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Free Press November 23. 2012

 
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sat Nov 24, 2012 8:07 am    Post subject: Free Press November 23. 2012 Reply with quote

A little more challenging, perhaps, than the last few:
Code:
Puzzle: FP112312
+-------+-------+-------+
| 8 . . | 4 . . | . . 6 |
| . . 6 | . . 5 | 3 7 4 |
| . . 5 | 7 . . | . . . |
+-------+-------+-------+
| 1 . . | 3 7 . | . . 8 |
| . . . | . . . | . . . |
| 7 . . | . 1 8 | . . 5 |
+-------+-------+-------+
| . . . | . . 4 | 6 . . |
| 3 8 9 | 6 . . | 5 . . |
| 6 . . | . . 3 | . . 2 |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sat Nov 24, 2012 3:18 pm    Post subject: Reply with quote

After basics:
Code:
+----------------+----------------+----------------+
| 8    279  27   | 4    3    129  |C12   5    6    |
| 29   1    6    | 289  89   5    | 3    7    4    |
| 4    3    5    | 7    6   D12   | 128  128  9    |
+----------------+----------------+----------------+
| 1    5    24   | 3    7    269  | 249  269  8    |
|A29   269  8    | 5    4   6-29  | 17   13   37   |
| 7   46-29 3    |B29   1    8    | 249  269  5    |
+----------------+----------------+----------------+
| 5    27   127  | 189  89   4    | 6    389  37   |
| 3    8    9    | 6    2    7    | 5    4    1    |
| 6    47   147  | 189  5    3    | 789  89   2    |
+----------------+----------------+----------------+

AB are a remote pair 29. After that, CD become W-wing pincers on 1.

Keith
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JC Van Hay



Joined: 13 Jun 2010
Posts: 373
Location: Charleroi, Belgium

PostPosted: Sat Nov 24, 2012 7:34 pm    Post subject: Reply with quote

Only "basics" (LS+Nishio) are needed ...

#1. UP45
#2. EmptyRectangle(29C1B2); UP51
#3. EmptyRectangle(2R4B3); UP81
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sat Nov 24, 2012 10:14 pm    Post subject: Reply with quote

JC Van Hay wrote:
Only "basics" (LS+Nishio) are needed ...

#1. UP45
#2. EmptyRectangle(29C1B2); UP51
#3. EmptyRectangle(2R4B3); UP81

JC,

I can read Dutch fairly well, but I have no idea what you mean.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5181
Location: Rochester, NY, USA

PostPosted: Sun Nov 25, 2012 12:34 am    Post subject: Reply with quote

I struggled to a three-step solution.

Skyscraper on 2, W-Wing on 29 and Finned X-Wing on 2.

How did you make eliminations on 2? I saw a W-Wing connected by SL 2 with 9s getting eliminated. Also, what move was made to get the pincers on 1?
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sun Nov 25, 2012 1:24 am    Post subject: Reply with quote

Marty R. wrote:
I struggled to a three-step solution.

Skyscraper on 2, W-Wing on 29 and Finned X-Wing on 2.

How did you make eliminations on 2? I saw a W-Wing connected by SL 2 with 9s getting eliminated. Also, what move was made to get the pincers on 1?


Marty,

I don't know where we are missing the point, so please forgive this detailed explanation:
Code:
+----------------+----------------+----------------+
| 8    279  27   | 4    3    129  | 12   5    6    |
|#29   1    6    |#289  89   5    | 3    7    4    |
| 4    3    5    | 7    6    12   | 128  128  9    |
+----------------+----------------+----------------+
| 1    5    24   | 3    7    269  | 249  269  8    |
|A29   269  8    | 5    4    269  | 17   13   37   |
| 7    2469 3    |B29   1    8    | 249  269  5    |
+----------------+----------------+----------------+
| 5    27   127  | 189  89   4    | 6    389  37   |
| 3    8    9    | 6    2    7    | 5    4    1    |
| 6    47   147  | 189  5    3    | 789  89   2    |
+----------------+----------------+----------------+

AB are a remote pair because they can be connected by coloring on one candidate, 2. If you don't want that, they are W-wing pincers on 9 and skyscraper pincers on 2.

(If you don't buy the remote pair by coloring on only one candidate, we need to go back a few years.)

Leading to here:
Code:
+-------------+-------------+-------------+
| 8   279 27  | 4   3  -129 |D12  5   6   |
| 29  1   6   | 289 89  5   | 3   7   4   |
| 4   3   5   | 7   6  C12  |-128 -128 9  |
+-------------+-------------+-------------+
| 1   5   4   | 3   7  *29  |*29  6   8   |
| 29  29  8   | 5   4   6   | 17  13  37  |
| 7   6   3   | 29  1   8   | 4   29  5   |
+-------------+-------------+-------------+
| 5   27  127 | 189 89  4   | 6   389 37  |
| 3   8   9   | 6   2   7   | 5   4   1   |
| 6   4   17  | 189 5   3   | 789 89  2   |
+-------------+-------------+-------------+ 

CD are W-wing pincers on 1, excited by the strong link ** on 2 in R4.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5181
Location: Rochester, NY, USA

PostPosted: Sun Nov 25, 2012 2:19 am    Post subject: Reply with quote

Quote:
(If you don't buy the remote pair by coloring on only one candidate, we need to go back a few years.)


Not sure that I understand that. I didn't think coloring was a requirement to call something Remote Pairs.

When you mentioned Remote Pairs I thought of a W-Wing. However, I saw and played the Skyscraper on 2 and when I transported the 2 from r6c4 to r4c78 it knocked out the 2 from r4c3. However, I still needed the W-Wing on 29 to set up the Finned X-Wing.

I don't see how you got to only two 2s in r4 based on the eliminations shown. But on the other hand, I'm having a pretty bad Sudoku day.
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storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Sun Nov 25, 2012 6:45 am    Post subject: Reply with quote

#1...skyscraper on 2 in columns 1 and 4; r6c2 and r5c6 <> 2
#2...Kite on (9): r5c1 = r2c1 - r1c2 = r1c6; r5c6 <> 9
#3...skyscraper on 2 columns 4 and 8; r3c6 <> 2
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Clement



Joined: 24 Apr 2006
Posts: 686
Location: Dar es Salaam Tanzania

PostPosted: Sun Nov 25, 2012 6:49 pm    Post subject: Free Press November 23, 2012 Reply with quote

M-Wing 29
(9=2)r6c4-r2c4=(2-9)r2c1=(9)r5c1 => r6c2<>9, r5c6<>9 and
Skyscraper on 2 from row 2; r6c2<>2, r5c6<>2 leads to the following grid
Code:

+------------+------------+------------+
| 8  279 27  | 4   3  129 | *12  5   6  |
| 29 1   6   | 289 89 5   | 3   7   4  |
| 4  3   5   | 7   6  *12  | -128 -128 9  |
+------------+------------+------------+
| 1  5   4   | 3   7  29  | 29  6   8  |
| 29 29  8   | 5   4  6   | 17  13  37 |
| 7  6   3   | 29  1  8   | 4   29  5  |
+------------+------------+------------+
| 5  27  127 | 189 89 4   | 6   389 37 |
| 3  8   9   | 6   2  7   | 5   4   1  |
| 6  4   17  | 189 5  3   | 789 89  2  |
+------------+------------+------------+
W-Wing 12 in BOX 23 with SL 2 in row 4; r3c78<>1 solves it.
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JC Van Hay



Joined: 13 Jun 2010
Posts: 373
Location: Charleroi, Belgium

PostPosted: Fri Nov 30, 2012 7:36 am    Post subject: Reply with quote

keith wrote:
JC Van Hay wrote:
Only "basics" (LS+Nishio) are needed ...

#1. UP45
#2. EmptyRectangle(29C1B2); UP51
#3. EmptyRectangle(2R4B3); UP81

JC,

I can read Dutch fairly well, but I have no idea what you mean.

Keith


Only "basics" (LS+Nishio) are needed ...

#1. UP45
#2. EmptyRectangle(29C1B2) : r5c1=r2c1-r2c45=r13c6 :=> -29r5c6 ; UP51
#3. EmptyRectangle(2 R4B3) : r4c6=r4c7-r13c7=r3c8 :=> - 2r3c6 ; UP81
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Fri Nov 30, 2012 10:38 pm    Post subject: Reply with quote

JC Van Hay wrote:
Only "basics" (LS+Nishio) are needed ...

#1. UP45
#2. EmptyRectangle(29C1B2) : r5c1=r2c1-r2c45=r13c6 :=> -29r5c6 ; UP51
#3. EmptyRectangle(2 R4B3) : r4c6=r4c7-r13c7=r3c8 :=> - 2r3c6 ; UP81


I am sorry for being so dense, but what is

a) LS + Nishio ?
b) UP45 ?
c) etc. ?

I might note that JC did not post a grid. His (her?) explanation is presumably self-contained and obvious to everyone but me.

Examples and/or detailed explanations will be appreciated.

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5181
Location: Rochester, NY, USA

PostPosted: Sat Dec 01, 2012 12:36 am    Post subject: Reply with quote

Quote:
His (her?) explanation is presumably self-contained and obvious to everyone but me.


You're not the only one.
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JC Van Hay



Joined: 13 Jun 2010
Posts: 373
Location: Charleroi, Belgium

PostPosted: Sat Dec 01, 2012 9:54 am    Post subject: Reply with quote

Hope this is clearer ...
Code:
+-----------------+---------------------+-----------------+
| 8     1279  127 | 4       3     1(29) | 12    5      6  |
| (29)  129   6   | 18(29)  8(9)  5     | 3     7      4  |
| 4     3     5   | 7       6     1(2)  | 128   128    9  |
+-----------------+---------------------+-----------------+
| 1     5     24  | 3       7     269   | 249   269    8  |
| (29)  269   8   | 5       4     6-29  | 1279  12369  37 |
| 7     2469  3   | 29      1     8     | 249   269    5  |
+-----------------+---------------------+-----------------+
| 5     127   127 | 189     89    4     | 6     389    37 |
| 3     8     9   | 6       2     7     | 5     4      1  |
| 6     147   147 | 189     5     3     | 789   89     2  |
+-----------------+---------------------+-----------------+
45 Singles
Empty Rectangle in C1 and B2 on 2s and 9s : r5c1=r2c1-r2c45=r13c6 :=> -29r5c6
+---------------+----------------+------------------+
| 8   1279  127 | 4     3   129  | 1(2)   5      6  |
| 29  129   6   | 1289  89  5    | 3      7      4  |
| 4   3     5   | 7     6   1-2  | 18(2)  18(2)  9  |
+---------------+----------------+------------------+
| 1   5     4   | 3     7   9(2) | 9(2)   6      8  |
| 29  29    8   | 5     4   6    | 1279   1239   37 |
| 7   6     3   | 29    1   8    | 4      29     5  |
+---------------+----------------+------------------+
| 5   127   127 | 189   89  4    | 6      389    37 |
| 3   8     9   | 6     2   7    | 5      4      1  |
| 6   4     17  | 189   5   3    | 789    89     2  |
+---------------+----------------+------------------+
51 Singles
Empty Rectangle in R4 and B3 on 2s : r4c6=r4c7-r13c7=r3c8  :=> - 2r3c6; ste

"Acronyms ":

UP = Unique Possibilities or Naked Singles plus Hidden Singles
LS = Locked Subsets (Naked and Hidden Singles, Pairs, Triples, ...)
LC = Locked Candidates (Pointing, Claiming)
Nishio = Single Digit Techniques
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arkietech



Joined: 31 Jul 2008
Posts: 1734
Location: Northwest Arkansas USA

PostPosted: Sat Dec 01, 2012 11:55 am    Post subject: Reply with quote

JC Van Hay wrote:

UP = Unique Possibilities or Naked Singles plus Hidden Singles
LS = Locked Subsets (Naked and Hidden Singles, Pairs, Triples, ...)
LC = Locked Candidates (Pointing, Claiming)
Nishio = Single Digit Techniques


What is the difference between an LS and UP? Confused

or a UP that is not an LS?
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JC Van Hay



Joined: 13 Jun 2010
Posts: 373
Location: Charleroi, Belgium

PostPosted: Sat Dec 01, 2012 12:37 pm    Post subject: Reply with quote

arkietech wrote:
JC Van Hay wrote:

UP = Unique Possibilities or Naked Singles plus Hidden Singles
LS = Locked Subsets (Naked and Hidden Singles, Pairs, Triples, ...)
LC = Locked Candidates (Pointing, Claiming)
Nishio = Single Digit Techniques


What is the difference between an LS and UP? Confused

or a UP that is not an LS?


LS=UP+Ntuples, N>1 :=> UP is a subset of LS.
Similarly, LC is a subset of Nishio.

Two references : definitions and my favorite page in SteveK's blog about easy techniques (or "basics"), puzzle markings and strategy.
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keith



Joined: 19 Sep 2005
Posts: 3184
Location: near Detroit, Michigan, USA

PostPosted: Sat Dec 01, 2012 2:44 pm    Post subject: Reply with quote

From Sudopedia:

Nishio
A limited form of Trial & Error where only candidates for a single digit are considered.
Nishio is a slightly controversial solving technique that examines the effects of placing a candidate in a cell on the remaining candidates for the same digit. When a contradiction is found, the tried candidate can be eliminated.
To avoid the smell of Trial & Error, players often perform Nishio moves in reverse. To understand how this works, you need to consider the nature of a Nishio contradiction. It occurs when all the candidates for a house are eliminated, as a result of which the house cannot be completed. In the reverse operation, all the candidates for the conflicting house are tried in turn. In each case, the original candidate will be eliminated. Because this proves that there exists no case in which the original candidate can exist, you may eliminate it from the grid.
There is a wide range of single digit solving techniques which diminish the need for Nishio.
Nishio can be replicated by computer programs using templates.
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