The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|..8|5..|
 |9..|.45|28.|
 |...|...|.37|
 |---+---+---|
 |.73|85.|.6.|
 |...|...|...|
 |.2.|.74|35.|
 |---+---+---|
 |49.|...|...|
 |.52|36.|..9|
 |..1|4..|...|
 *-----------*


Play/Print this puzzle online

[Leren]

Code: Select all

*--------------------------------------------------------------*
| 267   146  c467    | 1279  3     8      | 5     149   16-4   |
| 9     3    c67     | 17    4     5      | 2     8     16     |
| 258   148   458    | 129   129   6      | 149   3     7      |
|--------------------+--------------------+--------------------|
| 1     7     3      | 8     5    a29     | 49    6    a24     |
| 568   468   45689  | 1269  129   3      | 179   179   128    |
| 68    2     689    | 169   7     4      | 3     5     18     |
|--------------------+--------------------+--------------------|
| 4     9    c678    | 5    b28   b127    | 1678  127   3      |
| 78    5     2      | 3     6    b17     | 1478  147   9      |
| 3     68    1      | 4     289  b279    | 678   27    5      |
*--------------------------------------------------------------*

ALS XY Wing: (4=9) r4c69 - (9=8) r7c56, r8c6, r9c6 - (8=4) r127c3 => - 4 r1c9; stte

Leren

[SteveG48]

Code: Select all

 *--------------------------------------------------------------------*
 | 267    146   a467    |d1279   3      8      | 5      149    16-4   |
 | 9      3     a67     | 17     4      5      | 2      8      16     |
 | 258    148    458    |d129   c129    6      | 149    3      7      |
 *----------------------+----------------------+----------------------|
 | 1      7      3      | 8      5     f29     | 49     6     g24     |
 | 568    468    45689  |e1269 ce129    3      | 179    179    128    |
 | 68     2      689    | 169    7      4      | 3      5      18     |
 *----------------------+----------------------+----------------------|
 | 4      9     a678    | 5     b28     127    | 1678   127    3      |
 | 78     5      2      | 3      6      17     | 1478   147    9      |
 | 3      68     1      | 4      289    279    | 678    27     5      |
 *--------------------------------------------------------------------*


(4=678)r127c3 - (8=2)r7c5 - r35c5* = r13c4 - r5c4*5 = r4c6 - (2=4)r4c9 => -4 r1c9 ; stte

[pjb]

Code: Select all

 267     146    f467    | 1279   3      8      | 5      149   c146   
 9       3      e67     | 17     4      5      | 2      8     d16     
 258     148     458    | 129    129    6      | 149    3      7     
------------------------+----------------------+---------------------
 1       7       3      | 8      5     a29     | 49     6     b24     
 568     468     45689  | 1269   19-2   3      | 179    179    128   
 68      2       689    | 169    7      4      | 3      5      18     
------------------------+----------------------+---------------------
 4       9      g678    | 5     h28     17-2   | 1678   127    3     
 78      5       2      | 3      6      17     | 1478   147    9     
 3       68      1      | 4      289    79-2   | 678    27     5     


(2)r4c6 = (2-4)r4c9 = (4-6)r1c9* = r2c9 - (6=7)r2c3^ - (47=6)r1c3* - (67=8)r7c3^ - (8=2)r7c5 => -2 r5c5, r79c6; stte

Phil

[David P Bird]

(4=678)r127c3 - (8=2)r7c5 - r35c5* = r13c4 - r5c4*5 = r4c6 - (2=4)r4c9 => -4 r1c9 ; stte

Steve please work though your chain again and check that all your links are valid for all possible distributions of the link digit in the two connected terms.
DPB

[SteveG48]

Code: Select all

 *--------------------------------------------------------------------*
 | 267    146   a467    |d1279   3      8      | 5      149    16-4   |
 | 9      3     a67     | 17     4      5      | 2      8      16     |
 | 258    148    458    |d129   c129    6      | 149    3      7      |
 *----------------------+----------------------+----------------------|
 | 1      7      3      | 8      5     f29     | 49     6     g24     |
 | 568    468    45689  |e1269 ce129    3      | 179    179    128    |
 | 68     2      689    | 169    7      4      | 3      5      18     |
 *----------------------+----------------------+----------------------|
 | 4      9     a678    | 5     b28     127    | 1678   127    3      |
 | 78     5      2      | 3      6      17     | 1478   147    9      |
 | 3      68     1      | 4      289    279    | 678    27     5      |
 *--------------------------------------------------------------------*


(4=678)r127c3 - (8=2)r7c5 - r35c5* = r13c4 - r5c4*5 = r4c6 - (2=4)r4c9 => -4 r1c9 ; stte

Hi, David. As usual when using star notation and networking, I'm concerned about the notation, but I don't see a problem with the links.
Going through it one step at a time:


If r1c3 is not a 4, then the set r127c3 is locked with r7c3 being an 8.
Then r7c5 is a 2, and there are no other 2's in c5. In particular, r35c5 has no 2's.
Then either r1 or r3 c4 is a 2, and r5c4 is not.
The link from here to r4c6 would be invalid except we already know that r5c5 is not a 2. So r4c6 is a 2.
Then r4c9 must be a 4.

Are you asking for better notation or have I made a logical error? For notation I might prefer:

(4=678)r127c3 - (8=2)r7c5 - r35c5* = r13c4 - [r5c4|*r5c5] = r4c6 - (2=4)r4c9 .

Hmm. I can see it doesn't read backwards through the bracketed term. Lemme think a bit.....

[bat999]

Code: Select all

.------------------.------------------.------------------.
| 267  146  a467   | 1279   3     8   | 5     149   16-4 |
| 9    3    a67    | 17     4     5   | 2     8     16   |
| 258  148   458   | 129    129   6   | 149   3     7    |
:------------------+------------------+------------------:
| 1    7     3     | 8      5    d29  | 49    6    e24   |
| 568  468   45689 | 1269   129   3   | 179   179   128  |
| 68   2     689   | 169    7     4   | 3     5     18   |
:------------------+------------------+------------------:
| 4    9    a678   | 5     b28   c127 | 1678  127   3    |
| 78   5     2     | 3      6     17  | 1478  147   9    |
| 3    68    1     | 4      289  c279 | 678   27    5    |
'------------------'------------------'------------------'

(4=8)r127c3 - (8=2)r7c5 - r79c6 = r4c6 - (2=4)r4c9 => -4 r1c9; stte

[David P Bird]

Sorry Steve, I misread your almost naked triple in c3 and checked the wrong cells in the grid, so apologies.

If your personal aim is to find the solution as quickly as possible and are happy to use memory chains then I guess your solution is OK. But I think you should be aiming higher than that and trying to find a more 'elegant' linear chain solution.

As you have discovered, tying to read memory chains in the reverse direction requires fortune foretelling abilities!

DPB
.

[Marty R.]

tying to read memory chains in the reverse direction requires fortune foretelling abilities!

Speaking for myself only, they ain't so easy reading forward either.

[SteveG48]

Sorry Steve, I misread your almost naked triple in c3 and checked the wrong cells in the grid, so apologies.

If your personal aim is to find the solution as quickly as possible and are happy to use memory chains then I guess your solution is OK. But I think you should be aiming higher than that and trying to find a more 'elegant' linear chain solution.

As you have discovered, tying to read memory chains in the reverse direction requires fortune foretelling abilities!

DPB
.

Thanks, David. I'm never happy using memory chains, and try to find something better. When I can't, I do what I can. While the "one-step" focus of the dailies is not always conducive to elegance, it has at least been a good learning tool for a relative newcomer like myself.