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Free Press January 6, 2012
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Fri Jan 06, 2012 4:45 pm    Post subject: Free Press January 6, 2012 Reply with quote
Not yet done.
Code:
Puzzle: FP010612
+-------+-------+-------+
| . . . | . 2 . | 9 . . |
| 1 . . | . 7 . | 8 . 3 |
| . 4 6 | . . . | . 2 7 |
+-------+-------+-------+
| 7 . 8 | . . . | . 5 . |
| . . . | 7 . 4 | . . . |
| . 3 . | . . . | 1 . 2 |
+-------+-------+-------+
| 5 1 . | . . . | 2 9 . |
| 4 . 2 | . 1 . | . . 5 |
| . . 7 | . 4 . | . . . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Fri Jan 06, 2012 8:09 pm    Post subject: Reply with quote
Note: this is Clement's post. I moved it from a separate thread into the original thread started by Keith.

Marty

After the Basics:-
Code:


+----------+--------------+-------------+
| 38 7   5 | 3468 2  368  | 9  146  16  |
| 1  2   9 | 456  7  56   | 8  46   3   |
| 38 4   6 | 1389 89 1389 | 5  2    7   |
+----------+--------------+-------------+
| 7  69  8 | 12   3  12   | 4  5    69  |
| 2  5   1 | 7    69 4    | 36 368  689 |
| 69 3   4 | 689  5  689  | 1  7    2   |
+----------+--------------+-------------+
| 5  1   3 | 68   68 7    | 2  9    4   |
| 4  68  2 | 39   1  39   | 7  68   5   |
| 69 689 7 | 25   4  25   | 36 1368 168 |
+----------+--------------+-------------+

Remote Pairs 69; r9c9<>6 opens an XY-Wing 186 pivoted in r9c9; r12c8<>6 solves it.
_________________
Cnm

Last edited by Marty R. on Fri Jan 06, 2012 8:12 pm; edited 1 time in total
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Fri Jan 06, 2012 8:11 pm    Post subject: Reply with quote
Same as Clement's, except I called the first move a Skyscraper.
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Clement



Joined: 24 Apr 2006
Posts: 1111
Location: Dar es Salaam Tanzania
PostPosted: Fri Jan 06, 2012 8:30 pm    Post subject: Free Press January 6, 2012 Reply with quote
Sorry, my above submission is a reply to keith's Free Press January 6, 2012 Puzzle. It is not a New Topic.I would like if it can be Modified.
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SudoQ



Joined: 02 Aug 2011
Posts: 127
PostPosted: Fri Jan 06, 2012 9:04 pm    Post subject: Reply with quote
You can also show that r5c8<>8 (from r5/9c7=6).
/SudoQ
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
PostPosted: Fri Jan 06, 2012 9:07 pm    Post subject: Reply with quote
Wing : (86)r8c8 6r95c7 3r5c78 : -8r5c8
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Fri Jan 06, 2012 10:30 pm    Post subject: Reply with quote
JC Van Hay wrote:
Wing : (86)r8c8 6r95c7 3r5c78 : -8r5c8

JC, what kind of Wing is that? I can see an AIC where r8c8=6 proves 8 in r5c9.
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Sat Jan 07, 2012 5:50 am    Post subject: Reply with quote
Mutant swordfish on 6, R48C7, nukes a bunch of sixes, but does not solve it.

Keith
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Jan 07, 2012 6:27 pm    Post subject: Reply with quote
There are numerous eliminations present for <6>, including:

Code:
 +--------------------------------------------------------------+
 |  38    7     5     |  3468  2     368   |  9     146   16    |
 |  1     2     9     |  456   7     56    |  8     46    3     |
 |  38    4     6     |  1389  89    1389  |  5     2     7     |
 |--------------------+--------------------+--------------------|
 |  7     69    8     |  12    3     12    |  4     5     69    |
 |  2     5     1     |  7     69    4     | *36   *36+8  689   |
 |  69    3     4     |  689   5     689   |  1     7     2     |
 |--------------------+--------------------+--------------------|
 |  5     1     3     |  68    68    7     |  2     9     4     |
 |  4     68    2     |  39    1     39    |  7    %68    5     |
 |  69    689   7     |  25    4     25    | *36   *36+18 168   |
 +--------------------------------------------------------------+
 # 53 eliminations remain

 r59c78  <36> UR Type 4.2234             <> 6    r59c8   (doesn't crack puzzle)

Fortunately, the <36> UR has an alternate elimination that cracks the puzzle.

Code:
 r59c78  <36> UR via s-link + N_Singles  <> 3    r9c8    (using r8c8)

It uses the following assignments to force the <36> DP into the UR cells:

Code:
r9c8=3 r9c7=6 r8c8=8 r5c8=6 r5c7=3
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Sat Jan 07, 2012 8:46 pm    Post subject: Reply with quote
-8 in R9C9 solves it. Rolling Eyes

Keith
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Sun Jan 08, 2012 5:06 pm    Post subject: Reply with quote
An almost xy-wing(68-3)r58c8+r9c7 = (6)r5c8-r4c9=r4c2-r6c1=r9c1-(6=3)r9c7; r5c7,r9c8<>3

Ted
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
PostPosted: Sun Jan 08, 2012 9:28 pm    Post subject: Reply with quote
Marty R. wrote:
JC Van Hay wrote:
Wing : (86)r8c8 6r95c7 3r5c78 : -8r5c8

JC, what kind of Wing is that? I can see an AIC where r8c8=6 proves 8 in r5c9.
Marty,

An elimination results from a wing of the simplest kind if it can be justified by using 3 members of the B(ivalues)/B(ilocals)-Plot according to the following logical structure :

    If aA, bB and cC are members of the B/B-Plot, b(true)=>a(true) and B(true)=>C(true), then any candidate z seeing a and C can be eliminated.

      In Eureka notation : [z-]a=A-b=B-c=C[-z] => -z or z false

      In short : aA bB cC => -z [pincer* pivot *pincer => elimination]
As to the namings, one could call bB the pivot while the cells containing a and C (or perhaps more simply a and C) the pincers of the wing.
However the naming of the kind of wing is somewhat useless because of the 2x2x2=8 possible combinations of bivalues and bilocals and the number of digits (from 1 to 3) permitted by each combination.

So, in the present case, the wing contains 1 bivalue and 2 bilocals; 3 digits are involved; the bilocal 6r95c7 is the pivot, [8]r8c8 and [5]r5c8 are the pincers.
It is easyly seen that r9c7=6 => r8c8=8 and r5c7=6 => r5c8=3. Therefore, r5c8<>8 as 8r5c8 sees 8r8c8 (same digit in the same unit) and 3r5c8 (same cell).

Best Regards, JC

PS : In the more general sense, an elimination could be said as resulting from a wing if it can be justified by using a 3x3 (Mixed Block or not) Forbidding Matrix. But that is another story. Exclamation Very Happy
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
PostPosted: Mon Jan 09, 2012 2:45 am    Post subject: Reply with quote
JC Van Hay wrote:
In Eureka notation : [z-]a=A-b=B-c=C[-z] => -z or z false

Thanks JC Very Happy
I am seeing wings in a whole new light! Is this correct?
Code:
+----------+--------------+-------------+
| 38 7   5 | 3468 2  368  | 9  146  16  |
| 1  2   9 | 456  7  56   | 8  46   3   |
| 38 4   6 | 1389 89 1389 | 5  2    7   |
+----------+--------------+-------------+
| 7  69  8 | 12   3  12   | 4  5    69  |
| 2  5   1 | 7    69 4    |*36c36-8 689 |
| 69 3   4 | 689  5  689  | 1  7    2   |
+----------+--------------+-------------+
| 5  1   3 | 68   68 7    | 2  9    4   |
| 4  68  2 | 39   1  39   | 7 a68   5   |
| 69 689 7 | 25   4  25   |b36 1368 168 |
+----------+--------------+-------------+
xy-wing
(8=6)r8c8-(6=3)r7-(3=8)b6 => r5c8<>8
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ronk



Joined: 07 May 2006
Posts: 398
PostPosted: Mon Jan 09, 2012 4:08 am    Post subject: Reply with quote
JC Van Hay wrote:
Wing : (86)r8c8 6r95c7 3r5c78 : -8r5c8
arkietech wrote:
xy-wing
(8=6)r8c8-(6=3)r7-(3=8)b6 => r5c8<>8

What happened to ... (8=6)r8c8 - (6)r9c7 = (6-3)r5c7 = (3)r5c8 => r5c8<>8
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Mon Jan 09, 2012 8:36 am    Post subject: Reply with quote
JC Van Hay wrote:
Wing : (86)r8c8 6r95c7 3r5c78 : -8r5c8

My interpretation: 3-SIS => "wing" to JC

Code:
3-SIS: (8=6)r8c8 - (6)r9c7=(6)r5c7 - (3)r5c7=(3)r5c8 => r5c8<>8

After notational condensation: ronk's chain

Code:
3-SIS: (8=6)r8c8 - (6)r9c7 = (6-3)r5c7 = (3)r5c8 => r5c8<>8

arkietech: I think your chain is incorrect.

JC Van Hay: I appreciate that you now identify (ordered) cells instead of base units. Much easier to follow!

Regards, Danny
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arkietech



Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
PostPosted: Mon Jan 09, 2012 12:44 pm    Post subject: Reply with quote
daj95376 wrote:
arkietech: I think your chain is incorrect.

Danny,

Consider this:
Code:
(8=6)r8c8-(6=3)r7-(3=8)b6 =>
(8=6)r8c8-(6=3)r9c7-(3=6)r5c7-(6=3)r5c8 => r5c8<>8
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Mon Jan 09, 2012 5:11 pm    Post subject: Reply with quote
[Withdrawn: too much to address after ronk's comments]

Last edited by daj95376 on Mon Jan 09, 2012 5:38 pm; edited 3 times in total
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ronk



Joined: 07 May 2006
Posts: 398
PostPosted: Mon Jan 09, 2012 5:12 pm    Post subject: Reply with quote
arkietech wrote:
Consider this:
Code:
(8=6)r8c8-(6=3)r9c7-(3=6)r5c7-(6=3)r5c8 => r5c8<>8

You're fine until the last strong inference, which should be (6=3|8)r5c8, which means ... if r5c8<>6, then r5c8=3 or r5c8=8. If the former, r5c8<>8 as you say. If the latter, we have a derived strong inference (8)r8c8=(8)r5c8, which merely duplicates an existing native strong inference. Taken together, the entire AIC then implies nothing useful. However ..

(3&6=8)r5c78 - (8=6)r8c8 - (6=3)r9c7 - (3=6)r5c7 ==> r5c59, r4c9<>6
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
PostPosted: Mon Jan 09, 2012 8:02 pm    Post subject: Reply with quote
arkietech wrote:
... Is this correct?
Code:
+----------+--------------+-------------+
| 38 7   5 | 3468 2  368  | 9  146  16  |
| 1  2   9 | 456  7  56   | 8  46   3   |
| 38 4   6 | 1389 89 1389 | 5  2    7   |
+----------+--------------+-------------+
| 7  69  8 | 12   3  12   | 4  5    69  |
| 2  5   1 | 7    69 4    |*36c36-8 689 |
| 69 3   4 | 689  5  689  | 1  7    2   |
+----------+--------------+-------------+
| 5  1   3 | 68   68 7    | 2  9    4   |
| 4  68  2 | 39   1  39   | 7 a68   5   |
| 69 689 7 | 25   4  25   |b36 1368 168 |
+----------+--------------+-------------+
xy-wing
(8=6)r8c8-(6=3)r7-(3=8)b6 => r5c8<>8


Dan,

Yes, it is correct. Your "xy"-wing is made up of 2 bivalues (native SIS), (68)r8c8 and (36)r9c7, and 1 pseudo-bivalue (derived SIS), (38)r5c79, coming from the observation of 3r5c7=(3-8)r5c8=8r5c9 => 3r5c7=8r5c9 or (3=8)r5c79 or (3=8)b6.

Best Regards, JC
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ronk



Joined: 07 May 2006
Posts: 398
PostPosted: Mon Jan 09, 2012 9:53 pm    Post subject: Reply with quote
JC Van Hay wrote:
Your "xy"-wing is made up of 2 bivalues (native SIS), (68)r8c8 and (36)r9c7, and 1 pseudo-bivalue (derived SIS), (38)r5c79, coming from the observation of 3r5c7=(3-8)r5c8=8r5c9 => 3r5c7=8r5c9 or (3=8)r5c79 or (3=8)b6.

Laughing Good joke! However, if there wasn't a cannibalistic exclusion within the pseudo-bivalue, then ...
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