dailysudoku.com Forum Index dailysudoku.com
Discussion of Daily Sudoku puzzles
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

11-25 vanhegan fiendish

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles
View previous topic :: View next topic  
Author Message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Nov 25, 2008 9:53 pm    Post subject: 11-25 vanhegan fiendish Reply with quote

Code:

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

Play this puzzle online at the Daily Sudoku site

Code:
.------------------.------------------.------------------.
| 5     2     4    | 6     1379  179  | 179   8     13   |
| 1     9     38   | 38    5     247  | 47    24    6    |
| 6     37    378  | 238   1239  1249 | 1459  2459  123  |
:------------------+------------------+------------------:
| 2     1     35   | 4     89    59   | 3589  6     7    |
| 9     37    357  | 1     28    6    | 358   235   4    |
| 4     8     6    | 257   279   3    | 159   259   12   |
:------------------+------------------+------------------:
| 7     45    9    | 235   123   125  | 6     34    8    |
| 8     45    2    | 357   6     57   | 34    1     9    |
| 3     6     1    | 9     4     8    | 2     7     5    |
'------------------'------------------'------------------'

two syllables - UGH ! LEE !
Quote:

swordfish on 3; r35c3, r37c4, r5c7 are all not 3.
m-wing {5,7} (5=7)r8c6 - (7)r8c4 = (7-5)r6c4 = (5)r4c6; r7c6 <> 5
this opens up this beast of a chain.
(1=2)r7c6 - (2=5)r7c4 - (5)r6c4 = (5)r4c6 - (5=3)r4c3 - (3)r2c3 = (3)r2c4 - (3)r8c4 = (3)r7c5; r7c5 <> 1


Last edited by storm_norm on Wed Nov 26, 2008 3:27 am; edited 1 time in total
Back to top
View user's profile Send private message
re'born



Joined: 28 Oct 2007
Posts: 80

PostPosted: Tue Nov 25, 2008 10:10 pm    Post subject: Reply with quote

Extend an xyz-wing a little and transport:
Code:

 *-----------------------------------------------------------*
 | 5     2     4     | 6     1379  179   | 179   8     13    |
 | 1     9    +38    |+38    5     247   | 47    24    6     |
 | 6     37    378   | 238   1239  1249  | 1459  2459  123   |
 |-------------------+-------------------+-------------------|
 | 2     1    *35    | 4     89   %59    | 3589  6     7     |
 | 9     37    357   | 1     28    6     | 358   235   4     |
 | 4     8     6     |%257   279   3     | 159   259   12    |
 |-------------------+-------------------+-------------------|
 | 7     45    9     | 23-5  123   125   | 6     34    8     |
 | 8     45    2     |*357   6    *57    | 34    1     9     |
 | 3     6     1     | 9     4     8     | 2     7     5     |
 *-----------------------------------------------------------*

The extended xyz-wing with pivot at r8c4 and pincers at r8c6 and r4c3 implies one of the endpoints is a 5. Transport the 5 from r4c3 to r6c4 via r4c6. This gives the deduction r7c4<>5, cracking the puzzle.
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Tue Nov 25, 2008 10:59 pm    Post subject: Reply with quote

Quote:
This gives the deduction r7c4<>5, cracking the puzzle.

"impressive. most impressive. OBI WAN has taught you well."
its moves like this where you can imagine the puzzle making that cracking sound. like bowling a strike and listening for the pins "crack" as they all fall down.
Back to top
View user's profile Send private message
keith



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

PostPosted: Tue Nov 25, 2008 11:28 pm    Post subject: Reply with quote

re'born,
Quote:
The extended xyz-wing with pivot at r8c4 and pincers at r8c6 and r4c3 implies one of the endpoints is a 5.


I think you should add the strong link on <3> in R2 that extends the wing. If R8C4 is <3>, how do you show that R4C3 is <5>?

35* - 38 = 38 - 357* - 57*

And, I think that one of the * cells is <5>, not one of the endpoints.

(Who was it that was counting the ways to extend a wing?)

Keith
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741

PostPosted: Wed Nov 26, 2008 5:28 am    Post subject: Reply with quote

Code:
.------------------.------------------.------------------.
| 5     2     4    | 6     1379  179  | 179   8     13   |
| 1     9    *38   |*38    5     247  | 47    24    6    |
| 6     37    378  | 238   1239  1249 | 1459  2459  123  |
:------------------+------------------+------------------:
| 2     1    *35   | 4     89   *59   | 3589  6     7    |
| 9     37    357  | 1     28    6    | 358   235   4    |
| 4     8     6    |*257   279   3    | 159   259   12   |
:------------------+------------------+------------------:
| 7    *45    9    |23-5   123   125  | 6     34    8    |
| 8    *45    2    |*357   6    *57   | 34    1     9    |
| 3     6     1    | 9     4     8    | 2     7     5    |
'------------------'------------------'------------------'

could also look like this
(5)r6c4 = (5)r4c6 - (5=3)r4c3 - (3)r2c3 = (3)r2c4 - (3)r8c4 = np(57)r8c46 - (5)r8c2 = (5)r7c2; r7c4 <> 5
Back to top
View user's profile Send private message
nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria

PostPosted: Wed Nov 26, 2008 1:18 pm    Post subject: Reply with quote

I don't find this puzzle ugly at all, at least not if one likes a few challenges.

I'm with Norm through coloring (I'll add a skyscraper (2)) and, before reaching the m-wing, there is a 38 UR type 4 makes r3c34<>3.

Now the m-wing, here: (5)r8c6=r4c6 (via SL (7) col 4); r7c6<>5
Code:

+--------------------------+--------------------------+--------------------------+
| 5       2       4        | 6       1379    179      | 179     8       13       |
| 1       9       38       | 38      5       247      | 47      24      6        |
| 6       37      78       | 28      139     1249     | 1459    2459    123      |
+--------------------------+--------------------------+--------------------------+
| 2       1       35       | 4       89      59*      | 3589    6       7        |
| 9       37      57       | 1       28      6        | 58      235     4        |
| 4       8       6        | 257#    279     3        | 159     259     12       |
+--------------------------+--------------------------+--------------------------+
| 7       45      9        | 25      123     12-5     | 6       34      8        |
| 8       45      2        | 357#    6       57*      | 34      1       9        |
| 3       6       1        | 9       4       8        | 2       7       5        |
+--------------------------+--------------------------+--------------------------+


Thanks to re'born's suggestion a few days ago, I'm trying to make a habit of checking for additional possibilities, when an m-wing begins and ends in the same house (col 6 here) and thus creates a continuous loop.

No 7s can be removed from row 8 or box 8, but
2 can be removed from r6c4.

That leads to this position:

Code:

+--------------------------+--------------------------+--------------------------+
| 5       2       4        | 6       1379    179      | 179     8       13       |
| 1       9       38*      | 38      5       247      | 47      24      6        |
| 6       37      78#      | 28      139     1249     | 1459    2459    123      |
+--------------------------+--------------------------+--------------------------+
| 2       1       35*      | 4       89*     59       | 3589*   6       7        |
| 9       37      57#      | 1       28      6        | 58#     235     4        |
| 4       8       6        | 57      279     3        | 159     259     12       |
+--------------------------+--------------------------+--------------------------+
| 7       45      9        | 25      13      12       | 6       34      8        |
| 8       45      2        | 357     6       57       | 34      1       9        |
| 3       6       1        | 9       4       8        | 2       7       5        |
+--------------------------+--------------------------+--------------------------+


The useless m-wing *:(8)r4c5=r2c3 (via SL 3 in row 4) and
the useless xy-wing #:(8)r3c3=r5c7 (78-57-58)

can be combined (r2c3 sees r3c3):

(8)r4c5=r2c3-r3c3=r5c7; r4c7,r5c5<>8

With r5c5=2 (and 2 gone from r5c7), we have a useless xy-wing (8)r7c2=r5c8 (35-34-45) that can be transported further to give r7c4<>5 and r8c2<>5.

Code:

+--------------------------+--------------------------+--------------------------+
| 5       2       4        | 6       1379    179      | 179     8       13       |
| 1       9       38       | 38      5       247      | 47      24      6        |
| 6       37      78       | 28      139     1249     | 1459    2459    123      |
+--------------------------+--------------------------+--------------------------+
| 2       1       35t      | 4       8       59t      | 359     6       7        |
| 9       37      57t      | 1       2       6        | 8       35*     4        |
| 4       8       6        | 57t2    79      3        | 159     259     12       |
+--------------------------+--------------------------+--------------------------+
| 7       45*     9        | 2-5     13      12       | 6       34*     8        |
| 8       4-5     2        | 357     6       57t1     | 34      1       9        |
| 3       6       1        | 9       4       8        | 2       7       5        |
+--------------------------+--------------------------+--------------------------+


With all the additional diagonal strong links from xy- and other "useless" wings, my diagrams are starting to look very exotic ... :)
Back to top
View user's profile Send private message Send e-mail Visit poster's website
Asellus



Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA

PostPosted: Wed Nov 26, 2008 8:58 pm    Post subject: Reply with quote

storm_norm wrote:
could also look like this
(5)r6c4 = (5)r4c6 - (5=3)r4c3 - (3)r2c3 = (3)r2c4 - (3)r8c4 = np(57)r8c46 - (5)r8c2 = (5)r7c2; r7c4 <> 5

re'born's elimination is more exactly notated this way:
(5)r7c4 - (5)r6c4=(5)r4c6 - (5=3)r4c3 - (3)r2c3=(3)r2c4 - ALS[(3)r8c4=(5)r8c46] - (5)r7c4; r7c4 <> 5

No detour through box 7 is needed.
Back to top
View user's profile Send private message Visit poster's website
re'born



Joined: 28 Oct 2007
Posts: 80

PostPosted: Wed Nov 26, 2008 11:39 pm    Post subject: Reply with quote

keith wrote:
re'born,
Quote:
The extended xyz-wing with pivot at r8c4 and pincers at r8c6 and r4c3 implies one of the endpoints is a 5.


I think you should add the strong link on <3> in R2 that extends the wing. If R8C4 is <3>, how do you show that R4C3 is <5>?


Asellus wrote:

re'born's elimination is more exactly notated this way:
(5)r7c4 - (5)r6c4=(5)r4c6 - (5=3)r4c3 - (3)r2c3=(3)r2c4 - ALS[(3)r8c4=(5)r8c46] - (5)r7c4; r7c4 <> 5


The only difference in the way I thought about it was I didn't rely explicitly on the strong link on 3 in row 2. I followed it like an xy-chain. In my head I was saying "357 sees 57 and 38 which sees 83 which sees 35...okay, xyz-wing on 5."

I find the xy-chain way of extending xyz-wings to be less exhaustive a search, but also less exhausting.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Other puzzles All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group