The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |1.3|...|...|
 |6.7|..3|2.1|
 |.9.|16.|..7|
 |---+---+---|
 |...|2..|.1.|
 |..8|5.6|7..|
 |.6.|..7|...|
 |---+---+---|
 |4..|.28|.7.|
 |7.1|9..|4.2|
 |...|...|5.8|
 *-----------*


Play/Print this puzzle online

[SteveG48]

Code: Select all

 *-----------------------------------------------------------*
 | 1     245   3     | 478   4579  249   | 89   b4589  6     |
 | 6     45    7     | 48    459   3     | 2    b4589  1     |
 | 8     9     25    | 1     6     24    | 3    b45    7     |
 *-------------------+-------------------+-------------------|
 | 35    7     49    | 2     8     49    | 6     1     35    |
 |d239   1     8     | 5     49    6     | 7     239   349   |
 |c259   6    c249   | 3     1     7     | 89   b289   459   |
 *-------------------+-------------------+-------------------|
 | 4     35    59    | 6     2     8     | 1     7     39    |
 | 7     8     1     | 9     3     5     | 4     6     2     |
 | 9-2  a23    6     | 47    47    1     | 5    a39    8     |
 *-----------------------------------------------------------*


(2=39)r9c28 - (9=2458)r1236c8 - 2r6c13 = 2r5c1 => -2 r9c1 ; stte

[pjb]

Code: Select all

 1       245     3      | 478    4579   249    | 89     4589   6     
 6      d45      7      | 48     459    3      | 2      4589   1     
 8       9      c25     | 1      6     b24     | 3      45     7     
------------------------+----------------------+---------------------
 35      7       49     | 2      8     a49     | 6      1      35     
 239     1       8      | 5      49     6      | 7      239    349   
 259     6       249    | 3      1      7      | 89     289    459   
------------------------+----------------------+---------------------
 4       35      59     | 6      2      8      | 1      7      39     
 7       8       1      | 9      3      5      | 4      6      2     
 29      23      6      | 47     47     1      | 5      39     8     


(9=4)r4c6 => -4 r13c6
(9=4)r4c6 - (4=2)r3c6 - (2=4)r2c2,r3c3 => -4 r2c45 => r4c6 = 9; stte

Phil

[Marty R.]

Code: Select all

+-------------+--------------+-------------+
| 1   245 3   | 478 4579 249 | 89 4589 6   |
| 6   45  7   | 48  459  3   | 2  4589 1   |
| 8   9   25  | 1   6    24  | 3  45   7   |
+-------------+--------------+-------------+
| 35  7   49  | 2   8    49  | 6  1    35  |
| 239 1   8   | 5   49   6   | 7  239  349 |
| 259 6   249 | 3   1    7   | 89 289  459 |
+-------------+--------------+-------------+
| 4   35  59  | 6   2    8   | 1  7    39  |
| 7   8   1   | 9   3    5   | 4  6    2   |
| 29  23  6   | 47  47   1   | 5  39   8   |
+-------------+--------------+-------------+


Play this puzzle online at the Daily Sudoku site

(3=9)r9c8-(9=32)r9c12-r1c2=r3c3-(2=495)r467c3-(5=3)r7c2-=> -3r7c9

[JC Van Hay]

Code: Select all

+-----------------+----------------+-----------------+
| 1      245  3   | 478  4579  249 | 89  4589    6   |
| 6      45   7   | 48   459   3   | 2   4589    1   |
| 8      9    25  | 1    6     24  | 3   45      7   |
+-----------------+----------------+-----------------+
| 35     7    49  | 2    8     49  | 6   1       35  |
| 39(2)  1    8   | 5    49    6   | 7   9-3(2)  349 |
| 259    6    249 | 3    1     7   | 89  289     459 |
+-----------------+----------------+-----------------+
| 4      35   59  | 6    2     8   | 1   7       39  |
| 7      8    1   | 9    3     5   | 4   6       2   |
| (29)   23   6   | 47   47    1   | 5   (39)    8   |
+-----------------+----------------+-----------------+


{2r5c81, (29)r9c1, (93)r9c8} -> r5c8≠3; stte

[SteveG48]

Code: Select all

+-------------+--------------+-------------+
| 1   245 3   | 478 4579 249 | 89 4589 6   |
| 6   45  7   | 48  459  3   | 2  4589 1   |
| 8   9   25  | 1   6    24  | 3  45   7   |
+-------------+--------------+-------------+
| 35  7   49  | 2   8    49  | 6  1    35  |
| 239 1   8   | 5   49   6   | 7  239  349 |
| 259 6   249 | 3   1    7   | 89 289  459 |
+-------------+--------------+-------------+
| 4   35  59  | 6   2    8   | 1  7    39  |
| 7   8   1   | 9   3    5   | 4  6    2   |
| 29  23  6   | 47  47   1   | 5  39   8   |
+-------------+--------------+-------------+


Play this puzzle online at the Daily Sudoku site

(3=9)r9c8-(9=32)r9c12-r1c2=r3c3-(2=495)r467c3-(5=3)r7c2-=> -3r7c9

Marty, I don't follow the highlighted step. Eliminating 9 from r9c12 gives 2 in r9c1 and 3 in r9c2, so it doesn't weak link to the 2 in r1c2.

[SteveG48]

Code: Select all

 1       245     3      | 478    4579   249    | 89     4589   6     
 6      d45      7      | 48     459    3      | 2      4589   1     
 8       9      c25     | 1      6     b24     | 3      45     7     
------------------------+----------------------+---------------------
 35      7       49     | 2      8     a49     | 6      1      35     
 239     1       8      | 5      49     6      | 7      239    349   
 259     6       249    | 3      1      7      | 89     289    459   
------------------------+----------------------+---------------------
 4       35      59     | 6      2      8      | 1      7      39     
 7       8       1      | 9      3      5      | 4      6      2     
 29      23      6      | 47     47     1      | 5      39     8     


(9=4)r4c6 => -4 r13c6
(9=4)r4c6 - (4=2)r3c6 - (2=4)r2c2,r3c3 => -4 r2c45 => r4c6 = 9; stte

Phil

Phil, I understand that if r4c6 is a 9 than none of r13c6 or r2c45 can be a 4, but we still have candidate 4's at r1c45 in b2, so I don't understand the conclusion.

[Marty R.]

Marty, I don't follow the highlighted step. Eliminating 9 from r9c12 gives 2 in r9c1 and 3 in r9c2, so it doesn't weak link to the 2 in r1c2.

OK, thanks Steve, that was egregiously careless of me. (What would I do if you weren't around to keep me honest?)

[pjb]

Phil, I understand that if r4c6 is a 9 than none of r13c6 or r2c45 can be a 4, but we still have candidate 4's at r1c45 in b2, so I don't understand the conclusion.

Steve
This forces r1c45 to be the 47 naked pair which completes the UR. Therefore r4c6 must be 9.
Seasons greetings, Phil

[Sudtyro2]

{2r5c81, (29)r9c1, (93)r9c8} -> r5c8≠3; stte

JC, is this an alternate notation scheme for a simple AIC? I must have missed that class.

SteveC

[Marty R.]

This forces r1c45 to be the 47 naked pair which completes the UR. Therefore r4c6 must be 9.
Seasons greetings, Phil

I'm missing something, par for the course. If r1c45 is a 47 naked pair, doesn't that knock out 4s in c6, leaving r4c6=4?

[SteveG48]

Phil, I understand that if r4c6 is a 9 than none of r13c6 or r2c45 can be a 4, but we still have candidate 4's at r1c45 in b2, so I don't understand the conclusion.

Steve
This forces r1c45 to be the 47 naked pair which completes the UR. Therefore r4c6 must be 9.
Seasons greetings, Phil

Aha! Now I see it. Thanks, Phil.

[JC Van Hay]

{2r5c81, (29)r9c1, (93)r9c8} -> r5c8≠3; stte

JC, is this an alternate notation scheme for a simple AIC? I must have missed that class.

SteveC

SteveC,

The solutions of a set P of N constraints exclude a set X of candidates : P={C1, ..., CN} -> [set of derived constraints] -> -X.
To justify in details the exclusions, a player can read the set P either in "English", or in Nice Loop notation, or in Eureka notation, or in nrczt-chain/whip/braid notation, or in forbidding/exclusion matrix notation, or by drawing an SLG, ... in order to get the derived constraints.

JC

[ArkieTech]

The solutions of a set P of N constraints exclude a set X of candidates : P={C1, ..., CN} -> [set of derived constraints] -> -X.
To justify in details the exclusions, a player can read the set P either in "English", or in Nice Loop notation, or in Eureka notation, or in nrczt-chain/whip/braid notation, or in forbidding/exclusion matrix notation, or by drawing an SLG, ... in order to get the derived constraints.

I like

[eleven]

A notation i like, should
- give a hint for a manual player, how she could find a move herself
- show the complexity of a move

JC's does neither.
A known pattern is a known pattern, and an AIC or similar at least shows where to start and how the candidates/cells are connected to get to the conclusion.

In this notation both a simple move (as here) can be hidden and a complex network or base/cover move.
It might be useful to have a program, which finds such moves for harder puzzles, which then can be evaluated manually. But posting moves in this form is like giving readers a riddle (why is the elimination correct?).