The New Sudoku Players' Forum

[m_b_metcalf]

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 . . 1 . 2 . . . .
 3 4 . . . . 5 6 .
 . . . . . 7 . . .
 . 8 . . . . . . .
 1 7 . . . . . 2 8
 . . . . . . . 5 .
 . . . 4 . . . . .
 . 5 3 . . . . 1 6
 . . . . 1 . 9 . .  x-sudoku

..1.2....34....56......7....8.......17.....28.......5....4......53....16....1.9..

[Leren]

xbtte. Leren

[Hajime]

xbtte. Leren

Except for the Generalized Intersection, halfway the solution path:

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(9)r5c3\ => (-9)r7c3 | (9)\r5c3 => (-9)r5c3 | (9)r5b5 => (-9)r4c4 (-9)r6c6 | (9)r5c5 => (-9)r2c5 (-9)r8c5 | (9)c3r6b4 => (-9)r6c1 | (9)r7c1 => (-9)r4c1

(9)r5c3\ means that candidate 9 is locked in r5, c3 and the diagonal.

[m_b_metcalf]

Another:

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 . . . . . . . . .
 . . 1 . . . . . .
 2 . . 3 4 5 6 . .
 . . . . . . . 7 .
 . 4 7 . . . 5 8 .
 . 5 . . . . . . .
 . . 9 2 8 6 . . 1
 . . . . . . 4 . .
 . . . . . . . . .   x-sudoku

...........1......2..3456.........7..47...58..5.........9286..1......4...........


Mike

[Hajime]

Another: ...
Mike

And one for you:

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. . 2 . . . 8 . .
. . 9 . . . 3 . .
. . 7 6 . 2 1 . .
. 7 . . 4 . . 1 .
. . . 8 . 7 . . .
. 5 4 . 6 . 7 2 .
. . 8 2 . 9 4 . .
. . 5 . . . 2 . .
. . 1 . . . 5 . .   x-sudoku
                 
..2...8....9...3....76.21...7..4..1....8.7....54.6.72...82.94....5...2....1...5..


[Leren]

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*--------------------------------------------------------------*
| 5678  69   1     | 35689   2      345689 | 3478  34789 3479  |
| 3     4    278   | 189     89     189    | 5     6     1279  |
| 2568  269  2568  | 135689  345689 7      | 2348  3489  12349 |
|------------------+-----------------------+-------------------|
| 24569 8    24569 | 235679  34567  1234   | 13467 3479  3479  |
| 1     7   a4569  | 356    b39     3456   | 346   2     8     |
| 2469  3    2469  | 1278    4678   2689   | 1467  5     479   |
|------------------+-----------------------+-------------------|
| 26789 1   c278-9 | 4       356789 235689 | 2378  378   2357  |
| 24789 5    3     | 2789    789    289    | 2478  1     6     |
| 2478  26   24678 | 235678  1      23568  | 9     3478  2357  |
*--------------------------------------------------------------*

The move referred to by Hajime is shown in cells marked a, b and c. There are two 9's in Row 5 in cells a and b, and one of them is on a diagonal, so you can remove the 9 from cell c. You could also have removed a 9 from r3c3 had one been there.

Well, I think this is pretty basic, certainly no harder than the so called pointing pairs and triples on a diagonal that Andrew Stuart's solver uses. For some reason it doesn't see this easy move. An oversight IMHO.

Leren

[m_b_metcalf]

And one for you:

Thanks, but too hard for me

[Leren]

m_b_metcalf wrote : Thanks, but too hard for me

I think he might be having us on . You can get to here with basic moves (including one "generalised Intersection").

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*--------------------------------------------------------------------------------*
| 356     1       2        | 347     379     345      | 8       45679   67       |
| 456     68      9        | 1457    178     48       | 3       567     2        |
| 345     348     7        | 6       389     2        | 1       459     45       |
|--------------------------+--------------------------+--------------------------|
| 2       7       6        | 35      4       35       | 9       1       8        |
| 1       9       3        | 8       2       7        | 6       45      45       |
| 8       5       4        | 9       6       1        | 7       2       3        |
|--------------------------+--------------------------+--------------------------|
| 367     36      8        | 2       5       9        | 4       367     1        |
| 9       34      5        | 1347    1378    3468     | 2       368     67       |
| 3467    2       1        | 347     378     3468     | 5       3678    9        |
*--------------------------------------------------------------------------------*

Leren

[Hajime]

Thanks, but too hard for me

Needed are a genuine 2string-kite, a genuine skyscraper and a similar on a diagonal.
I could not solve your puzzle also, manually

[Leren]

Hajime, for the second puzzle you should be able to get to here with basic moves. Do the two * cells suggest anything ?

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*--------------------------------------------------------------------------------*
| 3679    3679    4        | 16789   2679    12789    | 23789   239     5        |
| 5       3679    1        | 6789    2679    2789     | 23789   4       23789    |
| 2       79      8        | 3       4       5        | 6       1       79       |
|--------------------------+--------------------------+--------------------------|
| 13689   13689   236      | 5       2369    238      | 1239    7       4        |
| 369     4       7        | 69      1       239      | 5       8       2369     |
| 13689   5       236      | 78      23679   4        | 1239    2369    2369     |
|--------------------------+--------------------------+--------------------------|
| 4      *37      9        | 2       8       6        |*37      5       1        |
| 13678   237     356      | 179     3579    1379     | 4       2369    36789    |
| 37      123678  356      | 4       3579    1379     | 3789    369     23679    |
*--------------------------------------------------------------------------------*

Leren

[m_b_metcalf]

Needed are a genuine 2string-kite, a genuine skyscraper and a similar on a diagonal.
I could not solve your puzzle also, manually

The first puzzzle has a naked quad, the second an xy-wing. But all roads lead to Rome.

Mike

[Leren]

Hi Mike,

The theme of this thread is well taken though. In X solving there are often a lot of intersection moves and it's easy for a manual solver to miss one, making an otherwise easy puzzle seem hard.

Leren

[Leren]

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*-----------*
|...|...|...|
|...|...|...|
|...|...|...|
|---+---+---|
|...|...|...|
|...|...|.12|
|.3.|.45|...|
|---+---+---|
|.5.|...|67.|
|...|2.8|...|
|...|1..|4..|
*-----------*
...........................................12.3..45....5....67....2.8......1..4..

Here is a puzzle from me. Only 12 clues. This should be tough.

Leren

[m_b_metcalf]

Here is a puzzle from me. Only 12 clues. This should be tough.

Took me half-an-hour. It's a slog, but only pointing, pairs and triples, no intersections or harder.

mike

[Hajime]

It took me about an hour. My human skills are about SER = 4.5.
Sometimes I can solve a 5.5 and sometimes not even a 3.5.
With my solver the sky is the limit. All my puzzles are generated using SiSeSuSo.
And then I choose a nice puzzle conform the goal of the forum-subject.

I liked my puzzle with the 3 X-chains of length 4 cells (skyscraper, 2string-kite and the diagonal X-chain).
It was the hardest of 50 generated puzzles and is reaching the ceiling of most human solvers.