September 3, 2017

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September 3, 2017

Postby ArkieTech » Sat Sep 02, 2017 10:56 pm

Code: Select all
  *-----------*
 |.5.|3.7|..1|
 |...|1.6|...|
 |.1.|.5.|3..|
 |---+---+---|
 |62.|...|.4.|
 |.95|...|81.|
 |.4.|...|.76|
 |---+---+---|
 |..4|.8.|.3.|
 |...|9.5|...|
 |8..|4.3|.2.|
 *-----------*


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Re: September 3, 2017

Postby Leren » Sat Sep 02, 2017 11:09 pm

Code: Select all
*------------------------------------------*
| 49   5  2   | 3    49   7   | 6   8  1   |
| 3479 8  37  | 1    249  6   | 27  5  247 |
| 47   1  6   | 28   5    248 | 3   9  247 |
|-------------+---------------+------------|
| 6    2  378 | 578  1-3  189 |a59  4 a359 |
| 37   9  5   | 267  2346 24  | 8   1  23  |
| 1    4  38  | 258 c23   289 |b259 7  6   |
|-------------+---------------+------------|
| 5    67 4   | 26   8    12  | 179 3  79  |
| 2    3  1   | 9    7    5   | 4   6  8   |
| 8    67 9   | 4    16   3   | 157 2  57  |
*------------------------------------------*

(3=59) r4c79 - (59=2) r6c7 - (2=3) r6c5 => - 3 r4c5; stte

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Re: September 3, 2017

Postby SteveG48 » Sat Sep 02, 2017 11:45 pm

Code: Select all
 *-----------------------------------------------------------*
 | 49    5     2     | 3     49    7     | 6     8     1     |
 | 3479  8     37    | 1     249   6     | 27    5     247   |
 | 47    1     6     | 28    5     248   | 3     9     247   |
 *-------------------+-------------------+-------------------|
 | 6     2     378   | 578  c13    189   | 59    4     359   |
 | 7-3   9     5     | 267  d2346 d24    | 8     1    d23    |
 | 1     4    a38    | 258  b23    289   | 259   7     6     |
 *-------------------+-------------------+-------------------|
 | 5     67    4     | 26    8     12    | 179   3     79    |
 | 2     3     1     | 9     7     5     | 4     6     8     |
 | 8     67    9     | 4    c16    3     | 157   2     57    |
 *-----------------------------------------------------------*


3r6c3 = r6c5 - (3=16)r49c5 - (6=234)r5c569 => -3 r5c1 ; stte
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Re: September 3, 2017

Postby eleven » Sat Sep 02, 2017 11:51 pm

Code: Select all
 *------------------------------------------------------------*
 | #49     5    2     |  3    #49     7     |  6     8  1     |
 | #3479   8    37    |  1    #249    6     |  27    5  247   |
 | c47     1    6     |  28    5     a248   |  3     9  247   |
 |--------------------+---------------------+-----------------|
 |  6      2    378   |  578   13     189   |  59    4  359   |
 | b37     9    5     |  267   2346  b24    |  8     1 b23    |
 |  1      4    38    |  258   23     289   |  259   7  6     |
 |--------------------+---------------------+-----------------|
 |  5      67   4     |  26    8      12    |  179   3  79    |
 |  2      3    1     |  9     7      5     |  4     6  8     |
 |  8      67   9     |  4     16     3     |  157   2  57    |
 *------------------------------------------------------------*

UR 49r12c15: 4r3c1=r3c6
4r3c1=UR=r3c6-(4=7)r5c169-(7=4)r3c1 => 4r3c1, stte
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Re: September 3, 2017

Postby Marty R. » Sun Sep 03, 2017 12:12 am

Code: Select all
+-------------+--------------+-----------+
| 49   5  2   | 3   49   7   | 6   8 1   |
| 3479 8  37  | 1   249  6   | 27  5 247 |
| 47   1  6   | 28  5    248 | 3   9 247 |
+-------------+--------------+-----------+
| 6    2  378 | 578 13   189 | 59  4 359 |
| 37   9  5   | 267 2346 24  | 8   1 23  |
| 1    4  38  | 258 23   289 | 259 7 6   |
+-------------+--------------+-----------+
| 5    67 4   | 26  8    12  | 179 3 79  |
| 2    3  1   | 9   7    5   | 4   6 8   |
| 8    67 9   | 4   16   3   | 157 2 57  |
+-------------+--------------+-----------+

Play this puzzle online at the Daily Sudoku site



Same elimination as Leren
M-Wing (23) (3=2)r6c5-r6c7=(2-3)r5c9=3r4c9=> -3r4c5
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Re: September 3, 2017

Postby Marty R. » Sun Sep 03, 2017 4:07 am

eleven wrote:
Code: Select all
 *------------------------------------------------------------*
 | #49     5    2     |  3    #49     7     |  6     8  1     |
 | #3479   8    37    |  1    #249    6     |  27    5  247   |
 | c47     1    6     |  28    5     a248   |  3     9  247   |
 |--------------------+---------------------+-----------------|
 |  6      2    378   |  578   13     189   |  59    4  359   |
 | b37     9    5     |  267   2346  b24    |  8     1 b23    |
 |  1      4    38    |  258   23     289   |  259   7  6     |
 |--------------------+---------------------+-----------------|
 |  5      67   4     |  26    8      12    |  179   3  79    |
 |  2      3    1     |  9     7      5     |  4     6  8     |
 |  8      67   9     |  4     16     3     |  157   2  57    |
 *------------------------------------------------------------*

UR 49r12c15: 4r3c1=r3c6
4r3c1=UR=r3c6-(4=7)r5c169-(7=4)r3c1 => 4r3c1, stte


Help me understand the embedded UR. I can't make any sense of it. If it was removed we'd have 4r3c1=r3c6-(4=7)... So why is it there and what does it mean?
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Re: September 3, 2017

Postby eleven » Sun Sep 03, 2017 9:37 am

Hi Marty,

4r3c1 and 4r3c6 are the externals of the UR49r12c15 in the 2 boxes (if they are missing, the UR cells are left with 2 hidden pairs 49, a deadly pattern).

You probably would write it
DP 49r12c15 using externals:
4r3c1
4r3c6-(4=2)r5c6-(2=3)r5c9-(3=7)r5c1-(7=4)r3c1
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Re: September 3, 2017

Postby bat999 » Sun Sep 03, 2017 11:07 am

Code: Select all
.-----------------.----------------.----------------.
| a49    5    2   | 3    49    7   |  6    8   1    |
| b3479  8   b37  | 1    249   6   | b27   5   47-2 |
| a47    1    6   | 28   5     248 |  3    9   47-2 |
:-----------------+----------------+----------------:
|  6     2    378 | 578  13    189 |  59   4   359  |
| a37    9    5   | 267  2346  24  |  8    1  a23   |
|  1     4    38  | 258  23    289 |  59-2 7   6    |
:-----------------+----------------+----------------:
|  5     67   4   | 26   8     12  |  179  3   79   |
|  2     3    1   | 9    7     5   |  4    6   8    |
|  8     67   9   | 4    16    3   |  157  2   57   |
'-----------------'----------------'----------------'
(2=49)r135c1,r5c9 - (4|9=2)r2c137 => -2 r23c9,r6c7; stte
8-)
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Re: September 3, 2017

Postby Marty R. » Sun Sep 03, 2017 12:05 pm

eleven wrote:Hi Marty,

4r3c1 and 4r3c6 are the externals of the UR49r12c15 in the 2 boxes (if they are missing, the UR cells are left with 2 hidden pairs 49, a deadly pattern).

You probably would write it
DP 49r12c15 using externals:
4r3c1
4r3c6-(4=2)r5c6-(2=3)r5c9-(3=7)r5c1-(7=4)r3c1


I probably didn't make myself clear enough. I knew this was a UR using externals. What threw me off was the part of the notation in red. Usually when I see that embedded UR used it's part of the chain, but here I couldn't understand why it was there.

UR 49r12c15: 4r3c1=r3c6
4r3c1=UR=r3c6-(4=7)r5c169-(7=4)r3c1 => 4r3c1, stte
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Re: September 3, 2017

Postby pjb » Sun Sep 03, 2017 12:42 pm

Code: Select all
 49      5       2      | 3      49     7      | 6      8      1     
 3479    8       37     | 1      249    6      | 27     5      247   
b47      1       6      | 28     5      248    | 3      9     c247   
------------------------+----------------------+---------------------
 6       2       78-3   | 578    13     189    | 59     4     d359   
a37      9       5      | 267    2346   24     | 8      1      2-3     
 1       4       38     | 258    23     289    | 259    7      6     
------------------------+----------------------+---------------------
 5       67      4      | 26     8      12     | 179    3     d79     
 2       3       1      | 9      7      5      | 4      6      8     
 8       67      9      | 4      16     3      | 157    2     d57     

(3=7)r5c1 - r3c1 = r3c9 - (7=359)r479c9 => -3 r4c3, r5c9; stte

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Re: September 3, 2017

Postby eleven » Sun Sep 03, 2017 3:57 pm

Marty R. wrote:What threw me off was the part of the notation in red. Usually when I see that embedded UR used it's part of the chain, but here I couldn't understand why it was there.

UR 49r12c15: 4r3c1=r3c6
4r3c1=UR=r3c6-(4=7)r5c169-(7=4)r3c1 => 4r3c1, stte

The 2 externals of the UR provide a strong link between the 2 candidates 4r3c1 and 4r3c6 (at least one of them must be true, or - read from left to right - if 4 is not in r3c1, then in r3c6) and therefore can be used in an AIC, where a strong link is denoted as x=y. Since this is not obvious for the UR link, my way to write it is to first point out the link, and then to refer to it by =UR=.

Alternatively i have used
4r3c1=(UR49r12c15)4r3c6 ...

Other notations i saw are
(UR49r12c15)[4r3c1=4r4c6] ... (storm_norm22)
or
UR 49r12c15 using externals (4r3c1==r3c6)
4r3c1==r3c6 ... (Cenoman)

The logic is always the same.
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Re: September 3, 2017

Postby Cenoman » Sun Sep 03, 2017 8:44 pm

Code: Select all
 +--------------------+---------------------+-------------------+
 |  49     5    2     |  3     49     7     |  6     8    1     |
 | a3479*  8   a37*   |  1     249    6     |  2-7   5   d247   |
 | b47     1    6     |  28    5      248   |  3     9   d247   |
 +--------------------+---------------------+-------------------+
 |  6      2   a378*  |  578   13     189   |  59    4    359   |
 |ac37*    9    5     |  267   2346   24    |  8     1   d23    |
 |  1      4    38    |  258   23     289   |  259   7    6     |
 +--------------------+---------------------+-------------------+
 |  5      67   4     |  26    8      12    |  179   3    79    |
 |  2      3    1     |  9     7      5     |  4     6    8     |
 |  8      67   9     |  4     16     3     |  157   2    57    |
 +--------------------+---------------------+-------------------+

Finned XW(7) c13\r2b4 + rfr3c1
[XW(7)r2c1*=r5c1-r4c3=r2c3]
(7)r3c1 - (7=3)r5c1 - (3=7)r235c9
=> -2 r2c7; stte

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Re: September 3, 2017

Postby Cenoman » Sun Sep 03, 2017 9:00 pm

eleven wrote:UR 49r12c15 using externals (4r3c1==r3c6)
4r3c1==r3c6 ... (Cenoman)

Just one word. For me, the notation == means "derived strong link", i.e. a strong link to be used as a logic operator OR, not as an XOR (native strong link)
At least one term is TRUE, but all could be TRUE,
Such strong links can be derived from UR's and other DP's, or from krakens, or to shortcut long chains, and similar processes. Anyhow, the derivation process must always be explicit before use.
I am not the inventor of this notation. I borrowed it from other players (notably JC Van Hay).

Cenoman.
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