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 

March 18 VH
Goto page Previous  1, 2
 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles
View previous topic :: View next topic  
Author Message
Victor



Joined: 29 Sep 2005
Posts: 207
Location: NI
PostPosted: Thu Mar 20, 2008 10:49 am    Post subject: Reply with quote
Craig wrote:
Quote:
the creators should have stopped at Type 5

I do agree that this kind of UR is weird. But I don't see that you can ban this kind without banning them all (which I believe some people do, which is fair enough).
[I like URs in general because (a) they sometimes solve puzzles that other methods don't seem to touch and (b) they can produce neat logic. I jokingly suggested a style judge once. No prizes for this VH, which produced nothing really interesting. But in the previous one Marty was the definite winner (having screwed up 1st time round!) - an elegant little bit of logic that depended on UR thinking. No UR = no nice logic here.]
Back to top
View user's profile Send private message
ravel



Joined: 21 Apr 2006
Posts: 536
PostPosted: Thu Mar 20, 2008 6:51 pm    Post subject: Reply with quote
Earl wrote:
The HINT on Draw/Play says that the next move in this grid is 8 in R2C5.

Why?
Code:
+------------+-----------+------------+
| 5 48  469  | 1  7  246 | 269 68 3   |
| 3 1   69   | 26 89 5   | 4   7  268 |
| 2 478 4679 | 3  89 46  | 569 1  568 |
+------------+-----------+------------+
| 9 3   1    | 4  26 8   | 57  26 57  |
| 7 6   2    | 5  1  3   | 8   9  4   |
| 8 45  45   | 9  26 7   | 1   3  26  |
+------------+-----------+------------+
| 1 2   37   | 68 5  9   | 367 4  678 |
| 4 9   8    | 7  3  26  | 26  5  1   |
| 6 57  357  | 28 4  1   | 37  28 9   |
+------------+-----------+------------+

I suppose the program did, what most here did - x-wing [Edit typo:] r1c8<>2 (already done in this grid), xy-wing r13c7<>6, locked candidate box 9 r7c9<>6, xyz-wing r3c9<>6, triple 578 in column 9 r2c9<>8. So the next number after this long way is r2c5=8.
Btw. i missed something and solved it with a chain similar to George's one ...


cgordon wrote:

Code:
               
+-------+-------+------+   
| . . 7 | . . . | 3 . .|   
| . . . | . . . | . . .|   
| . . 3 | . . . | 7 . .|
+-------+-------+------+


What's Deadly about that?? There aren't two options (I don't think)
.
I can understand your doubts. Nataraj already explained it, but maybe it helps to say it in other words again, because it needs a bit theory understanding.

Suppose you have such a pattern, it leads to a solution and (important) none of the 4 numbers was a given. Then in this solution there cannot be a 3 or 7 in the same rows, columns or boxes. So you can xx the 2 numbers (none was given) and you get a second solution.

So any assumption that leads to this pattern must be false, in the example case the assumption that the x-wing number is in the 3 value-cell.

Last edited by ravel on Sat Mar 22, 2008 9:15 am; edited 1 time in total
Back to top
View user's profile Send private message
storm_norm



Joined: 18 Oct 2007
Posts: 1741
PostPosted: Thu Mar 20, 2008 8:27 pm    Post subject: Reply with quote
Quote:
tsk tsk, I am away for a day, and look what happens!


Keith,
being gone for a day warrants a tsk tsk??

so you get a tsk tsk for being gone for a day.

what kind reaction do you have for the amount of time since samgj has posted in the "daily sudoku puzzle" thread?

I guess I am curious as to the lay off?
Back to top
View user's profile Send private message
nataraj



Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
PostPosted: Thu Mar 20, 2008 8:58 pm    Post subject: Reply with quote
storm_norm wrote:
what kind reaction do you have for the amount of time since samgj has posted in the "daily sudoku puzzle" thread?


Hm. That would be 242*2=484 "tsk"s. Easy question.
Laughing Laughing Laughing
Back to top
View user's profile Send private message Send e-mail Visit poster's website
crunched



Joined: 05 Feb 2008
Posts: 168
PostPosted: Sat Mar 22, 2008 3:04 am    Post subject: Reply with quote
Please excuse my simpleton level, but I do not understand where there is an x-wing on 2. Could somebody please point that out?
Back to top
View user's profile Send private message
ravel



Joined: 21 Apr 2006
Posts: 536
PostPosted: Sat Mar 22, 2008 9:12 am    Post subject: Reply with quote
Sorry, this was my fault. I had copied Earl's grid, where the 2 in r1c8 already was eliminated. This was the x-wing i had in mind. Of course you cannot eliminate 2 in r1c7. Here is Victors grid:
Code:
+------------+-----------+-------------+
| 5 48  469  | 1  7 *246 |*269 268 3   |
| 3 1   69   | 26 89 5   | 4   7   268 |
| 2 478 4679 | 3  89 46  | 569 1   568 |
+------------+-----------+-------------+
| 9 3   1    | 4  26 8   | 57  26  57  |
| 7 6   2    | 5  1  3   | 8   9   4   |
| 8 45  45   | 9  26 7   | 1   3   26  |
+------------+-----------+-------------+
| 1 2   37   | 68 5  9   | 367 4   678 |
| 4 9   8    | 7  3 *26  |*26  5   1   |
| 6 57  357  | 28 4  1   | 37  28  9   |
+------------+-----------+-------------+
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Daily Sudoku puzzles All times are GMT
Goto page Previous  1, 2
Page 2 of 2

 
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