The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|.9.|4..|
 |.46|...|.23|
 |..8|..7|...|
 |---+---+---|
 |...|..4|2..|
 |.95|.1.|...|
 |..3|.7.|8..|
 |---+---+---|
 |...|..3|...|
 |...|5..|..4|
 |...|8..|965|
 *-----------*


Play/Print this puzzle online

[Ngisa]

Code: Select all

+-------------------+---------------------+----------------+
| 35      35      7 |d26      9      e26  | 4     1      8 |
| 9       4       6 | 1       58      58  | 7     2      3 |
| 12      12      8 | 4       3       7   | 5     9      6 |
+-------------------+---------------------+----------------+
| 678     678     1 | 36      58      4   | 2     35     9 |
| 248     9       5 |c23      1       28  | 6    b34     7 |
| 246     26      3 | 9       7      f26-5| 8    a45     1 |
+-------------------+---------------------+----------------+
| 56      56      9 | 7       4       3   | 1     8      2 |
| 18      18      2 | 5       6       9   | 3     7      4 |
| 37      37      4 | 8       2       1   | 9     6      5 |
+-------------------+---------------------+----------------+


(5=4)r6c8 - (4=3)r5c8 -(3=2)r5c4 - (2=6)r1c4 - r1c6 = (6)r6c6 => - 5r6c6; stte

Clement

[SteveG48]

Code: Select all

 *--------------------------------------------------*
 | 35   35   7    | 26   9    26   | 4    1    8    |
 | 9    4    6    | 1    58   58   | 7    2    3    |
 | 12   12   8    | 4    3    7    | 5    9    6    |
 *----------------+----------------+----------------|
 | 678  678  1    | 36  a58   4    | 2    3-5  9    |
 | 248  9    5    |a23   1   a28   | 6   b34   7    |
 | 246  26   3    | 9    7    256  | 8   b45   1    |
 *----------------+----------------+----------------|
 | 56   56   9    | 7    4    3    | 1    8    2    |
 | 18   18   2    | 5    6    9    | 3    7    4    |
 | 37   37   4    | 8    2    1    | 9    6    5    |
 *--------------------------------------------------*


(5=238)b5p246 - (3=45)r56c8 => -5 r4c8 ; stte

[999_Springs]

can someone tell me what this move is called again, it's been forever, i think it's called a reverse UR? basically if you swap columns 1 and 2 and switch the 4 ur cells around you get another solution so the ur can't happen

Reverse UR 49r25c12 => -4r5c1 stte

first one of these i've spotted Luke get back on here i know you're a fan of this sort of thing

[Sudtyro2]

Code: Select all

+--------------+---------------+--------------+
| 35  35  7    | 26  9  b26    | 4   1   8    |
| 9   4   6    | 1   58  58    | 7   2   3    |
| 12  12  8    | 4   3   7     | 5   9   6    |
+--------------+---------------+--------------+
| 678 678 1    | 36  58  4     | 2   35  9    |
| 248 9   5    | 23* 1   8-2   | 6   34* 7    |
| 246 26  3    | 9   7  a25+6* | 8   45* 1    |
+--------------+---------------+--------------+
| 56  56  9    | 7   4   3     | 1   8   2    |
| 18  18  2    | 5   6   9     | 3   7   4    |
| 37  37  4    | 8   2   1     | 9   6   5    |
+--------------+---------------+--------------+

5-sector Almost Disjoint Subset(*)...
DS(2345) == 6r6c6 - (6=2)r1c6 => - 2r5c6; stte

SteveC

[eleven]

can someone tell me what this move is called again, it's been forever, i think it's called a reverse UR? basically if you swap columns 1 and 2 and switch the 4 ur cells around you get another solution so the ur can't happen

Reverse UR 49r25c12 => -4r5c1 stte

first one of these i've spotted Luke get back on here i know you're a fan of this sort of thing

You probably mean a reverse BUG, but you can't apply it here.

[SpAce]

5-sector Almost Disjoint Subset(*)...
DS(2345) == 6r6c6 - (6=2)r1c6 => - 2r5c6; stte

Beautiful!

[999_Springs]

can someone tell me what this move is called again, it's been forever, i think it's called a reverse UR? basically if you swap columns 1 and 2 and switch the 4 ur cells around you get another solution so the ur can't happen

Reverse UR 49r25c12 => -4r5c1 stte

first one of these i've spotted Luke get back on here i know you're a fan of this sort of thing

You probably mean a reverse BUG, but you can't apply it here.

I looked through the reverse bug thread and am pretty sure it's not that but something similar. If you look at the first example in that thread with r1c3-1 the logic behind it goes like this

- all the 18 cells that will have 1 and 2 in the solution form an unavoidable set
- if any subset of those cells form an unavoidable set then its complement must also
- since the rest of the puzzle has no solved 1s or 2s in it then you can't have 1r1c3

whereas in the given puzzle it goes like this
- all of the 18 cells in columns 1 and 2 form an unavoidable set (it isn't about where the 4s and 9s are elsewhere, so not a reverse bug)
- if any subset of those cells form an unavoidable set then its complement must also
- since the rest of columns 1 and 2 are unsolved then you can't have 4r5c1

if it were the case that we had filled in some of the other cells in columns 1 and 2 we would have to look back at the original puzzle to see if they were clues as originally given, but we don't have any here.

I'm sure we can play this move as the remaining 14 cells in columns 1 and 2 are all unsolved and would form an unavoidable set if r5c1=4 (is it a bug lite or something?)

I miss the old days of this forum :/

[eleven]

Oh yes, i forgot about that, it's a Reverse BUG-Lite.
You already explained, how it works.

Hint: there is a sticked thread "Collection of solving techniques" at top of the "Advanced solving techniques" forum.

[999_Springs]

got it, thanks

[rjamil]

Code: Select all

....9.4...46....23..8..7........42...95.1......3.7.8.......3......5....4...8..965
 +-----------+----------------+----------+
 | 35  35  7 | 26   9    26   | 4 1    8 |
 | 9   4   6 | 1    58   58   | 7 2    3 |
 | 12  12  8 | 4    3    7    | 5 9    6 |
 +-----------+----------------+----------+
 | 678 678 1 | 6-3  (58) 4    | 2 (35) 9 |
 | 248 9   5 | (23) 1    (28) | 6 4-3  7 |
 | 246 26  3 | 9    7    256  | 8 45   1 |
 +-----------+----------------+----------+
 | 56  56  9 | 7    4    3    | 1 8    2 |
 | 18  18  2 | 5    6    9    | 3 7    4 |
 | 37  37  4 | 8    2    1    | 9 6    5 |
 +-----------+----------------+----------+

WXYZ-Wings: 2358 @ r4c58, r5c46 => -3 @ r4c4, r5c8; stte

R. Jamil

[pjb]

Code: Select all

 35      35      7      | 26     9      26     | 4      1      8     
 9       4       6      | 1      58     58     | 7      2      3     
 12      12      8      | 4      3      7      | 5      9      6     
------------------------+----------------------+---------------------
 678     678     1      |d36    b58     4      | 2     a35     9     
 248     9       5      | 23     1      28     | 6      34     7     
 246     26      3      | 9      7     c256    | 8      45     1     
------------------------+----------------------+---------------------
 56      56      9      | 7      4      3      | 1      8      2     
 18      18      2      | 5      6      9      | 3      7      4     
 37      37      4      | 8      2      1      | 9      6      5     


(3=5)r4c8 - r4c5 = (5-6)r6c6 = r4c4 => -3 r4c4; stte

Phil