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Menneske6905337

 
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Sun Nov 11, 2012 11:35 am    Post subject: Menneske6905337 Reply with quote

Code:

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

Play this puzzle online at the Daily Sudoku site

(I'm posting a puzzle simply because no one else has. Is it preferred that they should be as published, or after 'basics'?
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Sun Nov 11, 2012 4:19 pm    Post subject: Reply with quote

Quote:

(I'm posting a puzzle simply because no one else has. Is it preferred that they should be as published, or after 'basics'?


Just post the original if your purpose is to offer a puzzle for others to play. If you're playing a puzzle and are stuck, you'd post the grid at the point you're stuck.
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Clement



Joined: 24 Apr 2006
Posts: 656
Location: Dar es Salaam Tanzania

PostPosted: Sun Nov 11, 2012 5:58 pm    Post subject: Menneske6905337 Reply with quote

They should be as publihed.
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TNova



Joined: 17 Jul 2012
Posts: 16
Location: Bromley, UK

PostPosted: Mon Nov 12, 2012 12:10 pm    Post subject: Menneske6905337 Reply with quote

Hi Ffred,

Thanks for posting these puzzles, but this one has 210 solutions! Can you please recheck.

Tim
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Clement



Joined: 24 Apr 2006
Posts: 656
Location: Dar es Salaam Tanzania

PostPosted: Mon Nov 12, 2012 12:18 pm    Post subject: Menneske 6905337 Reply with quote

The original puzzle is like this
Code:

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

Play this puzzle online
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Mon Nov 12, 2012 7:32 pm    Post subject: Re: Menneske6905337 Reply with quote

TNova wrote:
Hi Ffred,

Thanks for posting these puzzles, but this one has 210 solutions! Can you please recheck.

Tim


I couldn't even find one of the 210!!
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Tue Nov 13, 2012 12:45 am    Post subject: Reply with quote

Ffred,

Maybe next time you could select a puzzle more in line with our talents? Very Happy

Showing puzzle number: 6905337
Puzzletype: Optimal Sudoku
Startnumbers: 24
Difficulty: Impossible (3389)
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Tue Nov 13, 2012 9:46 am    Post subject: Reply with quote

Many apologies for the mistakes. I was copying from my 'post-basic' sheet & (a) forgot that a couple of 4s had been filled in (b) very carelessly left out a 3. (I promise that if I post again I'll be super careful, having absorbed the lesson that it pays not to work needlessly fast.)

Sorry Marty. I thought that this was about right based on the sorts of puzzles I've seen posted - harder than some, easier than others. (I've done dozens, maybe hundreds of these Menneske Impossibles. A few turned out to be too easy - e.g. just one XY-wing needed. A few turned out to be too difficult for me. Most, like this one, are somewhere in between.)

Here's the position after basics:-
Code:

+------------------+-------------------+-------------------+
| 12369 12369 236  | 15679 8     12579 | 13    4      2567 |
| 1268b 5     268a | 3     4     127c  | 9     267    267  |
| 7     12369 4    | 1569  129   1259  | 13    2568   2568 |
+------------------+-------------------+-------------------+
| 13458 137   378  | 2     6     1479  | 458   589    589  |
| 12468 126   9    | 18e   5     14d   | 7     3      268  |
| 24568 267   2678 | 789f  79    3     | 24568 25689  1    |
+------------------+-------------------+-------------------+
| 239   8     237  | 1579  12379 6     | 25    2579   4    |
| 2369  23679 5    | 4     2379  8     | 26    1      2679 |
| 269   4     1    | 579   279   2579  | 2568  256789 3    |
+------------------+-------------------+-------------------+

Play this puzzle online at the Daily Sudoku site

I've marked one possible move 1:
8r2c3 = (8-1)r2c1 = r2c6 - r5c6 = (1-8)r5c4 = r6c4. r6c3 <> 8

For a second (and final) move, look at the two 267s, r6c23 and what would happen in box 4/r5 if they were any of the 3 possible pairs. You could explain using ALSs but really there's no prior knowledge needed.


Last edited by ffred on Tue Nov 13, 2012 11:33 am; edited 1 time in total
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ffred



Joined: 29 Oct 2012
Posts: 19
Location: Kent, Egland

PostPosted: Tue Nov 13, 2012 10:14 am    Post subject: Reply with quote

PS 1. Hi Tim, thanks for pointing out the mistake. I see that you too use Andrew Stuart's excellent program! (It's maybe a bit lazy, but I often use it to dash through the basics, print out that sheet and work from there. I still like doing basics-only sudokus once a week in my Sunday paper. The Hard just needs you to spot a hidden pair or something like that - fun to do without writing in candidates. But it seems a waste of time when I'm doing a difficult puzzle.)

PS 2. Marty, you were one of my heros/gurus about 5 yrs ago: I learnt how to make deductions about URs etc. from your posts. So it seems very strange to be offering advice: I hope that you're not offended. Here goes. Before I was really comfortable with Eureka I used to mark an F for false under the starting candidate, the 8 in r2c3 in the grid above. That fixes the 8 in r2c1 as a T for true, and you can therefore put an F under the 1 in that cell. That makes the 1 in r2c6 a T. And so on. You end up with a the 8 in r6c4 being a T. Then it's easy to translate into Eureka. Going from F to T is a strong link, an =. Going from T to F is a weak link, a -.
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SudoQ



Joined: 02 Aug 2011
Posts: 127

PostPosted: Tue Nov 13, 2012 10:15 am    Post subject: Reply with quote

Code:
r2c1=8 -> r2c6=1 -> r5c4=1 -> r5c9=8 -> 
       ->                  -> r6c4=8 -> r6c23=7 => r2c1<>8
/SudoQ
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Tue Nov 13, 2012 3:52 pm    Post subject: Reply with quote

[quote="SudoQ"][code]r2c1=8 -> r2c6=1 -> r5c4=1 -> r5c9=8 ->
-> -> r6c4=8 -> r6c23=7 => r2c1<8> r5c9=8. What I'm seeing superficially is that r5c4=1 -> a 268 triple in r5.

Thanks.
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Tue Nov 13, 2012 3:53 pm    Post subject: Reply with quote

Quote:
I hope that you're not offended.


Not offended at all.
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keith



Joined: 19 Sep 2005
Posts: 3150
Location: near Detroit, Michigan, USA

PostPosted: Tue Nov 13, 2012 6:39 pm    Post subject: Reply with quote

Quote:
Many apologies for the mistakes. I was copying from my 'post-basic' sheet & (a) forgot that a couple of 4s had been filled in (b) very carelessly left out a 3. (I promise that if I post again I'll be super careful, having absorbed the lesson that it pays not to work needlessly fast.)

Sorry Marty. I thought that this was about right based on the sorts of puzzles I've seen posted - harder than some, easier than others. (I've done dozens, maybe hundreds of these Menneske Impossibles. A few turned out to be too easy - e.g. just one XY-wing needed. A few turned out to be too difficult for me. Most, like this one, are somewhere in between.)

Ffred: You can copy and past Menneske puzzles into Nataraj' format tool, that will eliminate mistakes in transcribing them.

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?p=16010

Then, from Draw/Play, use ASCII to cut and paste the puzzle into the forum.

Menneske puzzles have a difficulty rating in parentheses (). The higher the rating, the more difficult the puzzle. For my own enjoyment, I usually print out those that are rated from 10 to 20. Interesting ones that admit multiple solution paths are below about 80. Above 100, you're getting to where there are no pattern solutions, just chains.

Though I have my theory, no one knows how the rating is computed.

Keith
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SudoQ



Joined: 02 Aug 2011
Posts: 127

PostPosted: Tue Nov 13, 2012 10:43 pm    Post subject: Reply with quote

Marty R. wrote:
What I'm seeing superficially is that r5c4=1 -> a 268 triple in r5.

Code:
Since r5c1<>8, r5c9=8 -> a 26 pair in r5c12.
/SudoQ
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Marty R.



Joined: 12 Feb 2006
Posts: 5123
Location: Rochester, NY, USA

PostPosted: Wed Nov 14, 2012 1:20 am    Post subject: Reply with quote

Thanks. It's the rule, not the exception, that I miss that kind of stuff. Embarassed
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