35   7    146  | 6-4 b25   9    |
 | 5-4 d17   6    | 59   149  2    |c47   8    3    |
 | 345  9    27   | 358  468  468  | 467  25   1    |
 |----------------+----------------+----------------|
 | 2    17   17   | 4    3    5    | 8    9    6    |
 | 9    5    8    | 2    16   16   | 3    4    7    |
 | 6    3    4    | 7    89   89   | 2    1    5    |
 |----------------+----------------+----------------|
 | 8    6    5    | 1    24   3    | 9    7    24   |
 | 1    4    9    | 6    28   7    | 5    3    28   |
 | 7    2    3    | 89   5    489  | 1    6    48   |
 *--------------------------------------------------*
als-chain:ant(4=35)r1c14-ant(5=12)r1c38-(1=7)r2c2-(7=4)r2c7 => r1c7,r2c1<>4

I like better

(4=35)r1c14-(5=12)r1c38-(1=7)r2c2-(7=4)r2c7 => r1c7,r2c1<>4
edit typo

Last edited by arkietech on Sat Dec 24, 2011 9:11 pm; edited 1 time in total
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Dec 24, 2011 8:50 pm    Post subject: Reply with quote

For what it's worth. After basics:
Code:
+-------------+-------------+-------------+
| 345 8  D12  | 35  7   146 | 46 C25  9   |
|c45 e17  6   |b59  149 2   |d47  8   3   |
|A345 9   27  |*358 468 468 |467 B25  1   |
+-------------+-------------+-------------+
| 2   17  17  | 4   3   5   | 8   9   6   |
| 9   5   8   | 2   16  16  | 3   4   7   |
| 6   3   4   | 7   89  89  | 2   1   5   |
+-------------+-------------+-------------+
| 8   6   5   | 1   24  3   | 9   7   24  |
| 1   4   9   | 6   28  7   | 5   3   28  |
| 7   2   3   |a89  5   489 | 1   6   48  |
+-------------+-------------+-------------+

If R3C4=8:
1) Cell a=9; b=5; c=4; d=7; e=1.
and
2) Cell A=3; B=5; C=2; D=1.

D and e cannot both be 1. Thus, R3C4<>8, and the puzzle is solved.

What follows is simply my opinion:

There's nothing wrong with this solution, I just don't like it. And, the longer the implication chains, the more I dislike it.

Sure, you can justify looking at whether R3C4=8 because of the UR, or because of the almost pair 35 in C4, but remember: Every bivalue cell is a finned single, or an "almost" single. Yet I would regard an almost single as simple trial and error.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Sat Dec 24, 2011 10:49 pm    Post subject: Reply with quote

Keith,

If you have a Type 3, say, AB-AB-ABC-ABD, do you not look at the implications of C and D being true? How is that different from the UR here?

By the way, I also found that r3c4=8 leads to an invalidity. But here I've fallen under the influence of Ronk who has posited that common outcomes are more satisfying than invalidities. Thus, I didn't use the invalidity, rather I extended the chain to achieve a common outcome.

I agree that shorter chains are more satisfying than longer ones, but I had no choice. All the other posters are using ALS's or various Eureka-notated solutions which I don't understand.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Sat Dec 24, 2011 11:28 pm    Post subject: Reply with quote

Marty,

Go watch the Lions. This is pretty impressive. (I did not watch the Bills.)

Quote:
do you not look at the implications of C and D being true?


Well, actually, it's C or D, though C and D are permitted.

It's the length of the implication chain I find less than satisfying. (Not that there's anything wrong with that.)

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5119
Location: Rochester, NY, USA

PostPosted: Sat Dec 24, 2011 11:51 pm    Post subject: Reply with quote

The Lions weren't on here and the Bills were blacked out so we were offered the Evil Empire (Pats) at 1:00 and the Eagles-Cowboys at 4:00.
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