## Sudokus with an original rare shape

Everything about Sudoku that doesn't fit in one of the other sections

### Re: not really difficult ...

claudiarabia wrote:...Suggestions to make this pattern more difficult are welcome.

Another puzzle in the same nice pattern (ER 9.7):
Code: Select all
` 1 . . . . . . . 2  . 3 . . 4 . . 5 .  . . . 6 . 7 . . .  . . 4 . . . 6 . .  . 7 . . 8 . . 4 .  . . 9 . . . 8 . .  . . . 9 . 8 . . .  . 2 . . 7 . . 1 .  5 . . . . . . . 3 `
Ocean

Posts: 442
Joined: 29 August 2005

Ocean wrote:
Code: Select all
`1.......2.3..4..5....6.7.....4...6...7..8..4...9...8.....9.8....2..7..1.5.......3`

It's a nice tough pearl alright...

Here is the solution:

146853792
738249156
295617384
854792631
672381549
319465827
461938275
923576418
587124963

Under SSTS, there are 5 backdoor cells:

r3c1=2 (naked pairs)
r5c3=2 (naked triples)
r5c7=5 (naked triples)
r7c9=5 (naked triples)
r9c2=8 (naked pairs)

But they all require pairs/triples so under singles there are no backdoor cells.

So roughly speaking it's also a diamond (under singles), but not as many carats as the following (also Ocean's puzzle):
Code: Select all
`.....1..2.3..4..5.6..2.......5.....3.7..8..4.2.....9..9....4.......5..7...41..6..`

... Which has no backdoor cells whatsoever under SSTS...

... And tested those 5 backdoor cells, none of them are ruby cells...

Hopefully in the future someone could also define properties for sapphire/emerald/jade etc...
udosuk

Posts: 2698
Joined: 17 July 2005

### Re: not really difficult ...

Ocean wrote:Another puzzle in the same nice pattern (ER 9.7):
Code: Select all
` 1 . . . . . . . 2  . 3 . . 4 . . 5 .  . . . 6 . 7 . . .  . . 4 . . . 6 . .  . 7 . . 8 . . 4 .  . . 9 . . . 8 . .  . . . 9 . 8 . . .  . 2 . . 7 . . 1 .  5 . . . . . . . 3 `

It has 8 Dynamic Double Forcing Chains (+) unexpectedly.
Eioru

Posts: 182
Joined: 16 August 2006

### really difficult!

Ocean wrote:
claudiarabia wrote:...Suggestions to make this pattern more difficult are welcome.

Another puzzle in the same nice pattern (ER 9.7):
Code: Select all
` 1 . . . . . . . 2  . 3 . . 4 . . 5 .  . . . 6 . 7 . . .  . . 4 . . . 6 . .  . 7 . . 8 . . 4 .  . . 9 . . . 8 . .  . . . 9 . 8 . . .  . 2 . . 7 . . 1 .  5 . . . . . . . 3 `

I always was sure that you can make ER 9er puzzles with this pattern. As it seems you nead a cluster of the same number sometimes to produce such like here the Nr. 8.

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

### two diamonds

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

My first puzzle in this forum was this. It was not minimal, I didn't put in on the right place in this forum and it was not really difficult.

I thought it's time to make something more advanced diagonal lining out of it and this came out:

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

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

Does anyone recall where the general pattern below -- including r6c7 and r7c6 as possible clue locations -- has been searched?

Code: Select all
` ..8|..3|..7 .9.|.8.|.6. 5..|1..|2.. ---+---+--- ..2|..6|..1 .4.|.9.|.7. 9..|5..|... ---+---+--- ..5|...|..3 .7.|.3.|.2. 3..|2..|4..    ER=9.0`

TIA, Ron
ronk
2012 Supporter

Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

Ocean sent 2 collections with the diagonal pattern to the hardest thread here and here.
ravel

Posts: 998
Joined: 21 February 2006

Only find 4
....1..23.4.5......3...61...7..6....8.345..1...1..8..47..6..3...6..8.........259.
...1.2.....34......5..6..7.31.....48..4...5..29......3.8..7..1...76.58.....8.9...
...1.2.....34.51...6..7..5.31.....4...4...6..28.....73.9..5..1...57.69.....9.8...
...1..2....2..3.4..56...7.35...2..8....5.7....6..4...56.9...83..7.2..1....3..6...

and I spent 2 days just find a puzzle same pzttern with
Code: Select all
` 1 . . . . . . . 2  . 3 . . 4 . . 5 .  . . . 6 . 7 . . .  . . 4 . . . 6 . .  . 7 . . 8 . . 4 .  . . 9 . . . 8 . .  . . . 9 . 8 . . .  . 2 . . 7 . . 1 .  5 . . . . . . . 3  `

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

But, it's so easy...
Eioru

Posts: 182
Joined: 16 August 2006

### here is some diagonal stuff

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

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

### Re: here is some diagonal stuff

4 patterns :

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

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

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

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

JPF
JPF
2017 Supporter

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

Udosuk wrote...

Ocean wrote:
Code:
1.......2
.3..4..5.
...6.7...
..4...6..
.7..8..4.
..9...8..
...9.8...
.2..7..1.
5.......3

It's a nice tough pearl alright..."

Yes, indeed, I found placing the first cell harder than the rest of the puzzle put together! It took me 10 Forcing Nets to get that first cell, and another two to finish the puzzle.

For interest's sake: I tried a total of 17 starting candidates in finding this solution path. Only 5 of them failed to establish a contradiction using SSTS only, so I scrapped them, leaving the 12 successful steps recorded below. I made no subsequent attempt to shorten the path. How can you shorten a job by continuing after it is finished?

SOLUTION :

Steps 1 to 4 examined ?6b1, ?6e3, ?4g7, and ?2k8, leading to ?? each time and achieving nothing beyond eliminating those candidates.

5. ? 2k7, SSTS, ?? -2k7, -2g5.

Steps 6 to 9 examined ?2b1, ?1b9, ?1c9, and ?1g2, leading to ?? and the elimination of these candidates; step 9 was a particularly long one, requiring XY Wings and Multiple Colors.

10. ? 4g2, SSTS, ?? -4g2, 6g2 (THE FIRST CELL SOLVED !), followed by many exclusions, suddenly creating a mass of bivalue cells where before there were none.

11. ? 6f1, SSTS, ?? -6f1, 6e1, SSTS.

12. ? 7g1, SSTS, -7g1, 4g1, SSTS to end of solution.

FURTHER COMMENT :
I am so impressed by the beauty of this huge and flawless pearl that I propose to name it OCEAN'S PEARL BROOCH, subject to the approval of Ocean himself.

The BROOCH referring to the symmetrical shape. I must confess that this puzzle has converted me to an appreciation of symmetry as an aesthetic value, provided of course it does not entail the horrible sin of redundancy.
gurth

Posts: 358
Joined: 11 February 2006
Location: Cape Town, South Africa

gurth wrote:Yes, indeed, I found placing the first cell harder than the rest of the puzzle put together! It took me 10 Forcing Nets to get that first cell, and another two to finish the puzzle.

Thanks for solving and analyzing the puzzle! Glad you liked it!
gurth wrote:I am so impressed by the beauty of this huge and flawless pearl that I propose to name it OCEAN'S PEARL BROOCH, subject to the approval of Ocean himself.

The BROOCH referring to the symmetrical shape. I must confess that this puzzle has converted me to an appreciation of symmetry as an aesthetic value, provided of course it does not entail the horrible sin of redundancy.

It's an honour when a puzzle is getting it's own name! Somehow it is satisfactory to find hard puzzles which have nice symmetry and at the same time no redundant clues, combining solving aestetics and symmetry aestetics.
Ocean

Posts: 442
Joined: 29 August 2005

### Ocean's Pearl Brooch

Report to Ocean :

For practice, I redid your Pearl Brooch from start, remembering nothing of my first solution. This time I took 5 steps to get the first cell 6g2, one more step to reach the end :

1. ? 7k8, SSTS, ?? -7k8, SSTS (-7b7).

2. ? 7a3, singles, ?? -7a3, -7b9.

3. ? 7g9, SSTS, ?? -7g9, SSTS.

4. ? 4g2, SSTS, ?? -4g2.

5. ? 1g2, SSTS, -1g2, 6g2 (the first cell!), and a lot more using SSTS.

6. ? 2c3, singles, ?? -2c3, 5c3, singles to end.
gurth

Posts: 358
Joined: 11 February 2006
Location: Cape Town, South Africa

### Almost fully symmetric with an almost symmetric swordfish

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

A star was born - I want to make it a present for you on my birthday.

Claudia
claudiarabia

Posts: 288
Joined: 14 May 2006

### Re: Almost fully symmetric with an almost symmetric swordfis

claudiarabia wrote:
Code: Select all
`4 . . . . . . . 9. . . . 7 . . . .. . 3 4 . 2 8 . .. . 1 . . 9 6 . .. 8 . . 3 . . 7 .. . 2 5 . . 4 . .. . 5 6 . 1 3 . .. . . . 8 . . . .9 . . . . . . . 2     Arabian Star`

A star was born - I want to make it a present for you on my birthday.

Claudia

Thanks & Happy birthday !

Here is a modest gift :

(E5 : 3->6 or B5 : 8->6) => SE 8.4 -> 8.9

JPF
JPF
2017 Supporter

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

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