## Gurth's Puzzles

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

### JADE RATINGS AND OYSTERS

JADE RATINGS AND OYSTERS

I think more now that the attempt to rate jades might end in the belief that it serves little purpose. It remains too subjective an appreciation. One can't count beauty, or compare them. We know what we like, and in any case we have the SE number to think about and the number of singles, apart from other factors less easy to enumerate.

In fact I like JPF's "challenger" as much as any of them.

OYSTERS:

My latest craving is for oysters. (No, I am not a pregnant woman.) Oysters can be with or without pearls. Pearl-oysters are hard then easy. The ultimate pearl-oyster would be a puzzle starting with one ultra-hard step followed by singles only. You only have to crack an oyster once. Is there such a thing?

Also good are oysters without pearls. They can start easy. But essentially the oyster makes its point once: it requires you to rise to a necessary level to achieve success. Once you have met that demand, it doesn't go on endlessly making the same demand on you again.

Even if there is no perfect oyster, I would like to get closer to the oyster ideal of short and sweet. Steps of maximum difficulty, but as few as possible.

A puzzle with say all singles except for one swordfish would be an acceptable oyster on the easier levels.

Any offerings? sorry I have none of my own.

_______________________________________________________________________
gurth

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

RW, my apologies for denying your 29 singles. As you rightly surmised, I got fooled by SE.
gurth

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

gurth wrote:My latest craving is for oysters. (No, I am not a pregnant woman.) Oysters can be with or without pearls. Pearl-oysters are hard then easy. The ultimate pearl-oyster would be a puzzle starting with one ultra-hard step followed by singles only. You only have to crack an oyster once. Is there such a thing?

The Effortless Extreme puzzles are all some kind of oysters, with the requirement of one hard move and the rest nothing more than singles, locked candidates, pairs and triplets. There's several puzzles there that need nothing but the one move and singles, can't remember straight away if there's any oysters with pearls. Personally I like oysters that can be cracked with some very simple, but rare, technique. Like this one from the Reverse BUG-lite thread:
Code: Select all
` *-----------*  |...|...|.83|  |..1|38.|.46|  |.23|...|.1.|  |---+---+---|  |7..|15.|.34|  |...|..7|8..|  |.6.|.4.|.7.|  |---+---+---|  |..5|8..|...|  |...|5..|...|  |2.7|4.1|...|  *-----------*`

Not quite a pearl, some singles available in the beginning, SE 7.8, make the Reverse BUG-lite elimination and it get's down to 2.8.

I also like oysters where the tough move is visible immediately in the starting grid, when you don't need to do any eliminations before you can use the "oyster cracking technique".

RW
RW
2010 Supporter

Posts: 1000
Joined: 16 March 2006

### Re: JADE RATINGS AND OYSTERS

gurth wrote:OYSTERS:
[...]
Also good are oysters without pearls. They can start easy. But essentially the oyster makes its point once: it requires you to rise to a necessary level to achieve success. Once you have met that demand, it doesn't go on endlessly making the same demand on you again.

Even if there is no perfect oyster, I would like to get closer to the oyster ideal of short and sweet. Steps of maximum difficulty, but as few as possible.

A puzzle with say all singles except for one swordfish would be an acceptable oyster on the easier levels.

Any offerings? sorry I have none of my own.

Here is an attempt on "Jade & Easy Oyster without pearl".
Code: Select all
`#Jade & Easy Oyster without pearl (M21).......12.1.....3..64...5......6.78......1......64.2......9...71..5.....4.72......`
Ocean

Posts: 442
Joined: 29 August 2005

gurth wrote:The ultimate pearl-oyster would be a puzzle starting with one ultra-hard step followed by singles only. You only have to crack an oyster once. Is there such a thing?

Still with Gordon’s help, here is a pearl-oyster :

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

S.S. : 1 locked candidates (1). End

S.E. : 1 Forcing X-Chain (SE = 6.7) : r6c8 <>8 and the puzzle is solved = 64 singles.

JPF
JPF
2017 Supporter

Posts: 3753
Joined: 06 December 2005
Location: Paris, France

An "easy" pearl-oyster.
XY-wing at start, after HD and ND. After the xy-wing, the rest is singles (but narrow path).
Code: Select all
`# "Easy" pearl-oyster with oyster symmetry...1...2...3.....4.5...6...7...1.5....2..4..3....6.7...7.......1.4..5..2...6...8..`
Ocean

Posts: 442
Joined: 29 August 2005

### Oysters and Jades

RW, Ocean and JPF,

Many thanks for your Oyster offerings. I'll have a meal!

Compare the two jades:
Code: Select all
`..6.7.45..1.8......2.......7...4....4......8.........1.8.2.....3.....7.....1.....  "newcomer" SE=8.3 n=37 mp=17..6...45..1.8......2....1....1.4....4......87...7...4..8.2.7...3.........7.1.....  GC01 SE=8.3 n=34 mp=20`

I have "doctored" NEWCOMER by shifting 3 7s and adding a few more clues to make it valid, getting a jade that is most excellent, yet can be viewed as just an inferior version of NEWCOMER.

My problem and question is this: Exactly how much doctoring does one have to do to any puzzle to earn the right to call the new puzzle one's own? ESPECIALLY IF THE NEW VERSION SEEMS WORSE THAN THE OLD? Anybody with any ideas that might give me food for thought?
_____________________________________________________________
gurth

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

Here is my contribution to jades.
It starts with 5 singles and then a SE step of rating 9.1.

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

Posts: 1174
Joined: 22 March 2006

### Fresh Oyster

GC04 : Easy Oyster

Fresh out of the sea this morning:

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

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

Mauricio, welcome to you and your heavyweight jade.

As heavyweights go, she's quite vicious. Even that Extreme heavyweight Jade, Ocean's "for gurth", after the 5 singles sweetener, slapped you in the face with a mere Turbot Fish before using chains on you.

Tarek's "Starter" was also considerate enough to slap you with a Turbot Fish before starting with the chains.

And even then, those gentle heavyweights used some 6.7 to 7.8 chains, before starting with the 9 plus stuff.

But no, your jade wastes no time in starting the rough stuff with a 9.1 chain!

I am endlessly fascinated by the range of personalities of sudokus, Turquoises, Pearls, Oysters and especially Jades.

What do you call her? Medea? Don't forget to give her credit for her full weight of 9.3 .

She also has 5 mutable clues, seems rather a lot for a 9.3 . You can put 6c3, 5d3, 2g7, 2h1 or 4k2: with what consequences I haven't checked.

___________________________
gurth

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

### La Generosa

GC06 : A Very Generous Jade

JPF, remember your jade Challenger, the one I said I liked so much? Here's a companion for it, nearly as generous with 31 starting singles, a bit tougher at SE 7.1 :

Code: Select all
`#La Generosa (GC06)  . . . . . . 8 . .  9 . . . 4 . . 6 .  . 2 . . 6 8 . . 5  . 3 . . . . . . .  . 4 . . 5 . . . .  . . 6 . . . 7 9 8  . . 1 3 . 6 . . 4  . . . 4 . . . 5 .  2 . . 5 7 . 6 . .`

At old ratings:
Challenger .............. : JR = 6.6 x 34 = 224.4
La Generosa (GC06) : JR = 7.1 x 31 = 220.1

- A well-matched pair. Mine also has a Turbot Fish.

__________________________________________________________________________________
gurth

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

daj95376 said:
Are there two Sashimi X-Wings in <1> (as well) that would produce the same eliminations?

Code: Select all
` *-----------*  |...|...|8..|  |9..|.4.|.6.|  |.2.|.68|..5|  |---+---+---|  |.3.|...|...|  |.4.|.5.|...|  |..6|...|798|  |---+---+---|  |..1|3.6|..4|  |...|4..|.5.|  |2..|57.|6..|  *-----------* # gurth GC06  `

Code: Select all
`# at this point, Coloring could be used for these eliminations in <1>  *-----------------------------------------------------------*  | 4     6     5     | 1     2     3     | 8     7     9     |  | 9     1     8     | 7     4     5     | 23    6     23    |  | 3     2     7     | 9     6     8     | 4     1     5     |  |-------------------+-------------------+-------------------|  | 78    3     29    | 68   G19    179   | 5     4     26-1  |  | 78    4     29    | 68    5     79-1  |B123   23    1236  |  | 1     5     6     | 2     3     4     | 7     9     8     |  |-------------------+-------------------+-------------------|  | 5     7     1     | 3     89    6     | 29    28    4     |  | 6     89    3     | 4    B189   2     |G19    5     7     |  | 2     89    4     | 5     7     19    | 6     38    13    |  *-----------------------------------------------------------*  `

The 2 Sashimi X-Wings looks like a turbot with a force.

I can't see a solution or what is next. Help

dan
dan

ArkieTech

Posts: 2712
Joined: 29 May 2006
Location: NW Arkansas USA

With Carcul's solution of gurth GC06 :
[r8c2]=8=[r9c2]=9=[r9c6]=1=[r9c9]-1-[r8c7]-9-[r8c2], => r8c2<>9 solving the puzzle.

The Sashimi X-Wings do not contribute to the solution.

dan
dan

ArkieTech

Posts: 2712
Joined: 29 May 2006
Location: NW Arkansas USA

ArkieTech wrote:With Carcul's solution of gurth GC06 :
[r8c2]=8=[r9c2]=9=[r9c6]=1=[r9c9]-1-[r8c7]-9-[r8c2], => r8c2<>9 solving the puzzle.

The Sashimi X-Wings do not contribute to the solution.

dan

ArkieTech, There are at least three chains -- [r7c2]<>2, [r9c2]<>8, and [r9c6]<>9 -- that will crack open the original puzzle without ever examining so much as an initial Naked/Hidden Single. However, some people frown at jumping over basic and lesser techniques to reach a solution.
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

On the same lines of my previous posted sudoku, I found this in the hardest sudoku thread, it starts with 5 singles, and then a 9.2 step, final rating 9.9
Code: Select all
`9....67...4..3......71....4..8.....6.2..1..8.6....49..1....2..8.5..7..2....3..6..`

A few nice jades:
Code: Select all
`100008009400000002080400030004009070007000000000300005070006900060100800000502006SE 7.3, 40 singles`

Code: Select all
`103060008056000200000024300004085009900001000000047100000000703008000005000800006SE 8.3, 31 singles`

Code: Select all
`100597600000000900080004020902000008560021000000040000000000890000032706640000000SE 8.4, 27 singles`

Code: Select all
`120804000050000002000503060000039050000600000307002100000000075000108000004370000SE 9.0, 18 singles`

Code: Select all
`000050400050300000000002001007000080800000070090800003041009600600100207000003000SE 9.1, 13 singles`

Code: Select all
`023000004000000070080500600008040009000001046000600000090087000304000000002093010000000009406080100009000450000300608000070000008910045800204000004067090000890000SE 9.2, 11 singles`

Edit: Corrected a few typos when I changed 0's by .'s. I like 0's more.
Last edited by Mauricio on Thu Dec 07, 2006 2:40 pm, edited 1 time in total.
Mauricio

Posts: 1174
Joined: 22 March 2006

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