## Sudokus with an original rare shape

Everything about Sudoku that doesn't fit in one of the other sections
You can't proof that there are least 2 solutions whenever you have a deadly pattern or 2 not-used digits. In the first case must in the second can the sudoku have none solution.
Pyrrhon

Posts: 240
Joined: 26 April 2006

JPF wrote:Try this site

JPF

It's an interesting little tool! However, after a few hundred attempts I've given up on it ever creating anything beyond easy puzzles. Am I missing something in the translation?
Deano

Posts: 2
Joined: 29 March 2006

Deano wrote:
JPF wrote:Try this site

JPF

It's an interesting little tool! However, after a few hundred attempts I've given up on it ever creating anything beyond easy puzzles. Am I missing something in the translation?

No. I'm not absolutely *sure* that it won't create harder puzzles, but I haven't seen one. Most methods of creating puzzles will create far more easy ones than hard ones, regardless of how you define "easy" and "hard" -- but it may be that the method used on that page is even less likely or impossible to create harder ones. If -- and I'm guessing -- it creates puzzles by randomly adding digits to the template and then testing for solvability -- and if the sovablity test is a set of logical tactics instead of a brute force search, it will *only* return those that are solvable with those rules. Since it's a Japanese site that's been around for several years, the target would likely be less than x-wing level puzzles.

I've found it interesting that some templates entered in this applet will make puzzle very quickly -- the same template entered in Michael Kennett's program might run for many minutes without finding one. And yet another template might have the opposite results. Kennett's program will make puzzles of a much wider range of difficulty.
tso

Posts: 798
Joined: 22 June 2005

### double hearts

Hi,

here is another heart-attack.
Code: Select all
`. 9 5|6 . 7|3 2 . 2 . .|. 5 .|. . 4 . . 8|. . .|6 . . ------------------ . . 3|. 1 .|5 . . 1 . .|9 . 5|. . 8 . 4 .|. 3 .|. 6 . ------------------ . . 1|. . .|9 . . . . .|5 . 3|. . . . 8 .|. 4 .|. 5 . double heart `

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

Here's one with 4 little rectangles, easy but pretty.

Code: Select all
`  .  .  .  .  .  .  .  .  .                          .  5  2  4  .  7  6  3  .  .  8  .  3  .  1  .  4  .  .  3  7  5  .  9  2  6  .  .  .  .  .  .  .  .  .  .  .  6  4  1  .  2  7  8  .  .  2  .  9  .  3  .  1  .  .  9  5  8  .  6  3  2  .  .  .  .  .  .  .  .  .  .`

Regards,

Mike Metcalf

m_b_metcalf
2017 Supporter

Posts: 9284
Joined: 15 May 2006
Location: Berlin

m_b_metcalf wrote:Here's one with 4 little rectangles, easy but pretty.

Five of the same pattern, in increasing difficulty:
Code: Select all
`+-------+-------+-------+| . . . | . . . | . . . | | . 3 8 | 5 . 9 | 4 6 . | | . 9 . | 3 . 2 | . 5 . | +-------+-------+-------+| . 2 9 | 4 . 5 | 7 8 . | | . . . | . . . | . . . | | . 5 1 | 6 . 7 | 2 4 . | +-------+-------+-------+| . 1 . | 9 . 3 | . 2 . | | . 7 5 | 8 . 4 | 1 3 . | | . . . | . . . | . . . | +-------+-------+-------++-------+-------+-------+| . . . | . . . | . . . | | . 6 1 | 4 . 9 | 7 2 . | | . 5 . | 7 . 1 | . 8 . | +-------+-------+-------+| . 8 2 | 6 . 4 | 3 1 . | | . . . | . . . | . . . | | . 3 7 | 1 . 2 | 5 6 . | +-------+-------+-------+| . 2 . | 3 . 8 | . 7 . | | . 9 4 | 2 . 6 | 1 3 . | | . . . | . . . | . . . | +-------+-------+-------++-------+-------+-------+| . . . | . . . | . . . | | . 9 3 | 6 . 8 | 5 4 . | | . 4 . | 1 . 3 | . 8 . | +-------+-------+-------+| . 3 8 | 5 . 2 | 7 1 . | | . . . | . . . | . . . | | . 2 9 | 3 . 1 | 8 5 . | +-------+-------+-------+| . 5 . | 4 . 7 | . 6 . | | . 7 6 | 2 . 5 | 9 3 . | | . . . | . . . | . . . | +-------+-------+-------++-------+-------+-------+| . . . | . . . | . . . | | . 2 5 | 4 . 7 | 1 9 . | | . 8 . | 3 . 9 | . 2 . | +-------+-------+-------+| . 1 3 | 5 . 4 | 9 7 . | | . . . | . . . | . . . | | . 6 9 | 2 . 3 | 4 1 . | +-------+-------+-------+| . 5 . | 9 . 2 | . 4 . | | . 4 7 | 6 . 5 | 3 8 . | | . . . | . . . | . . . | +-------+-------+-------++-------+-------+-------+| . . . | . . . | . . . | | . 3 8 | 4 . 9 | 2 6 . | | . 4 . | 2 . 8 | . 1 . | +-------+-------+-------+| . 5 7 | 8 . 6 | 1 3 . | | . . . | . . . | . . . | | . 8 2 | 5 . 1 | 9 7 . | +-------+-------+-------+| . 9 . | 7 . 2 | . 5 . | | . 2 5 | 1 . 3 | 6 8 . | | . . . | . . . | . . . | +-------+-------+-------+`
tso

Posts: 798
Joined: 22 June 2005

Surprising hard puzzles. For the last one i needed a very long chain.
ravel

Posts: 998
Joined: 21 February 2006

Here's a band plus dot that I came up with:

Code: Select all
`  .  .  .  .  .  .  .  8  3  .  .  .  .  .  .  7  1  9  .  .  .  .  .  6  2  5  .  .  .  .  .  3  4  8  .  .  .  .  .  6  2  9  .  .  .  .  .  4  8  7  .  .  .  .  .  6  8  1  .  .  .  .  .  2  3  7  .  .  .  .  .  .  1  5  .  .  .  .  .  .  2`

Regards,

Mike Metcalf

m_b_metcalf
2017 Supporter

Posts: 9284
Joined: 15 May 2006
Location: Berlin

Nice,
Of course, you can do it dotless...

Code: Select all
` . . . . . . . 9 7 . . . . . . 2 6 1 . . . . . 3 4 8 . . . . . 3 4 5 . . . . . 6 2 8 . . . . . 6 1 9 . . . . . 9 7 2 . . . . . 8 6 2 . . . . . . 4 3 . . . . . . .`

JPF
JPF
2017 Supporter

Posts: 3754
Joined: 06 December 2005
Location: Paris, France

The slash patten is a nice one.

I went to Puzzle Laboratory and very quickly created several puzzles using this mask. Of course they were easy puzzles, as this applet -- as far as I know -- only creates puzzles that can be solved completely with singles. Then, I tried to use Michael Kennett's program, using the same mask:

Code: Select all
`%.......**......***.....***.....***.....***.....***.....***.....***......**.......`

I let it run for about twenty minutes and it found nothing. Since Michael's program can find puzzles of all difficulty levels given other templates with the same number of clues -- in some cases finding hundreds or thousands a minute, this is baffling to a non-programmer layperson.

Why do you suppose this is?
tso

Posts: 798
Joined: 22 June 2005

tso wrote:Then, I tried to useMichael Kennett's program, using the same mask:

[snip]

I let it run for about twenty minutes and it found nothing. Since Michael's program can find puzzles of all difficulty levels given other templates with the same number of clues -- in some cases finding hundreds or thousands a minute, this is baffling to a non-programmer layperson.

Why do you suppose this is?

I am similarly perplexed. I have two completely independent programs to generate puzzles from templates. One is based on a randomised brute force generator with a brute force solver, the other on a completely random generator with a logic solver. For the band plus dot, each requires only a few seconds to generate a valid puzzle. Without the dot, I have run each for an hour real time at 1.6GHz, equivalent to about 1 million attempts each, and neither gets a hit. What's so special about this template?

Regards,

Mike Metcalf

[Edit added years later: Now, thankfully, new versions are more successful.]
Last edited by m_b_metcalf on Mon Jan 09, 2012 10:55 pm, edited 1 time in total.

m_b_metcalf
2017 Supporter

Posts: 9284
Joined: 15 May 2006
Location: Berlin

### Simply Loving Hearts

tso wrote:
m_b_metcalf wrote:Here's one with 4 little rectangles, easy but pretty.

Five of the same pattern, in increasing difficulty:

I like these edge-nontouching rectangles. Mostly they are pretty hard but tasty nuts to crack.

This day I tried to refine a previous puzzle of mine.

I came out with this:

Code: Select all
`+-------+-------+-------+| . . 9 | 1 . 2 | 7 . . | | . 3 . | . 4 . | . 1 . | | . . 2 | . . . | 6 . . | +-------+-------+-------+| . . . | 3 . 4 | . . . | | . . . | . 8 . | . . . | | . . . | 9 . 7 | . . . | +-------+-------+-------+| . . 5 | . . . | 2 . . | | . 1 . | . 9 . | . 4 . | | . . 7 | 6 . 5 | 9 . . | +-------+-------+-------+Simply loving hearts`

Unfortunately this was not that simple in creation because despite restless trial I couldn't eliminate two naked pairs which make the sudoku bi-solutional. It's the notorious 4/77-thing. But because the two confused numbers shouldn't affect the solving that much and I consider this beautiful I hope you will forgive me.

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

I like the bar shape

here's one that needs locked candidates:
Code: Select all
` . . . | . . . | . 6 2  . . . | . . . | 9 8 4  . . . | . . 2 | 5 3 .  ------+-------+------  . . . | . 2 9 | 1 . .  . . . | 6 4 7 | . . .  . . 6 | 5 8 . | . . .  ------+-------+------  . 9 8 | 4 . . | . . .  2 5 7 | . . . | . . .  6 3 . | . . . | . . . `

here's a slight variation on the pattern, but an easy puzzle:
Code: Select all
` . . . | . . . | . 9 5  . . . | . . . | 3 6 1  . . . | . . 2 | . 4 .  ------+-------+------  . . . | . 5 8 | 4 . .  . . . | 1 7 4 | . . .  . . 5 | 9 6 . | . . .  ------+-------+------  . 7 . | 6 . . | . . .  2 8 3 | . . . | . . .  1 4 . | . . . | . . . `

and here's a real sudoku with your hearts Claudia:
Code: Select all
` . . 1 | 5 . 9 | 2 . .  . 8 . | . 7 . | . 9 .  . . 3 | . . . | 4 . .  ------+-------+------  . . . | 1 . 4 | . . .  . . . | . 5 . | . . .  . . . | 6 . 2 | . . .  ------+-------+------  . . 6 | . . . | 1 . .  . 5 . | . 3 . | . 7 .  . . 7 | 2 . 8 | 3 . . `
ab

Posts: 451
Joined: 06 September 2005

### Simply Loving Hearts - Real Sudoku

ab wrote:.... and here's a real sudoku with your hearts Claudia:...

Hi ab

Thank you very much. I knew, somebody of you will tackle the challenge.

With best wishes

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

here's a puzzle with the slash mask that needs xy wings:
Code: Select all
` . . . | . . . | . 4 9  . . . | . . . | 8 5 1  . . . | . . 8 | 7 6 .  ------+-------+------  . . . | . 3 1 | 2 . .  . . . | 5 2 7 | . . .  . . 5 | 4 9 . | . . .  ------+-------+------  . 9 4 | 3 . . | . . .  5 2 1 | . . . | . . .  6 8 . | . . . | . . . `
ab

Posts: 451
Joined: 06 September 2005

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