The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.8.|...|..7|
 |6.7|45.|..3|
 |...|6..|8..|
 |---+---+---|
 |..8|..9|3..|
 |1..|.3.|..9|
 |..3|2..|5..|
 |---+---+---|
 |..9|..2|...|
 |7..|.16|2.5|
 |5..|...|.9.|
 *-----------*


Play/Print this puzzle online

[pjb]

Code: Select all

d49-1    8       25     | 13    a29     13     | 469    2456   7     
 6       129     7      | 4      5      8      | 19     12     3     
 3      c1249    125    | 6     b29     7      | 8      1245   124   
------------------------+----------------------+---------------------
e24      5       8      | 17     467    9      | 3      12467  1246   
 1       2467    26     | 8      3      5      | 46     2467   9     
 49      4679    3      | 2      467    14     | 5      1467   8     
------------------------+----------------------+---------------------
 8       16      9      | 5      47     2      | 1467   3      146   
 7       3       4      | 9      1      6      | 2      8      5     
 5       126     126    | 37     8      34     | 1467   9      146

(2=9)r1c5 - r3c5 = (9-4)r3c2 = r1c1 - (4=2)r4c1 => -2 r1c1; stte

Phil

[SteveG48]

Code: Select all

 *---------------------------------------------------------------------*
 |d249    8     e25     | 13     29     13     | 469    456-2   7      |
 | 6     e129    7      | 4      5      8      | 19     1-2     3      |
 | 3     e149-2 e15-2   | 6      9-2    7      | 8      145-2 af124    |
 *----------------------+----------------------+-----------------------|
 |c24     5      8      | 17     467    9      | 3      12467  b1246   |
 | 1      2467   26     | 8      3      5      | 46     2467    9      |
 | 49     4679   3      | 2      467    14     | 5      1467    8      |
 *----------------------+----------------------+-----------------------|
 | 8      16     9      | 5      47     2      | 1467   3       146    |
 | 7      3      4      | 9      1      6      | 2      8       5      |
 | 5      126    126    | 37     8      34     | 1467   9       146    |
 *---------------------------------------------------------------------*


(2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9 => -2 r12c8,r3c2358 ; stte

[pjb]

Steve

Apologies if I'm missing something here, but this seems to me to be a discontinuous loop allowing you to assign 2 to r3c9 (which solves puzzle). I don't get all the other eliminations, though. Can you please explain further?

Phil

[daj95376]

(2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9 => -2 r12c8,r3c2358 ; stte

The one elimination that you forgot to include is the one that should have been your main focal point ... and your sole elimination.

Code: Select all

(2)r3c9 =    r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9

          (2)r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9 - (2)r4c9


_

[Leren]

Code: Select all

*--------------------------------------------------------------*
|d49-2  8     25     | 13   a29    13     | 469   2456  7      |
| 6     129   7      | 4     5     8      | 19    12    3      |
| 3    c1249  125    | 6    b29    7      | 8     1245  124    |
|--------------------+--------------------+--------------------|
| 24    5     8      | 17    467   9      | 3     12467 1246   |
| 1     2467  26     | 8     3     5      | 46    2467  9      |
| 49    4679  3      | 2     467   14     | 5     1467  8      |
|--------------------+--------------------+--------------------|
| 8     16    9      | 5     47    2      | 1467  3     146    |
| 7     3     4      | 9     1     6      | 2     8     5      |
| 5     126   126    | 37    8     34     | 1467  9     146    |
*--------------------------------------------------------------*

H2 Wing: (2=9) r1c5 - r3c5 = (9-4) r3c2 = (4) r1c1 => - 2 r1c1; stte

Leren

[SteveG48]

Steve

Apologies if I'm missing something here, but this seems to me to be a discontinuous loop allowing you to assign 2 to r3c9 (which solves puzzle). I don't get all the other eliminations, though. Can you please explain further?

Phil

Basically the same thing, Phil. I could have written what I did write, or -14 r2c9, or r2c9=2. They're all equivalent, eliminating 2 everywhere in box 3 and row 3 except r3c9.

[SteveG48]

(2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9 => -2 r12c8,r3c2358 ; stte

The one elimination that you forgot to include is the one that should have been your main focal point ... and your sole elimination.

Code: Select all

(2)r3c9 =    r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9

          (2)r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 - (14=2)r3c9 - (2)r4c9


_

I'm not sure where you're coming from Danny- though I suspect I'm about to learn something. I wrote a chain that begins and ends on a strong link, which seems to be the preferred technique. I did forget one elimination. You wrote a very similar chain, though one term shorter, that begins and ends on a weak link and establishes the elimination that I missed and solves the puzzle (as mine did). Other than the shorter chain, is there a reason why r4c9 should have been my main focus?

Note that I could have written (2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 => -14r3c9, which is one term shorter. I elected not to go back and change it; perhaps I should have. I think this chain also gives me -2 r3c23, correct?

[daj95376]

I'm not sure where you're coming from Danny- though I suspect I'm about to learn something. I wrote a chain that begins and ends on a strong link, which seems to be the preferred technique. I did forget one elimination. You wrote a very similar chain, though one term shorter, that begins and ends on a weak link and establishes the elimination that I missed and solves the puzzle (as mine did). Other than the shorter chain, is there a reason why r4c9 should have been my main focus?

Note that I could have written (2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 => -14r3c9, which is one term shorter. I elected not to go back and change it; perhaps I should have. I think this chain also gives me -2 r3c23, correct?

My chain has the same number of terms as yours. Unfortunately, my point was obscure. Sorry!

You had a discontinuous loop that started with a strong link and ended with a strong link. The result is an assignment.

I was trying to show that your discontinuous loop could have started with a weak link and ended with a weak link. Then, an elimination in <2> would be more apparent.

In retrospect, I realize that I should have suggested that you drop the first SL.

_

[SteveG48]

Thanks, Danny.

Am I correct in writing:

(2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 => -14r3c9, -2 r3c23 ?

Deal with the 14 pair is a little more complicated than the usual form, but I think this is right.

[daj95376]

Thanks, Danny.

Am I correct in writing:

(2)r3c9 = r4c9 - r4c1 = r1c1 - (2=5914)b1p3589 => -14r3c9, -2 r3c23 ?

Deal with the 14 pair is a little more complicated than the usual form, but I think this is right.

I understand your logic, and it appears technically correct to me ... but I'd actually credit the eliminations on <2> to the embedded chain:

(2)r3c9 = r4c9 - r4c1 = (2)r1c1 => -2 r1c8,r3c23

_