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Puzzle 10/09/10: C

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Fri Sep 10, 2010 6:56 am    Post subject: Puzzle 10/09/10: C Reply with quote
Code:
 +-----------------------+
 | 7 . . | . . . | . . . |
 | . 4 . | 5 . . | . . 7 |
 | . . 6 | . . . | 5 . . |
 |-------+-------+-------|
 | 8 7 . | . 3 5 | . . . |
 | . . . | 7 . . | 9 . . |
 | . . . | 4 . 8 | . . . |
 |-------+-------+-------|
 | . . . | . 2 . | . . 1 |
 | . 5 . | . . 6 | . . 8 |
 | . 9 . | . . . | 3 2 4 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site


Rating wrote:
XY
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JC Van Hay



Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium
PostPosted: Fri Sep 10, 2010 12:46 pm    Post subject: Reply with quote
Quote:
I successively played the following steps :

1. Skyscraper (8)R39 : r2c3,r7c2<>81.
2. X Wing (8)R79/c34 : r3c4<>8
3. X Chain (2)R5B29 : => r1c2<>2
4. Type 1 UR(35)R56C19 : => r6c1<>35=19
5. M Wing (29) : (29)R2C3 9R4 2B5 : => r2c6<>2
6. Empty Rectangle (9)C3B5 : => r2c5<>9
7. XY Chain : 1C5 6c5 9R6 1R6 : (1)r2cc5=(1)r6c7 : => r2c7<>1

Note : steps 1,2,5 & 6 not necessary.
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Fri Sep 10, 2010 6:22 pm    Post subject: Reply with quote
Two fun steps!
Quote:
kite(2) with transport ; r1c2<>2
Flightless w-wing(12) with transport ; (1=2)r6c7 - r4c7=r4c4 - (2=1)r5c6 transport - (1)r5c5=r2c5 ; r2c7<>1
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Sat Sep 11, 2010 4:01 am    Post subject: Reply with quote
I had numerous steps but I have no insight what was needed.......

Quote:
Type 1 UR35r56c19; r6c1<>35
x-chain (2): (2)r5c2=(2)r5c6-r4c4=r3c4-r3c9=(2)r1c9; r1c2<>2
AUR(34)r13c68 External SIS: r2c6=3, r1c7=4
AUR(34)r13c68[(3)r2c6=(4)r1c4]-(4=3)r1c8; r1c6<>3
(1=9)r4c3-(9=2)r4c4-(2=1)r5c6-r5c5=r2c5-r2c7=(1)r3c8; r4c8<>1

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Sep 11, 2010 11:42 am    Post subject: Reply with quote
tlanglet wrote:
I had numerous steps but I have no insight what was needed.......

I didn't check for which are necessary from my solver.

Code:
 r56c19  <35> UR Type 1.2225             r6c1<>35

 r25\c26 Sashimi X-Wing                  <> 2    r1c2
 r6c3    2-String Kite                   <> 9    r2c5

 +-----------------------------------------------------------------------+
 |  7      1      5      |  6      89     2349   |  48     34     29     |
 |  239    4      29     |  5      18     239    |  18     6      7      |
 |  239    8      6      |  129    7      12349  |  5      134    29     |
 |-----------------------+-----------------------+-----------------------|
 |  8      7      19     |  29     3      5      |  124    14     6      |
 |  5      26     4      |  7      16     12     |  9      8      3      |
 |  19     26     3      |  4      69     8      |  12     7      5      |
 |-----------------------+-----------------------+-----------------------|
 |  4      3      78     |  89     2      79     |  6      5      1      |
 |  12     5      12     |  3      4      6      |  7      9      8      |
 |  6      9      78     |  18     5      17     |  3      2      4      |
 +-----------------------------------------------------------------------+
 # 45 eliminations remain

 M-Wing 7A (1=2)r5c6 - r4c4   = (2-1)r3c4 = (1)r9c4  =>  r9c6<>1   -or-
 M-Wing 7B (1=2)r5c6 - r123c6 = (2-1)r3c4 = (1)r9c4  =>  r9c6<>1

         BUG+1                           =  1    r4c7

As for URs, I have (but didn't use):

Code:
 r13c69  <29> UR via s-link              <> 9    r3c6
 r13c68  <34> UR via s-link              <> 3    r3c6
 r13c68  <34> UR via s-link              <> 4    r1c8
 r13c68  <34> UR via s-link              <> 3    r1c6   extraneous
 r13c68  <34> UR via s-link              <> 3    r3c8   extraneous

I tried my best to make the following 2349 DP work in [band 1], but r2c3 seemed to ruin it.
Too bad because the elimination was comparable to the M-Wing.

Code:
 +-----------------------------------------------------------------------+
 |  7      1      5      |  6      89    *2349   |  48    *34    *29     |
 | *239    4      29     |  5      18    *239    |  18     6      7      |
 | *239    8      6      |  29-1   7     *2349+1 |  5     *34+1  *29     |
 |-----------------------+-----------------------+-----------------------|
 |  8      7      19     |  29     3      5      |  124    14     6      |
 |  5      26     4      |  7      16     12     |  9      8      3      |
 |  19     26     3      |  4      69     8      |  12     7      5      |
 |-----------------------+-----------------------+-----------------------|
 |  4      3      78     |  89     2      79     |  6      5      1      |
 |  12     5      12     |  3      4      6      |  7      9      8      |
 |  6      9      78     |  18     5      17     |  3      2      4      |
 +-----------------------------------------------------------------------+
 # 45 eliminations remain
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Sat Sep 11, 2010 2:05 pm    Post subject: Reply with quote
daj95376 wrote:

I tried my best to make the following 2349 DP work in [band 1], but r2c3 seemed to ruin it.
Too bad because the elimination was comparable to the M-Wing.

Code:
 +-----------------------------------------------------------------------+
 |  7      1      5      |  6      89    *2349   |  48    *34    *29     |
 | *239    4      29     |  5      18    *239    |  18     6      7      |
 | *239    8      6      |  29-1   7     *2349+1 |  5     *34+1  *29     |
 |-----------------------+-----------------------+-----------------------|
 |  8      7      19     |  29     3      5      |  124    14     6      |
 |  5      26     4      |  7      16     12     |  9      8      3      |
 |  19     26     3      |  4      69     8      |  12     7      5      |
 |-----------------------+-----------------------+-----------------------|
 |  4      3      78     |  89     2      79     |  6      5      1      |
 |  12     5      12     |  3      4      6      |  7      9      8      |
 |  6      9      78     |  18     5      17     |  3      2      4      |
 +-----------------------------------------------------------------------+
 # 45 eliminations remain


Danny,

So what do you mean by "work"? If your pattern is a valid ADP, then you found r3c4<>1 and it "worked" . Confused

Ted
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sat Sep 11, 2010 5:16 pm    Post subject: Reply with quote
tlanglet wrote:
So what do you mean by "work"? If your pattern is a valid ADP, then you found r3c4<>1 and it "worked" . Confused

Yet another example of my choosing the wrong words.

What I was trying to say is that I don't know if I have a valid DP, but the elimination "works" even if the logic is faulty. I was hoping someone would say that the DP was valid and that my concern over cell r2c3 was unfounded. Otherwise, it was a "lucky" elimination.

Regards, Danny
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK
PostPosted: Sat Sep 11, 2010 6:12 pm    Post subject: Reply with quote
I am by no means experienced in these DPs .. so take this with a large pinch of salt!

...but my understanding was that a test was - could you collapse the potential deadly pattern into a single solution by potential solutions in external cells. If you can only get a zero-solution situation then it is a deadly pattern, if you can get a single solution it isn't (even if the external cells don't actually solve to those values). There is a discussion somewhere on permeable and impermeable versions of this - not sure what that means!

Just plugging your DP into SS, removing the candidate 1s that prevent it and then seeing if it can be collapsed, I found..

Set r2c3=2 and r7c6=9 (allow invalid moves) and then single step through and the deadly pattern collapses... so I think that means it is not deadly.

Look forward to someone more knowledgeable on this!
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