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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Nov 24, 2012 8:07 am Post subject: Free Press November 23. 2012 |
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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 |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
Keith |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Nov 24, 2012 3:18 pm Post subject: |
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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: 494
Location: Charleroi, Belgium
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| Posted: Sat Nov 24, 2012 7:34 pm Post subject: |
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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: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Nov 24, 2012 10:14 pm Post subject: |
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| 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: 5770
Location: Rochester, NY, USA
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| Posted: Sun Nov 25, 2012 12:34 am Post subject: |
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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: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Nov 25, 2012 1:24 am Post subject: |
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| 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: 5770
Location: Rochester, NY, USA
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| Posted: Sun Nov 25, 2012 2:19 am Post subject: |
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| 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
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| Posted: Sun Nov 25, 2012 6:45 am Post subject: |
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#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: 1111
Location: Dar es Salaam Tanzania
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| Posted: Sun Nov 25, 2012 6:49 pm Post subject: Free Press November 23, 2012 |
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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 |
+------------+------------+------------+
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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: 494
Location: Charleroi, Belgium
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| Posted: Fri Nov 30, 2012 7:36 am Post subject: |
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| 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: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Nov 30, 2012 10:38 pm Post subject: |
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| 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: 5770
Location: Rochester, NY, USA
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| Posted: Sat Dec 01, 2012 12:36 am Post subject: |
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| 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: 494
Location: Charleroi, Belgium
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| Posted: Sat Dec 01, 2012 9:54 am Post subject: |
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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: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Dec 01, 2012 11:55 am Post subject: |
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| 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? 
or a UP that is not an LS? |
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JC Van Hay
Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
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| Posted: Sat Dec 01, 2012 12:37 pm Post subject: |
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| 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?
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: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Dec 01, 2012 2:44 pm Post subject: |
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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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