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Puzzle 10/09/27: D

 
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Mon Sep 27, 2010 8:46 pm    Post subject: Puzzle 10/09/27: D Reply with quote

Clearing out the difficult puzzles.

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

Play this puzzle online at the Daily Sudoku site
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JC Van Hay



Joined: 13 Jun 2010
Posts: 360
Location: Charleroi, Belgium

PostPosted: Tue Sep 28, 2010 9:57 am    Post subject: Reply with quote

Quote:
X Wing (7)C17 : => r39c25<>7
Finned X Wing (7)R28 : r7c4<>7
XY Wing Style, pivot at (76)R9C7 : (7)r7c2=(5)r9c2 : => r7c2<>5
Empty Rectangle (8)R6B1 : => r3c7<>8
BUG +1 : => r3c6=8
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue Sep 28, 2010 11:26 am    Post subject: Reply with quote

Four steps - but nothing too painful!
Quote:
x-wing(7) ; r3c2<>7, r9c25<>7
xy-wing(56-3) r9c2 ; r9c1<>3, r7c46<>3
flightless xy-wing(89-5) r3c2 with transport ; (5=9)r3c9 - (9=8)r3c2 - (8=5)r6c2 - r5c1=r5c4 - r4c5=r1c5 ; r1c9<>5, r3c6<>5
BUG+1 ; r2c8=8
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Sep 28, 2010 4:28 pm    Post subject: Reply with quote

This puzzle was not intended to be a single-stepper. JC and Peter found realistic solutions.

However, I was using this puzzle as a test for clearing up redundancies between my chain() routine and my network() routine. As a check, I tested the first SIN listed by my network() routine. I'm sharing it because it can be interpreted as a chain with a fin cell.

Code:
 after basics
 +-----------------------------------------------------------------------+
 |  6      789    4      |  13578 g3578   358    |  2      18     59     |
 |  2      3      5      |  1678   9     h68     |  4      168   i67     |
 | a78     789    1      |  2      4      568    | @678    3      59     |
 |-----------------------+-----------------------+-----------------------|
 | b589    4      7      |  358   f358    2      | e568    689    1      |
 | b589    1      2      |  58     6      7      |  3      89     4      |
 | b358   c568    36     |  9      1      4      | d58     7      2      |
 |-----------------------+-----------------------+-----------------------|
 |  1      567    36     |  35678  2      3568   |  9      4      367    |
 |  4      2      8      |  367    37     9      |  1      5      367    |
 |  357    567    9      |  4      357    1      |  67     2      8      |
 +-----------------------------------------------------------------------+
 # 72 eliminations remain

Either,

Code:
r3c7=8  =>  r3c7<>7

or r3c7<>8 allowing

Code:
(7=8)r3c1 - r456c1 = r6c2 - r6c7 = (8)r4c7 - r4c5 = r1c5 - (8=6)r2c6 - (6=7)r2c9  =>  r3c7<>7
_____________________________________________________________________________________________

This can be expressed as a SIN-type network:

Code:
            ............. - r3c7
          /                      \
(7=8)r3c1 - r456c1 = r6c2 - r6c7 = (8)r4c7 - r4c5 = r1c5 - (8=6)r2c6 - (6=7)r2c9  =>  r3c7<>7
_____________________________________________________________________________________________

Regards, Danny
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Marty R.



Joined: 12 Feb 2006
Posts: 5061
Location: Rochester, NY, USA

PostPosted: Tue Sep 28, 2010 9:55 pm    Post subject: Reply with quote

X-Wing (7)
Skyscraper (7)
W-Wing (36)
DP 59-58-89; r1c6, r2c4<>8
XY-Wing (563)
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Luke451



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

PostPosted: Wed Sep 29, 2010 12:53 am    Post subject: Reply with quote

daj95376 wrote:
This puzzle was not intended to be a single-stepper. JC and Peter found realistic solutions.

However, I was using this puzzle as a test for clearing up redundancies between my chain() routine and my network() routine. As a check, I tested the first SIN listed by my network() routine. I'm sharing it because it can be interpreted as a chain with a fin cell.

Code:
 after basics
 +-----------------------------------------------------------------------+
 |  6      789    4      |  13578 g3578   358    |  2      18     59     |
 |  2      3      5      |  1678   9     h68     |  4      168   i67     |
 | a78     789    1      |  2      4      568    | @678    3      59     |
 |-----------------------+-----------------------+-----------------------|
 | b589    4      7      |  358   f358    2      | e568    689    1      |
 | b589    1      2      |  58     6      7      |  3      89     4      |
 | b358   c568    36     |  9      1      4      | d58     7      2      |
 |-----------------------+-----------------------+-----------------------|
 |  1      567    36     |  35678  2      3568   |  9      4      367    |
 |  4      2      8      |  367    37     9      |  1      5      367    |
 |  357    567    9      |  4      357    1      |  67     2      8      |
 +-----------------------------------------------------------------------+
 # 72 eliminations remain

Either,

Code:
r3c7=8  =>  r3c7<>7

or r3c7<>8 allowing

Code:
(7=8)r3c1 - r456c1 = r6c2 - r6c7 = (8)r4c7 - r4c5 = r1c5 - (8=6)r2c6 - (6=7)r2c9  =>  r3c7<>7
_____________________________________________________________________________________________

This can be expressed as a SIN-type network:

Code:
            ............. - r3c7
          /                      \
(7=8)r3c1 - r456c1 = r6c2 - r6c7 = (8)r4c7 - r4c5 = r1c5 - (8=6)r2c6 - (6=7)r2c9  =>  r3c7<>7
_____________________________________________________________________________________________

Regards, Danny


Hi, Danny. I stopped by and saw your SIN, v cool. Why this isn't done more often is kind of baffling. A year ago there were relatively few AICs posted here, but today they are commonplace. It seems reasonable that more players would adopt the use of SINs in their chains, but it hasn't happened. (Well, maybe I saw Ted go there a while back Smile)

To me, a "Single Implication Network" will always be "chain memory" as suggested by our friend aran. The concept is simplicity itself: remember where you've been and take advantage of the implications. From my notes, here are some of his quotes on the subject:

aran wrote:
“The idea is this : anything already placed in a developing chain can be remembered (if useful) further down the line in that chain.”

“(It’s) just memory and it's common sense : if you have placed something in a chain it can be remembered later on subject to
i) being appropriate : ie it must be in a peer relationship.”

“Memory can just about be called a net: the simplest form of net life possible, with secondary implication stream(s) of one link only (ie 'seeing')."

Sorry to have lost the origin of these quotes in the Players crash, but they probably can be found quite easily with an advanced search.

I've always liked the idea of memory/SINs. It is a fantastic way to reduce cells to bivalues, or reveal a strong link as you did in the example above. This idea is OVERLOOKED and UNDER-USED and I'm glad to see you point it out!
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Wed Sep 29, 2010 1:55 am    Post subject: Reply with quote

Luke451 wrote:
To me, a "Single Implication Network" will always be "chain memory" as suggested by our friend aran.

Thanks for the positive feedback. SIN is the only network feature (currently) employed in my solver.
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oaxen



Joined: 10 Jul 2006
Posts: 96

PostPosted: Wed Sep 29, 2010 8:45 am    Post subject: One stepper Reply with quote

With chain technique a 6 in r9c2 makes it a one stepper. Going syncronized out from the other 6 in r9 gives very soon many "must bee´s"
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