The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.1.|8..|7..|
 |.4.|..2|.56|
 |2..|6..|...|
 |---+---+---|
 |.6.|.3.|4.8|
 |...|481|...|
 |1.4|.9.|.7.|
 |---+---+---|
 |...|..7|..9|
 |37.|5..|.8.|
 |..6|..8|.3.|
 *-----------*
 

[Marty R.]

Code: Select all

+-------------+-------------+-------------+
| 6   1   59  | 8  45   349 | 7    2  34  |
| 78  4   3   | 19 17   2   | 189  5  6   |
| 2   59  78  | 6  1457 349 | 189  49 134 |
+-------------+-------------+-------------+
| 9   6   2   | 7  3    5   | 4    1  8   |
| 57  3   57  | 4  8    1   | 69   69 2   |
| 1   8   4   | 2  9    6   | 3    7  5   |
+-------------+-------------+-------------+
| 458 25  158 | 3  1246 7   | 1256 46 9   |
| 3   7   19  | 5  26   49  | 26   8  14  |
| 45  259 6   | 19 124  8   | 125  3  7   |
+-------------+-------------+-------------+


XY-Chain, r3c8=9-->r8c9=4; r13c9, r7c8<>4.

I'm going to take my first shot at notation; there's nothing simpler than this.

(4=9)r3c8-(9=5)r3c2-(5=9)r1c3-(9=1)r8c3-(1=4)r8c9-->r13c9, r7c8<>4.

Not sure if the above is correct but I also want to try a shortened version to see if it's valid.

9r3c8-9r3c2=9r1c3-(9=1)r8c3-(1=4)r8c9.

[tlanglet]

Code: Select all

+-------------+-------------+-------------+
| 6   1   59  | 8  45   349 | 7    2  34  |
| 78  4   3   | 19 17   2   | 189  5  6   |
| 2   59  78  | 6  1457 349 | 189  49 134 |
+-------------+-------------+-------------+
| 9   6   2   | 7  3    5   | 4    1  8   |
| 57  3   57  | 4  8    1   | 69   69 2   |
| 1   8   4   | 2  9    6   | 3    7  5   |
+-------------+-------------+-------------+
| 458 25  158 | 3  1246 7   | 1256 46 9   |
| 3   7   19  | 5  26   49  | 26   8  14  |
| 45  259 6   | 19 124  8   | 125  3  7   |
+-------------+-------------+-------------+


XY-Chain, r3c8=9-->r8c9=4; r13c9, r7c8<>4.

I'm going to take my first shot at notation; there's nothing simpler than this.

(4=9)r3c8-(9=5)r3c2-(5=9)r1c3-(9=1)r8c3-(1=4)r8c9-->r13c9, r7c8<>4.

Not sure if the above is correct but I also want to try a shortened version to see if it's valid.

9r3c8-9r3c2=9r1c3-(9=1)r8c3-(1=4)r8c9.

Marty,

Fantastic

To me, the first version is 100% A-1 OK.

The second version has one small detail missing. The beginning and end of an AIC act as pincers given that you start and end the chain with a strong link. You do not show the beginning 4 in r3c8 as part of the starting strong link. Thus your version becomes

(4=9)r3c8-9r3c2=9r1c3-(9=1)r8c3-(1=4)r8c9-->r8c9=4; r13c9, r7c8<>4

As always, others can offer better details about the whys and wherefores, but you nailed it.

[tlanglet]

My solution is not as simple as Marty's but it is what I found after a couple of interesting and fun steps that were useless.

(1=9)r8c3-r8c6=r9c4-(9=1=7=8)r2c451-r7c1=8r7c3 => -1r7c3

Edited to add second solution on 10/23 after finding I had posted it on Daily Sudoku which seems to be up and running.

9r9c2=9r3c2-(9=4)r3c8-r7c8=(4-1)r8c9=(1-9)r8c3=9r9c2 => 9r9c2

[ArkieTech]

Code: Select all

 *-----------------------------------------------------------*
 | 6     1     9=5   | 8    a45    349   | 7     2     34    |
 | 78    4     3     | 19    17    2     | 189   5     6     |
 | 2     59   c78    | 6    b1457  349   | 189   49    134   |
 |-------------------+-------------------+-------------------|
 | 9     6     2     | 7     3     5     | 4     1     8     |
 | 57    3    d57    | 4     8     1     | 69    69    2     |
 | 1     8     4     | 2     9     6     | 3     7     5     |
 |-------------------+-------------------+-------------------|
 | 458   25    158   | 3     1246  7     | 1256  46    9     |
 | 3     7     19    | 5     26    49    | 26    8     14    |
 | 45    259   6     | 19    124   8     | 125   3     7     |
 *-----------------------------------------------------------*
m-wing
(7=5)r5c3-r3c3=(5-7)r3c5=5r1c3 => -5r1c3; stte