Extreme Puzzle No.6

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Extreme Puzzle No.6

Postby yzfwsf » Fri Jan 01, 2021 10:32 am

Code: Select all
.4.1..9....5..8.1.....2.8.5.1.8..3.............3..6.9.2.6.5.....9.6..2....1..9.7.

Merry new year to all.
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Re: Extreme Puzzle No.6

Postby urhegyi » Fri Jan 01, 2021 7:52 pm

Or thisone which is essentially the same:
Code: Select all
.4.1..9....2..8.1.....3.8.2.1.8..5.............5..6.9.3.6.2.....9.6..3....1..9.7.
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Re: Extreme Puzzle No.6

Postby m_b_metcalf » Fri Jan 01, 2021 8:12 pm

urhegyi wrote:Or thisone which is essentially the same:
Code: Select all
.4.1..9....2..8.1.....3.8.2.1.8..5.............5..6.9.3.6.2.....9.6..3....1..9.7.

It is exactly the same, a renumbered isomorph.
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Re: Extreme Puzzle No.6

Postby Cenoman » Sat Jan 02, 2021 5:46 pm

Code: Select all
.4.|1..|9..
..5|..8|.1.
...|.2.|8.5
---+---+---
.1.|8..|3..
...|...|...
..3|..6|.9.
---+---+---
2.6|.5.|...
.9.|6..|2..
..1|..9|.7.

My usual map of givens per box:
Code: Select all
| 2 | 3 | 4 |
| 2 | 2 | 2 |
| 4 | 3 | 2 |

This suggests central or diagonal symmetry. Diagonal symmetries are not possible (4 digits an the main diagonal; 6, 8 on the second diagonal not compatible in boxes [19].
Central symmetry is present on the givens with the digit permutation [19] [25] [3] [47] [68] => +3 r5c5

The puzzle rating is lowered to SE 9.2, still hard to solve.
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Re: Extreme Puzzle No.6

Postby Leren » Sat Jan 02, 2021 7:41 pm

I got the rotational symmetry and solved 7 cells with reasonable chains. After trying all the usual suspects I'm guessing that there might be a Senior Exocet, which I don't do.

Leren

PS I had one more trick up my solver's sleeve. It found an Exocet r5c4 r5c6 r4c3 r6c7 2457 which solves the puzzle, but it required what I call a full digit expansion to prove it, so I am reluctant to use it.

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