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Another M I

 
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Tue Oct 30, 2012 8:28 pm    Post subject: Another M I Reply with quote

Another Menneske Impossible 'that ain't'
Code:

+--------------------+------------------+------------------+
| 5    469    1      | 346  7      3469 | 28    69    28   |
| 8    24679  2469   | 2456 12569  1469 | 157   3     157  |
| 237  2679   2369   | 2568 125689 1689 | 157   69    4    |
+--------------------+------------------+------------------+
| 234  5      7      | 9    1368   1468 | 1238  128   128  |
| 6    1      238    | 578  358    78   | 23578 4     9    |
| 9    48     348    | 4578 1358   2    | 6     1578  1578 |
+--------------------+------------------+------------------+
| 247  246789 245689 | 1    2689   6789 | 24578 2578  3    |
| 1247 3      24689  | 2678 2689   5    | 12478 1278  1278 |
| 127  278    258    | 2378 4      378  | 9     12578 6    |
+--------------------+------------------+------------------+

Play this puzzle online at the Daily Sudoku site

Fred
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JC Van Hay



Joined: 13 Jun 2010
Posts: 372
Location: Charleroi, Belgium

PostPosted: Wed Oct 31, 2012 7:29 am    Post subject: Reply with quote

#1. Chain[4] : 3r6c3=(3-1)r6c5=HP(16-4)rc56=4r4c1 :=> +3r3c1
#2. Chain[1] : Pointing : 7r2c2=7r3c2 :=> -7r79c2
#3. Chain[3] : XY Wing : (2=4)r4c1-(4=82)r69c2 :=> +2r4c1
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Wed Oct 31, 2012 7:35 pm    Post subject: Reply with quote

Or, using the UR (AUR?) 28, r14c79:-

3r4c7 = 1r4c79 - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3

(Yes, I know I should stick the letters UR or AUR in there somewhere, but I haven't yet quite figured that out.)

This exposes the same 24, 48, 28 XY-wing, which solves the puzzle.
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JC Van Hay



Joined: 13 Jun 2010
Posts: 372
Location: Charleroi, Belgium

PostPosted: Wed Oct 31, 2012 8:34 pm    Post subject: Reply with quote

ffred wrote:
Or, using the UR (AUR?) 28, r14c79:-

3r4c7 = 1r4c79 - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3

(Yes, I know I should stick the letters UR or AUR in there somewhere, but I haven't yet quite figured that out.) ...

I am not a specialist of notations, but for me, your notation is quite clear.
If you want to make a reference to the UR inside the "Eureka notation", you could write, for example :
    UR(28)r14c79 = 3r4c7 = 1r4c79 - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3
    or
    UR(28)r14c79[3r4c7 = 1r4c79] - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3
where UR stands for Unresolvable Rectangle , at least one of a,b,c, ... is true while writing a=b=c=... and a derived SIS is written inside the brackets as a result of the UR.
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ronk



Joined: 07 May 2006
Posts: 397

PostPosted: Wed Oct 31, 2012 10:59 pm    Post subject: Reply with quote

ffred wrote:
Or, using the UR (AUR?) 28, r14c79:-

3r4c7 = 1r4c79 - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3

(Yes, I know I should stick the letters UR or AUR in there somewhere, but I haven't yet quite figured that out.)

If you don't mind brevity, the below should be adequate when using one strong link for internal DP busters.

3r4c7 =AUR= 1r4c79 - r6c89 = (1 - 3)r6c5 = r6c3; r4c1 <> 3

The "=AUR=" indicates a strong link due to a (surprise) AUR. Very Happy
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daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Thu Nov 01, 2012 6:02 pm    Post subject: Reply with quote

Code:
 A discontinuous loop that produces eliminations in [c1] and [b7].
 +--------------------------------------------------------------------------------+
 |  5       469     1       |  346     7       3469    |  28      69      28      |
 |  8       24679   2469    |  2456    12569   1469    |  157     3       157     |
 |  237     2679    2369    |  2568    125689  1689    |  157     69      4       |
 |--------------------------+--------------------------+--------------------------|
 |  234     5       7       |  9       1368    1468    |  1238    128     128     |
 |  6       1       238     |  578     358     78      |  23578   4       9       |
 |  9       48      348     |  4578    1358    2       |  6       1578    1578    |
 |--------------------------+--------------------------+--------------------------|
 |  247     246789  245689  |  1       2689    6789    |  24578   2578    3       |
 |  1247    3       24689   |  2678    2689    5       |  12478   1278    1278    |
 |  127     278     258     |  2378    4       378     |  9       12578   6       |
 +--------------------------------------------------------------------------------+
 # 157 eliminations remain

 (4+127=127+8)r78c1,r9c12 - (8=4)r6c2 - r4c1 = (4)r78c1  =>  r4c1,r7c23,r8c3<>4

 ste

What also caught my attention was the number of Hidden Singles in the ste.
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Sun Nov 04, 2012 10:13 pm    Post subject: Reply with quote

Thanks JC & Ronk. Both seem good, but since I'm all for brevity I'll probably go for Ronk's, which matches what I do myself when I'm writing down moves: I write a subscript UR under the =.

Daj. My young grandson startled us all one day by saying solemnly [Grandpa], "That's seriously clever" - it seems apposite to echo that back to you.
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