G929 : Third Pearl of September

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

G929 : Third Pearl of September

Postby gurth » Mon Oct 02, 2006 8:29 am

G929 : Third Pearl of September.

(G910 was my first of that month; G913, the second, is not yet published. Not that she has anything to be ashamed about; quite the contrary.)

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

 |.9.|.3.|.7.|
 |...|..7|..2|
 |---+---+---|
 |6..|..8|..4|
 |.5.|.4.|.8.|
 |..9|...|1..|
 *-----------*


It's a full-size pearl, requiring more than SSTS to get the first cell. Exactly how difficult I don't know, as I don't rush to solve my own puzzles, but maybe JPF will oblige once more with an SE rating and report on touchability. I suspect this puzzle will be a bit easier than G910, because you can eliminate more candidates at the start.

It's also the first time I have considered shape. There is one diagonal axis of symmetry. If I had to give it a title I might say Vase with Flowers, or maybe Lamp with Shade.

There is also a certain symmetry about the digits, but it is not perfect.
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Re: G929 : Third Pearl of September

Postby ravel » Mon Oct 02, 2006 11:01 am

gurth wrote:Exactly how difficult I don't know, as I don't rush to solve my own puzzles ...

ER 9.1, gsf 99384, can be solved with 1 step: r7c3<>3 or r8c3<>1 (both need pairs).
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Postby JPF » Mon Oct 02, 2006 11:20 am

This is not an Untouchable.
E5 : 3->8 gives the same SE rating 9.1

With permutaions of col. (1,3) & row (7,9) the Vase with Flowers looks like a zebra :

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

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Postby ravel » Mon Oct 02, 2006 3:28 pm

This is a (non-optimized) solution in Maria's style. I post it to point out the difference in difficulty to the puzzles on top of my hardest list:
After basic steps:
1. g3=3, h17=27, h3=1, h4=6, b3=7, a5=7, k4=7, df2=16, d1=7, f1=3, h7=7, g2=7, g7=2, e3=2, c4=2, a6=1, b6=4, b4=8, a2=2, a9=8, b9=1, d8=4, e4=1, *g4=5*, e1=4, d8=4, f8=1, f7=9, b7=5, b1=8, a1=5, b9=1, a8=9, *g8=5*, contradiction
Singles from here.
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