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Impossible Menneske No. 04

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keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Sun Mar 03, 2013 5:09 pm Post subject: Impossible Menneske No. 04

Code:

M6912021 Impossible (4283)
+-------+-------+-------+
| . . . | 7 . . | . . . |
| . . 1 | . 3 . | . . 2 |
| 5 . . | . . 6 | . . 1 |
+-------+-------+-------+
| . 9 . | . . 7 | 4 . . |
| . 1 3 | . . . | 7 2 . |
| . . 6 | . . . | . . . |
+-------+-------+-------+
| . 4 . | 3 6 . | . . 9 |
| . . 2 | . . . | . . . |
| . . . | . . 4 | . 5 . |
+-------+-------+-------+

Play this puzzle online at the Daily Sudoku site

Keith

Last edited by keith on Sun Mar 17, 2013 4:31 am; edited 1 time in total

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Sun Mar 03, 2013 5:25 pm Post subject:

I usually play all your posted puzzles, but have to draw the line at this series.

keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Sun Mar 03, 2013 6:31 pm Post subject:

Marty R. wrote:

I usually play all your posted puzzles, but have to draw the line at this series. Embarassed

I don't do these either, at least not in an armchair with pencil and paper! When I pick Menneskes, they are generally below 30. oaxen asked for really tough puzzles to discuss ...

Keith

Marty R.

Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA

Posted: Sun Mar 03, 2013 6:55 pm Post subject:

Quote:

oaxen asked for really tough puzzles to discuss ...

He got his wish. I tried the first two and it seemed fruitless to try more.

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Sun Mar 03, 2013 8:56 pm Post subject:

#1. r6c6=3;r56c1=4,r12c8=7=r7c13,r6c78=9; UP23
#2. Chain[3] : L2-Wing : 5r4c3=(5-7)r6c2=7r6c1-7r7c1=7r7c3 :=> -5r7c3;UP42;r89c7=6=r1c89,r2c12=67,r4c15=28,r9c345=289
#3. Chain[2] : EmptyRectangles on 8,9 : r3c3=r9c3-r9c45=r8c4 :=> -89r3c4;r3c4=4;r56c5=45
#4. Chain[8] : r9c3=9 or r1c1=9->contradiction :=> r9c3=8;UP81
Interpretation :

Code:

+------------------+-----------------+--------------------+
| 8-9(3) (38) 4 | 7 1 2 | 589 68(9) 568 |
| 67 67 1 | 5 3 89 | 89 4 2 |
| 5 2 89 | 4 89 6 | 3 7 1 |
+------------------+-----------------+--------------------+
| 2(8) 9 5 | 16 (28) 7 | 4 16 3 |
| 48 1 3 | 689 45 89 | 7 2 568 |
| 2478 7(8) 6 | 8(12) 45 3 | 589(1) 8(19) 58 |
+------------------+-----------------+--------------------+
| 18 4 7 | 3 6 5 | 2 18 9 |
| 689 5 2 | 89 7 1 | 68 3 4 |
| 6(13) 6(3) 89 | 289 289 4 | 6(1) 5 7 |
+------------------+-----------------+--------------------+

Chain[8] : Kraken Row 1R6 -> 3r1c1=9r1c8 :=> -9r1c1

(1-2)r6c4=(2-8)r4c5=8r4c1-8r6c2=(8-3)r1c2=3r1c1
||
1r6c7-1r9c7=(1-3)r9c1=3r1c1
||
(1-9)r6c8=9r1c8

or
#4. Chain[3] : X-Loop on 8 : r4c1=r4c5-r3c5=r3c3-r1c2=r6c2 @ :=> -8r9c5.r156c1;r89c4=8
#5. Chain[2] : Skyscraper on 8 : r2c7=r2c6-r5c6=r5c9 :=> -8r1c9.r6c7;r56c9=8
#6. Chain[3] : S-Wing : 5r1c7=5r1c9-(5=8)r6c9-8r6c2=8r1c2 :=> -8r1c7
#7. Chain[4] : XY-Chain : (8=3)r1c2-(3=6)r9c2-(6=1)r9c7-(1=8)r7c8 :=> -8r1c8;UP81

[edit : correction of 2 typos]

Last edited by JC Van Hay on Tue Mar 05, 2013 7:03 am; edited 1 time in total

oaxen

Joined: 10 Jul 2006
Posts: 96

Posted: Mon Mar 04, 2013 10:04 am Post subject:

keith wrote:

Marty R. wrote:

I usually play all your posted puzzles, but have to draw the line at this series. Embarassed

I don't do these either, at least not in an armchair with pencil and paper! When I pick Menneskes, they are generally below 30. oaxen asked for really tough puzzles to discuss ...

Keith

And I am very happy you took the job to transfer them here. This time I failed so I have to ask my butler to print a new copy and recapitulate the pencilmarks. Then for sure I will enjoy it in my armchair.
Make a new try Marty! Find the promising bivalues and step after step you will be successful.

DonM

Joined: 15 Sep 2009
Posts: 51

Posted: Tue Mar 05, 2013 2:30 am Post subject:

Menneske Impossible 4 (ER=7.1) post SSTS (Simple Sudoku Technique Set):

Code:

1. (7)r7c3=r7c1-r6c1=(7-5)r6c2=(5)r7c2 => -5r7c3 -> many singles

Code:

*--------------------------------------------------------------------*
| 3689 368 4 | 7 1 2 | 5689 689 568 |
| 6789 678 1 | 5 3 89 | 689 4 2 |
| 5 2 89 | 489 489 6 | 3 7 1 |
|----------------------+----------------------+----------------------|
| 28 9 5 | 1268 28 7 | 4 168 3 |
| 48 1 3 | 4689 4589 89 | 7 2 568 |
| 2478 78 6 | 1248 2458 3 | 1589 189 58 |
|----------------------+----------------------+----------------------|
| 18 4 7 | 3 6 5 | 2 18 9 |
| 689 5 2 | 89 7 1 | 68 3 4 |
| 13689 368 89 | 289 289 4 | 168 5 7 |
*--------------------------------------------------------------------*

2. SIS aur(36)r19c12[(6)r8c1=(6)r2c12]
(8)r3c3=r9c3-grp(8)r9c45=(8-9)r8c4=(9)r8c1-[(6)r8c1=(6)r2c12]-als(6=89)r2c67 => -8r2c12 -> (lc) -8r1c789
stte

This is one of those 'sheep in wolve's clothing' puzzles. Even after SSTS, there are still only 23 givens, but it largely crumbles after the first chain. There are many alternates to step #2, but the above was the only one I could find that totally finished it off without more basic methods being necessary.

Fun puzzle!

keith

Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA

Posted: Tue Mar 05, 2013 6:53 am Post subject:

Quote:

Fun puzzle!

To each his own.

I hear oaxen's butler has been brewing many cups of tea!

Keith Very Happy

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Tue Mar 05, 2013 7:50 am Post subject:

DonM wrote:

2. SIS aur(36)r19c12[(6)r8c1=(6)r2c12] ... => -8r2c12 -> (lc) -8r1c789 stte

-8r2c12 is contained in the follow-on of step 1 (r89c7=6=r1c89,r2c12=67)!
But it doesn't imply -8r1c789 because of 8r3c3!

Nevertheless, +8r2c7 can be proved using a chain[7] after application of LS and LC from step 1.

Code:

+-----------------+----------------+---------------------+
| 8(39) (38) 4 | 7 1 2 | 58(9) 68(9) 568 |
| 67 67 1 | 5 3 89 | 8-9 4 2 |
| 5 2 89 | 489 489 6 | 3 7 1 |
+-----------------+----------------+---------------------+
| 28 9 5 | 16 28 7 | 4 16 3 |
| 48 1 3 | 4689 4589 89 | 7 2 568 |
| 2478 7(8) 6 | 1248 2458 3 | (1589) 189 (58) |
+-----------------+----------------+---------------------+
| 18 4 7 | 3 6 5 | 2 18 9 |
| 689 5 2 | 89 7 1 | 68 3 4 |
| 6(13) 6(3) 89 | 289 289 4 | 6(1) 5 7 |
+-----------------+----------------+---------------------+

Chain[7] : 9r1c78=(9-3)r1c1=3r1c2-[3r9c2=(3-1)r9c1=1r9c7 and 8r1c2=58r6c29]-(158=9)r6c7 :=> -9r2c7;ste

arkietech

Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

Posted: Thu Mar 07, 2013 4:18 am Post subject:

I have been wanting to get into nets. Comments, help and advice welcomed.

Code:

*-----------------------------------------------------------------------------*
| 23689 2368 489 | 7 124589 12589 | 35689 34689 34568 |
| 6789 678 1 | 4589 3 589 | 5689 46789 2 |
| 5 2378 4789 | 2489 2489 6 | 389 34789 1 |
|-------------------------+-------------------------+-------------------------|
| 28 9 58 | 12568 1258 7 | 4 1368 3568 |
| 48 1 3 | 45689 4589 589 | 7 2 568 |
| 2478 2578 6 | 12458 12458 3 | 1589 189 58 |
|-------------------------+-------------------------+-------------------------|
| 178 4 578 | 3 6 1258 | 128 18 9 |
| 13689 3568 2 | 1589 15789 1589 | 1368 13468 34678 |
| 13689 368 89 | 1289 12789 4 | 12368 5 3678 |
*-----------------------------------------------------------------------------*
net
7r3c3 7r6c2 5r4c3
7r7c3 5r4c3
5r4c3;

*-----------------------------------------------------------*
| 38-9 38 4 | 7 1 2 | 589 689 568 |
| 67 67 1 | 5 3 89 | 89 4 2 |
| 5 2 89 | 489 489 6 | 3 7 1 |
|-------------------+-------------------+-------------------|
| 28 9 5 | 16 28 7 | 4 16 3 |
| 48 1 3 | 4689 4589 89 | 7 2 568 |
| 2478 78 6 | 1248 2458 3 | 1589 189 58 |
|-------------------+-------------------+-------------------|
| 18 4 7 | 3 6 5 | 2 18 9 |
| 689 5 2 | 89 7 1 | 68 3 4 |
| 136 36 89 | 289 289 4 | 16 5 7 |
*-----------------------------------------------------------*
net
9r1c1 8r3c3 8r6c2 8r4c5 8r9c4 8r2c6 8r8c7 1r7c8 1r9c1 -3r9c1
9r1c1 -3r1c1
contradiction -9r1c1; ste

DonM

Joined: 15 Sep 2009
Posts: 51

Posted: Sat Mar 09, 2013 7:25 am Post subject:

JC Van Hay wrote:

DonM wrote:

2. SIS aur(36)r19c12[(6)r8c1=(6)r2c12] ... => -8r2c12 -> (lc) -8r1c789 stte

-8r2c12 is contained in the follow-on of step 1 (r89c7=6=r1c89,r2c12=67)!
But it doesn't imply -8r1c789 because of 8r3c3!

Yes, another reason why I shouldn't do any solving after 10pm- that 8r3c3 (that prevents the locked candidates) couldn't be more obvious! Anyway, here is my revised solution. I was particularly interested in finding something that avoided other basic methods or all the various locked sets/candidates that seemed to follow what looked like good eliminations:

Menneske Impossible 4 (ER=7.1) post SSTS (Simple Sudoku Technique Set):

Code:

1. (7)r7c3=r7c1-r6c1=(7-5)r6c2=(5)r7c2 => -5r7c3 -> many singles
2. als(1=68)r89c7-(68=9)r2c7-grp(9)r1c78=(9-3)r1c1=(3)r9c1 => -1r9c1 => several singles
3. aur(58)r16c79[(8)r2c7=(8)r5c9]-(6)r5c9=r4c8-(6=9)r1c8 => r2c7<>9=8
stte

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