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[ArkieTech]

Code: Select all

 *-----------*
 |..7|2..|..5|
 |.3.|..4|.9.|
 |4.8|9..|...|
 |---+---+---|
 |9.3|..5|..1|
 |...|...|...|
 |2..|8..|5.4|
 |---+---+---|
 |...|..8|3.9|
 |.1.|4..|.7.|
 |8..|..6|4..|
 *-----------*


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[Leren]

Code: Select all

*--------------------------------------------------------------------------------*
|a16      9       7        | 2       1368    13       | 168     4       5        |
|a156     3       1256     | 1567    15678   4        | 12678   9       678      |
| 4      d26-5    8        | 9       1567    17       | 1267    236     367      |
|--------------------------+--------------------------+--------------------------|
| 9       4678    3        | 67      2467    5        | 267     268     1        |
| 1567    45678   1456     | 1367    123467  1237     | 9       2368    367      |
| 2       67      16       | 8       13679   1379     | 5       36      4        |
|--------------------------+--------------------------+--------------------------|
|b567    c24567   2456     |b157    b1257    8        | 3      b15      9        |
| 3       1       259      | 4       259     29       | 68      7       68       |
| 8       57      59       | 1357    13579   6        | 4       15      2        |
*--------------------------------------------------------------------------------*

(5=6) r12c1 - (6=2) r7c1458 - r7c2 = (2) r3c2 => - 5 r3c2; stte

Leren

[SteveG48]

Code: Select all

 *-----------------------------------------------------------------------------*
 |d16      9       7       | 2       1368    13      | 168     4       5       |
 |d156     3      b1256    | 1567    15678   4       | 12678   9       678     |
 | 4      a26-5    8       | 9       1567    17      | 1267    236     367     |
 *-------------------------+-------------------------+-------------------------|
 | 9       4678    3       | 67      2467    5       | 267     268     1       |
 | 1567    45678   1456    | 1367    123467  1237    | 9       2368    367     |
 | 2       67      16      | 8       13679   1379    | 5       36      4       |
 *-------------------------+-------------------------+-------------------------|
 |c567     24567   2456    | 157     1257    8       | 3       15      9       |
 | 3       1      c259     | 4       259     29      | 68      7       68      |
 | 8      c57     c59      | 1357    13579   6       | 4       15      2       |
 *-----------------------------------------------------------------------------*


2r3c2 = r2c3 - (2=5679)b7p1689 - (6=15)r12c1 => -5 r3c2 ; stte

[pjb]

Code: Select all

a16      9       7      | 2      1368   13     | 168    4      5     
a156     3       1256   | 1567   15678  4      | 12678  9      678   
 4       26-5    8      | 9      1567   17     | 1267   236    367   
------------------------+----------------------+---------------------
 9      c4678    3      | 67     2467   5      | 267    268    1     
 1567   c45678   1456   | 1367   123467 1237   | 9      2368   367   
 2      c67      16     | 8      13679  1379   | 5      36     4     
------------------------+----------------------+---------------------
b567    c24567   2456   |b157   b1257   8      | 3     b15     9     
 3       1       259    | 4      259    29     | 68     7      68     
 8      c57      59     | 1357   13579  6      | 4      15     2     


(5=6)r12c1 - (6=2)r7c1458 - (2=5)r45679c2 => -5 r3c2; stte

Phil

[Marty R.]

Code: Select all

+-----------------+------------------+----------------+
| 16   9     7    | 2    1368   13   | 168   4    5   |
| 156  3     1256 | 1567 15678  4    | 12678 9    678 |
| 4    256   8    | 9    1567   17   | 1267  236  367 |
+-----------------+------------------+----------------+
| 9    4678  3    | 67   2467   5    | 267   268  1   |
| 1567 45678 1456 | 1367 123467 1237 | 9     2368 367 |
| 2    67    16   | 8    13679  1379 | 5     36   4   |
+-----------------+------------------+----------------+
| 567  24567 2456 | 157  1257   8    | 3     15   9   |
| 3    1     259  | 4    259    29   | 68    7    68  |
| 8    57    59   | 1357 13579  6    | 4     15   2   |
+-----------------+------------------+----------------+


Play this puzzle online at the Daily Sudoku site

M-Wing (59): (5=9)r9c3-r9c5=(9-5)r8c5=5r8c3=> -5r25c3,b7p1238

[Leren]

Maty R wrote :M-Wing (59): (5=9)r9c3-r9c5=(9-5)r8c5=5r8c3=> -5r25c3,b7p1238

Hi Marty. The part of your chain I marked in red looks a bit dodgy. There are 3 9's in Column 5.

Leren

[Leren]

pjb wrote: (5=6)r12c1 - (6=2)r7c1458 - (2=5)r45679c2 => -5 r3c2

Hi Phil, there is a typo in your PM - you've marked the 6 as the elimination instead of the 5.

Also, that was the first way I saw the move. Then I remembered some advice from Danny Jones, who said that when an ALS occupies all but one of the unsolved cells in it's house there is an alternative that uses fewer cells - in this case the two 2's in Column 2.

BTW, Danny has been conspicuous by his absence for a long time - does anyone know something I don't ?

Leren

[Marty R.]

It's been conspicuous to me as well. Looks like his most recent post was August 23.

[JC Van Hay]

Code: Select all

+------------------------+--------------------+------------------+
| 16    9         7      | 2     1368    13   | 168    4     5   |
| 156   3         126-5  | 1567  15678   4    | 12678  9     678 |
| 4     6(25)     8      | 9     167(5)  17   | 1267   236   367 |
+------------------------+--------------------+------------------+
| 9     4678      3      | 67    2467    5    | 267    268   1   |
| 1567  45678     146-5  | 1367  123467  1237 | 9      2368  367 |
| 2     67        16     | 8     13679   1379 | 5      36    4   |
+------------------------+--------------------+------------------+
| 67-5  467-5(2)  246-5  | 157   1257    8    | 3      15    9   |
| 3     1         (59-2) | 4     29(5)   29   | 68     7     68  |
| 8     7-5       (59)   | 1357  13579   6    | 4      15    2   |
+------------------------+--------------------+------------------+


L2-Wing or "Extended" Skyscraper : 2r7c2=(2-5)r3c2=5r3c5-5r8c5=5r8c3 => +NP(59)r89c3; stte

[Marty R.]

Maty R wrote :M-Wing (59): (5=9)r9c3-r9c5=(9-5)r8c5=5r8c3=> -5r25c3,b7p1238

Hi Marty. The part of your chain I marked in red looks a bit dodgy. There are 3 9's in Column 5.

Leren

OK, thanks for keeping me honest. There is no M-Wing there, but there would've been had there not been a 9 in r8c6. As to "There are 3 9's in Column 5.", I don't understand the relevance of column 5.

[Leren]

Marty R wrote : I don't understand the relevance of column 5

The M Wing move would have been valid if had only been two 9's in Columns 5 but there was a third one in r6c5. If that had not been there this part of your chain "r9c5=(9-5)r8c5" would have been OK.

Leren

[Marty R.]

Ok, thanks. It took me a while but now I get it.

[Sudtyro2]

...Then I remembered some advice from Danny Jones, who said that when an ALS occupies all but one of the unsolved cells in it's house there is an alternative that uses fewer cells - in this case the two 2's in Column 2.Leren

Hi Leren,
Need a little help on Danny's advice. If one removes any one unsolved cell in a house, you get a resulting ALS. Didn't realize that there was always a smaller alternative. Can you supply a link?

And yes, I've also missed Danny's feedback since late August.

SteveC

[Leren]

Sudtyro2 wrote : Need a little help on Danny's advice. If one removes any one unsolved cell in a house, you get a resulting ALS. Didn't realize that there was always a smaller alternative. Can you supply a link?

I don't know whether there is always a smaller alternative, but there often is.

Have a look at these two posts;

http://forum.enjoysudoku.com/post244116.html?hilit=als#p244116

http://forum.enjoysudoku.com/post236113.html?hilit=ALS%20leren#p236113

Leren