The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |..8|7..|...|
 |...|..5|.4.|
 |.64|2.8|.75|
 |---+---+---|
 |4..|3..|.26|
 |..2|8.6|7..|
 |67.|..2|..9|
 |---+---+---|
 |82.|6.1|45.|
 |.1.|5..|...|
 |...|..3|8..|
 *-----------*


Play/Print this puzzle online

[Leren]

Code: Select all

*--------------------------------------------------------------------------------*
| 1235    35      8        | 7       4       9        | 1236    136     12       |
| 2379    39     c37       | 1       6       5        | 239     4       8        |
| 19      6       4        | 2       3       8        | 19      7       5        |
|--------------------------+--------------------------+--------------------------|
| 4       8      c15       | 3       9       7        | 15      2       6        |
|b359    b359     2        | 8       15      6        | 7      b13      4        |
| 6       7      c135      | 4       15      2        | 135     8       9        |
|--------------------------+--------------------------+--------------------------|
| 8       2       9        | 6       7       1        | 4       5       3        |
| 37      1      c367      | 5       8       4        | 2-6     9       27       |
| 57      4       57-6     | 9       2       3        | 8      a16      17       |
*--------------------------------------------------------------------------------*

als xy-wing: (6=1) r9c8 - (1=5) r5c128 - (5=6) r2468c3 => r8c7,r9c3 <> 6; stte

Leren

[Marty R.]

Code: Select all

+--------------+--------+-------------+
| 1235 35  8   | 7 4  9 | 1236 136 12 |
| 2379 39  37  | 1 6  5 | 239  4   8  |
| 19   6   4   | 2 3  8 | 19   7   5  |
+--------------+--------+-------------+
| 4    8   15  | 3 9  7 | 15   2   6  |
| 359  359 2   | 8 15 6 | 7    13  4  |
| 6    7   135 | 4 15 2 | 135  8   9  |
+--------------+--------+-------------+
| 8    2   9   | 6 7  1 | 4    5   3  |
| 37   1   367 | 5 8  4 | 26   9   27 |
| 57   4   567 | 9 2  3 | 8    16  17 |
+--------------+--------+-------------+


Play this puzzle online at the Daily Sudoku site

Some kind of chain.

(1=3)r5c8-r6c7=r6c3-(37=6)r28c3-(6=2)r8c7-(2=7)r8c9-(7=1)r9c9=>r9c8<>1

[daj95376]

Although this solution is from my solver, it does have two interesting "patterns" that may be of interest.

Grouped 2-String Kite b-cc-dd-e with both ends extended, or a 4-SIS L3-Wing (with an internal extension).

Code: Select all

 +--------------------------------------------------------------+
 |  1235  35    8     |  7     4     9     |  1236  136   12    |
 |  2379  39    37    |  1     6     5     |  239   4     8     |
 |  19    6     4     |  2     3     8     |  19    7     5     |
 |--------------------+--------------------+--------------------|
 |  4     8    d15    |  3     9     7     |  15    2     6     |
 | c359  c359   2     |  8    b15    6     |  7    a13    4     |
 |  6     7    d135   |  4     15    2     |  135   8     9     |
 |--------------------+--------------------+--------------------|
 |  8     2     9     |  6     7     1     |  4     5     3     |
 |  37    1     367   |  5     8     4     |  26    9     27    |
 |  57    4    e567   |  9     2     3     |  8    f16    17    |
 +--------------------------------------------------------------+
 # 42 eliminations remain

              |  grouped 2-String Kite  |

 (1)r5c8 = (1-5)r5c5 = r5c12 - r46c3 = (5-6)r9c3 = (6)r9c8  =>  r9c8<>1

 (X)a    = (X-Y)b                    = (Y-Z)c    = (Z)d     =>  a<>Z, d<>X
  | ------------------- L3-Wing ------------------- |


[eleven]

Nice.
I am nearer to the kite view (r5c5=5->r5c8=1 or r9c3=5->r9c1=7->r9c9=1), because i have even troubles to spot non grouped L3-wings.

[daj95376]

Nice.
I am nearer to the kite view (r5c5=5->r5c8=1 or r9c3=5->r9c1=7->r9c9=1), because i have even troubles to spot non grouped L3-wings.

I think it would be nice to have a Sudoku program whose graphics allowed you to select 1-k values and have the grouped and non-grouped strong links displayed in a different color for each value. Manually finding many of the 1-3-digit patterns would be so much easier!

(Yes, it's possible to manually accomplish something similar using Simple Sudoku, but I'd prefer assistance from the program when it comes to tracking strong links/inferences. )

Regards, Danny

[pjb]

Another twist on the above approaches using ER in box 4:

(1=7)r9c9 - (7=5) r9c1 - r9c3 = r46c3 - r5c12 = (5-1)r5c5 = (1)r5c8: r9c8 <> 1.

Phil

[DonM]

Nice.
I am nearer to the kite view (r5c5=5->r5c8=1 or r9c3=5->r9c1=7->r9c9=1), because i have even troubles to spot non grouped L3-wings.

I think it would be nice to have a Sudoku program whose graphics allowed you to select 1-k values and have the grouped and non-grouped strong links displayed in a different color for each value. Manually finding many of the 1-3-digit patterns would be so much easier!
Regards, Danny

If the program would be spitting out the 1-3 digit patterns (which I assume is occurring if the 1-k values grouped/ungrouped strong links are displayed color-coded by value) then it seems to me that one is not really manually finding them.

[Solgor]

I was able to solve this puzzle with two moves. There is a xy-wing in R1C9(12) R9C7(26)R9C8(16). Using this xy-wing eliminates the 2 in R8C9 making the 7 the correct choice for that cell. Then you can eliminate six lone numbers.

The second move is a remote pair (kite?) in R1C1(15)R3C1(19)R1C8(13) R1C8(13)R5C8(13). Using the kite eliminates the 1 from R3C7. The rest of the grid contains only 20 lone numbers.

Did I get lucky on this one or did I use the correct strategy?

[Marty R.]

I was able to solve this puzzle with two moves. There is a xy-wing in R1C9(12) R9C7(26)R9C8(16). Using this xy-wing eliminates the 2 in R8C9 making the 7 the correct choice for that cell. Then you can eliminate six lone numbers.

What you seem to be describing is an XY-Wing with a pivot cell of 16 in r9c8 and pincer cells of 12 in r1c9 and 26 in r8c7 (not r9c7). In an XY-Wing the pivot cell must "see" both pincer cells. The 16 cell does indeed see the 26 cell but does not see the 12 cell, therefore, it's not a valid XY-Wing.

Code: Select all

+--------------+--------+-------------+
| 1235 35  8   | 7 4  9 | 1236 136 12 |
| 2379 39  37  | 1 6  5 | 239  4   8  |
| 19   6   4   | 2 3  8 | 19   7   5  |
+--------------+--------+-------------+
| 4    8   15  | 3 9  7 | 15   2   6  |
| 359  359 2   | 8 15 6 | 7    13  4  |
| 6    7   135 | 4 15 2 | 135  8   9  |
+--------------+--------+-------------+
| 8    2   9   | 6 7  1 | 4    5   3  |
| 37   1   367 | 5 8  4 | 26   9   27 |
| 57   4   567 | 9 2  3 | 8    16  17 |
+--------------+--------+-------------+

[Solgor]

Thanks Marty R I now see my mistake. Notice that I used the word "lucky" in my post because I just couldn't believe that two moves would solve that puzzle. What about the remote pair (Kite)? Was that a legitimate move?

[Marty R.]

Thanks Marty R I now see my mistake. Notice that I used the word "lucky" in my post because I just couldn't believe that two moves would solve that puzzle. What about the remote pair (Kite)? Was that a legitimate move?

If you make the incorrect move based on the invalid XY-Wing, the puzzle would solve. Using the existing grid, I don't see a Kite or Remote Pair involving 1's in the cells mentioned.