The New Sudoku Players' Forum

[m_b_metcalf]

Code: Select all

 . . 1 . . . . . 2
 . 6 . 9 . . . 7 .
 9 . . . 7 . 8 . .
 . 1 . . . 2 . . .
 . . 3 . 4 . 5 . .
 . . . 8 . . . 1 .
 . . 2 . 5 . . . 7
 . 3 . . . 9 . 6 .
 8 . . . . . 3 . .   Symmetry of givens, formally very hard

..1.....2.6.9...7.9...7.8...1...2.....3.4.5.....8...1...2.5...7.3...9.6.8.....3..

[Cenoman]

Code: Select all

 +---------------------------+--------------------------+-------------------------+
 |  45-37   4578    1        |  3456     368    34568   |  469     3459   2       |
 |  2345    6       458      |  9        1238   13458   |  14      7      1345    |
 |  9       245     45       |  123456   7      13456   |  8       345    13456   |
 +---------------------------+--------------------------+-------------------------+
 |  4567    1       456789   |  56-37     369    2      |  4679    3489   34689   |
 |  267     2789    3        |  167      4      167     |  5       289    689     |
 |  24567   24579   45679    |  8        369    56-37   |  24679   1      3469    |
 +---------------------------+--------------------------+-------------------------+
 |  146     49      2        |  1346     5      13468   |  4-19    489    7       |
 |  1457    3       457      |  1247     128    9       |  124     6      1458    |
 |  8       4579    45679    |  12467    126    1467    |  3       2459   45-19   |
 +---------------------------+--------------------------+-------------------------+

Main diagonal automorphism with digit permutation [19] [28] [37] [4] [5] [6] => main diagonal solutions all in {4,5,6} => -37 r1c1, r4c4, r6c6, -19 r7c7, r9c9; ste

[philvo]

Nice symmetric puzzle.
phil

[m_b_metcalf]

Nice symmetric puzzle.
phil

Thanks. It's a slight variation on one provided by jpf. With rotational symmetry, one can go even higher in difficulty:

Code: Select all

 . . 1 . . . . . 2
 . 5 . 7 . . . 3 .
 6 . . . 1 . 5 . .
 . 9 . . . 2 . . .
 . . 6 . 5 . 4 . .
 . . . 8 . . . 1 .
 . . 5 . 9 . . . 4
 . 7 . . . 3 . 5 .
 8 . . . . . 9 . .   #4A

..1.....2.5.7...3.6...1.5...9...2.....6.5.4.....8...1...5.9...4.7...3.5.8.....9..

[Hajime]

I found this morph in ph2010 nr ;9798

Code: Select all

  . . 4 . . . . . 7
  . 8 . 7 . . . 9 .
  6 . . . 5 . 8 . .
  . 2 . . . 1 . . .
  . . 3 . 8 . 4 . .
  . . . 9 . . . 7 .
  . . 8 . 6 . . . 1
  . 1 . . . 2 . 5 .
  5 . . . . . 3 . .  ED=10.5


[eleven]

With rotational symmetry, one can go even higher in difficulty:

Code: Select all

..1.....2.5.7...3.6...1.5...9...2.....6.5.4.....8...1...5.9...4.7...3.5.8.....9..

In spite of the symmetry this one seems to be very hard.

[m_b_metcalf]

With rotational symmetry, one can go even higher in difficulty:

Code: Select all

..1.....2.5.7...3.6...1.5...9...2.....6.5.4.....8...1...5.9...4.7...3.5.8.....9..

In spite of the symmetry this one seems to be very hard.

It is, just shy of 10.0. And even though it has a backdoor, that's impossible (for me) to spot.

Mike

[Hajime]

I found this morph in ph2010 nr ;9798 .....

But also a nice diamond is available (hard):

Code: Select all

..4.....3.5.1...7.6...2.5...9...2.....2.5.4.....8...1...5.9...6.7...3.5.8.....9..   ED=10.6/10.6/10.6

[m_b_metcalf]

But also a nice diamond is available (hard):

Code: Select all

..4.....3.5.1...7.6...2.5...9...2.....2.5.4.....8...1...5.9...6.7...3.5.8.....9..   ED=10.6/10.6/10.6

More can be seen for an almost identical pattern in the results of PG91 . Of course, these puzzles don't have symmetry of the givens.

Mike