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Impossible Menneske No. 10

 
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keith



Joined: 19 Sep 2005
Posts: 3175
Location: near Detroit, Michigan, USA

PostPosted: Fri Mar 22, 2013 12:11 am    Post subject: Impossible Menneske No. 10 Reply with quote

By the Menneske rating, the 3rd hardest so far, after 7 and 6. We shall see.

Code:
 M6912646  Impossible (6211)
+-------+-------+-------+
| . 2 . | . . . | . 9 . |
| . . . | . 7 4 | 8 . . |
| 4 3 . | . . 1 | . . . |
+-------+-------+-------+
| 5 . 6 | 7 . . | . . . |
| . . . | . 2 . | . . . |
| . . . | . . 9 | . . 3 |
+-------+-------+-------+
| . . 3 | . . . | . 8 . |
| . 1 . | 9 5 . | 6 . . |
| . 5 . | . . . | . 7 . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith
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JC Van Hay



Joined: 13 Jun 2010
Posts: 371
Location: Charleroi, Belgium

PostPosted: Fri Mar 22, 2013 3:37 am    Post subject: Reply with quote

#1. USDE; UP24
r5c1=3,r3c5=9
LC(2) :=> -2r79c4.r6c78
[Optional] Finned XWing(3C47) :=> -3r1c56; LC(3) :=> -3r9c4
LC(8 ) :=> -8r56c13

Solving the only strongest digit 3 ...
Code:
+---------------------+------------------------+---------------------------+
| 1678  2      1578   | 568(3)   68(3)  568(3) | 57(134)  9        567(14) |
| 169   69     1(59)  | 6-3(25)  7      4      | 8        36(125)  6(125)  |
| 4     3      578    | 2568     9      1      | 257      256      2567    |
+---------------------+------------------------+---------------------------+
| 5     48(9)  6      | 7        1348   38     | 14(29)   14(2)    148(29) |
| 3     4789   147(9) | 14568    2      568    | 14579    1456     1456789 |
| 127   478    1247   | 14568    1468   9      | 1457     1456     3       |
+---------------------+------------------------+---------------------------+
| 2679  4679   3      | 146      146    267    | 12459    8        12459   |
| 278   1      2478   | 9        5      2378   | 6        234      (24)    |
| 2689  5      248(9) | 1468     13468  2368   | 12349    7        (1249)  |
+---------------------+------------------------+---------------------------+
#2. Chain[10] presented as either an
nrczt-braid[10] written as a Transfer Matrix ...
Code:
3r1c456=3r1c7
        4r1c7=4r1c9
              4r8c9=2r8c9
                    2r2c9=2r2c8[=2r2c4]
                    2r4c9=2r4c8=2r4c7
        1r1c7=1r1c9=======1r2c8=======1r2c9
              4r9c9=2r9c9=============1r9c9=9r9c9
                                9r4c7=======9r4c9=9r4c2
                                            9r9c3=9r5c3=9r2c3
                          5r2c8=======5r2c9=============5r2c3=5r2c4
-> 3r1c456=2r2c4(z-candidate)=5r2c4 :=> -3r2c4; UP36
or, in "English"
r2c4=3->r1c7=3,r1c9=4,r8c9=2=r2c8=r4c7; r2c9=1,r9c9=9=r4c2=r2c3; no 5 in Row 2 :=> -3r2c4; UP36
#3. NP(24)r8c89 + [LC(6) :=> NP(25)r3c78];UP81
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TNova



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

PostPosted: Fri Mar 22, 2013 5:56 pm    Post subject: Reply with quote

I don't know about this puzzle being easier than any of the others in the series. The rating of 11,000+ that Hudoku gave it is - by a long way - the highest difficulty rating that I've ever seen. Previous was about 6,000.

Yes I solved it without using Hodoku's aids, but only after two or three hours of ugly XY chain type eliminations. And I had to trust a NICE loop to really get me on my way. I don't really understand why they always work, but work they do. I must go and read the theory.

I love this type of puzzle though - maybe this could become the board for really nasty puzzles. Thanks to Keith for posting it.

All the best, Tim
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keith



Joined: 19 Sep 2005
Posts: 3175
Location: near Detroit, Michigan, USA

PostPosted: Sat Mar 23, 2013 1:56 am    Post subject: Reply with quote

TNova wrote:
I don't know about this puzzle being easier than any of the others in the series. The rating of 11,000+ that Hudoku gave it is - by a long way - the highest difficulty rating that I've ever seen. Previous was about 6,000.

Yes I solved it without using Hodoku's aids, but only after two or three hours of ugly XY chain type eliminations. And I had to trust a NICE loop to really get me on my way. I don't really understand why they always work, but work they do. I must go and read the theory.

I love this type of puzzle though - maybe this could become the board for really nasty puzzles. Thanks to Keith for posting it.

All the best, Tim

Tim,

Thank you, but I might make a couple of observations:

This is a discussion board, which is what oaxen originally asked for. The value is in the discussion. The success of this forum relies on people posting and discussing solutions.

If anyone wants these puzzles to solve in isolation, just go to Menneske and choose "impossible". They do not need to have them posted here.

I am fascinated by the measures of puzzle "difficulty". Particularly for difficult puzzles they are based on some heuristic, and not on actually solving the puzzle. The variation between measures is interesting, not to mention how well they actually are valid measures. See No. 08!

I also have some idea that puzzles have a personality. I like to solve Menneskes. I have stopped doing puzzles from some other sites, not because they are too difficult, but because I do not like them. Why? I have no idea.

Keith
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TNova



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

PostPosted: Sat Mar 23, 2013 7:25 pm    Post subject: Reply with quote

Hi Keith,

Thank-you for your reply. I guess I'll just stay off the forum if it's only for discussing solutions. I didn't realise that, and I'm sorry to clutter your board. I only came back to Sodoku last year after I retired - to keep my brain active. But although I think I'm still good at solving them I just can't do the sort of notation that was used earlier in this post.

All the best, Tim
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keith



Joined: 19 Sep 2005
Posts: 3175
Location: near Detroit, Michigan, USA

PostPosted: Sat Mar 23, 2013 7:32 pm    Post subject: Reply with quote

Tim,

Not at all. Comments are welcome, even if they do not spell out exactly how you solved the puzzle.

Keith
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TNova



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

PostPosted: Sat Mar 23, 2013 7:59 pm    Post subject: Reply with quote

Hi Keith,

Well I did reply in detail about a solution once, concerning a very difficult puzzle. Look near the end.

http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=6736&highlight=hodoku&sid=fd5a55444742192b0539e730f41c7861

I don't think you'd want many posts like that.

Maybe I'll just try and learn notation, though to me it seems more difficult than the worst Sudoku.

All the best, Tim
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Marty R.



Joined: 12 Feb 2006
Posts: 5162
Location: Rochester, NY, USA

PostPosted: Sat Mar 23, 2013 9:38 pm    Post subject: Reply with quote

Quote:
Maybe I'll just try and learn notation, though to me it seems more difficult than the worst Sudoku.


I was a holdout for years and just started about six months ago. It looks very intimidating but once you learn the basic principles it's not so bad. I had the good fortune of having a mentor who was willing to take the time and trouble and answer all my stupid questions.
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Tue Mar 26, 2013 11:28 am    Post subject: Reply with quote

Ouch!
Code:

#0 SSTS, kite(3) => r9c4<>3

*--------------------------------------------------------------------------------------*
 | 1678     2        1578     | 3568     68       568      | 13457    9        14567    |
 | 169      69       159      | 2356     7        4        | 8        12356    1256     |
 | 4        3        578      | 2568     9        1        | 257      256      2567     |
 |----------------------------+----------------------------+----------------------------|
 | 5        489      6        | 7        1348     38       | 1249     124      12489    |
 | 3        4789     1479     | 14568    2        568      | 14579    1456     1456789  |
 | 127      478      1247     | 14568    1468     9        | 1457     1456     3        |
 |----------------------------+----------------------------+----------------------------|
 | 2679     4679     3        | 146      146      267      | 12459    8        12459    |
 | 278      1        2478     | 9        5        2378     | 6        234      24       |
 | 2689     5        2489     | 1468     13468    2368     | 12349    7        1249     |
 *--------------------------------------------------------------------------------------*

#1 (24=3)r8c98-r2c8=(3-4)r1c7=r1c9*-(4=2)r8c9 => *r79c9<>4, r8c136<>2, r79c79<>2

#2 aahs(67)r35c9 => r1c7<>157,r1c9<>15
   (67)r1c9 - (4)r1c9=r1c7
   ||
   (6)r2c9 - r3c12=(6-78)r1c1=hp(78)r13c3-(78=243)r8c398-(3)r2c8=hp(34)r1c79
   ||
   hp(67)r35c9 - (8)r5c9=r4c9-(8=3)r4c6-r4c5=r9c5-r9c7=r8c8-(3)r2c8=hp(34)r1c79

#3 h-wing (1=2)r2c9-r8c9=(2-3)r8c8=r2c8 => r2c8<>1
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oaxen



Joined: 10 Jul 2006
Posts: 96

PostPosted: Wed Apr 03, 2013 9:15 am    Post subject: Reply with quote

Back again from a short holiday i Morocco. Happy to see that Keith still deliver Menneske to us. In this one bivalues "3" on row 2 are promising. After a short chain it is obvious that it must be R2C8 and that in R1C9 in both cases it is a "1". After that pure basic.
Lars
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