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 

Set Keith_1 Puzzle 2

 
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj
View previous topic :: View next topic  
Author Message
daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Tue Jan 20, 2009 2:10 am    Post subject: Set Keith_1 Puzzle 2 Reply with quote

My first attempt to purposely generate VH+AE puzzles (as suggested by Keith) has produced some interesting failures. Here's one.

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

Play this puzzle online at the Daily Sudoku site

===== ===== ===== ===== ===== ===== ===== ===== ===== ===== ===== ===== =====

Can be solved using steps from ...

Basics: Naked/Hidden Single, Naked Pair/Triple, Locked Candidate 1/2

Basics+: Naked Quad, Hidden Pair/Triple/Quad

VH: BUG+1, Remote Pair, UR Type 1, X-Wing, XY-Wing

Advanced: 2-String Kite, Empty Rectangle, Skyscraper, UR Type 2, XYZ-Wing

Extreme: finned X-Wing, Multiple Colors, M-Wing, W-Wing, XY-Chain

VH+AE: multi-step VH plus one Advanced and/or one Extreme step.

Extreme+: Swordfish, Jellyfish, (but mostly) Chain
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Tue Jan 20, 2009 4:24 am    Post subject: Re: Set Keith_1 Puzzle 2 Reply with quote

daj95376 wrote:
My first attempt to purposely generate VH+AE puzzles (as suggested by Keith) has produced some interesting failures. Here's one.

OMG! They're naming puzzles for me.Embarassed

At first glance, this can be solved with two of my four-cell extended XY-wings. It is not a "failure".

I will only be able to kick back with pencil and paper and a cup of coffee to really figure this one out later on Tuesday.

Keith
Back to top
View user's profile Send private message
Marty R.



Joined: 12 Feb 2006
Posts: 5166
Location: Rochester, NY, USA

PostPosted: Tue Jan 20, 2009 5:14 am    Post subject: Reply with quote

Either I made a lucky error or else this didn't require a VH + AE, but it was a one -stepper.

Quote:
W-Wing on 58
Back to top
View user's profile Send private message
keith



Joined: 19 Sep 2005
Posts: 3179
Location: near Detroit, Michigan, USA

PostPosted: Tue Jan 20, 2009 11:23 pm    Post subject: Reply with quote

After basics:
Code:
+-------------+-------------+-------------+
| 3   9   7   | 2   4   6   | 5   8   1   |
| 6   5   4   | 8   1   79  | 29  279 3   |
| 8   2   1   | 5   3   79  | 6   4   79  |
+-------------+-------------+-------------+
| 7   4   2   | 9   6   3   | 1   5   8   |
| 5   1   3   | 7   8   2   | 4   69  69a |
| 9   68  68  | 4   5   1   | 7   3   2   |
+-------------+-------------+-------------+
| 4   68d 9   | 1   2   58  | 3   67 5-67 |
| 2   3   58c | 6   7   4   | 89  1   59b |
| 1   7   568 | 3   9   58  | 28  26  4   |
+-------------+-------------+-------------+

Marty is correct: A W-wing takes out <5> in R9C3, solving the puzzle.

Also, abcd is a 4-cell chain with pincers <6>. This leads to another 4-cell chain that takes out <5> in R8C9. Or, it leads to a BUG+1.

Keith
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Wed Jan 21, 2009 12:32 am    Post subject: Re: Set Keith_1 Puzzle 2 Reply with quote

daj95376 wrote:
My first attempt to purposely generate VH+AE puzzles (as suggested by Keith) has produced some interesting failures. Here's one.

After basics, there are:

2x 5-cell XY-Chain that crack the puzzle
2x W-Wing that crack the puzzle
2x M-Wing that crack the puzzle

It also appears to be a BUG+3.

I thought it was interesting that so few remaining candidates were this difficult to resolve.
Back to top
View user's profile Send private message
tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Wed Jan 21, 2009 1:44 pm    Post subject: Reply with quote

Another one-step solution is a "funny" version of Keiths' 4-cell extended xy-wing.
Code:

+-------------+-------------+-------------+
| 3   9   7   | 2   4   6   | 5   8   1   |
| 6   5   4   | 8   1   79  | 29  279 3   |
| 8   2   1   | 5   3   79  | 6   4   79  |
+-------------+-------------+-------------+
| 7   4   2   | 9   6   3   | 1   5   8   |
| 5   1   3   | 7   8   2   | 4   69  69a |
| 9   68  68  | 4   5   1   | 7   3   2   |
+-------------+-------------+-------------+
| 4   68a 9   | 1   2   58  | 3   67d 567c|
| 2   3   58b | 6   7   4   | 89  1   -59e|
| 1   7   568 | 3   9   58  | 28  26  4   |
+-------------+-------------+-------------+


Looking at the xy-wing a, b, and pseudo-cell c-d,
If pivot a = <8>, then b = <5>
If pivot a = <6>, then c-d = <5>
This deletes the <5> at e to solve the puzzle

Ted
Back to top
View user's profile Send private message
cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Wed Jan 21, 2009 7:05 pm    Post subject: Reply with quote

Quote:
Marty is correct: A W-wing takes out <5> in R9C3, solving the puzzle.

I am an expert on w-wings (have been for a fortnight now). I agree with Marty that there is an w-wing on <58> but surely this removes the <8> from R7C2.
Back to top
View user's profile Send private message
daj95376



Joined: 23 Aug 2008
Posts: 3855

PostPosted: Wed Jan 21, 2009 9:47 pm    Post subject: Reply with quote

This puzzle is a good example for why short explanations don't always get the job done. Ignore the abbreviated notation from my solver and just examine the results. All of these crack the puzzle open after basics.

Code:
 -5r8c3  8r8c3  9r8c7  2r2c7  8r9c7  5r9c6  [XY-Chain] <> 5 [r9c3]
 -6r7c2  8r7c2  5r7c6  8r9c6  2r9c7  6r9c8  [XY-Chain] <> 6 [r7c89],[r9c3]

 -5r8c3  8r8c3  8r7c6  5r7c9                [M-Wing  ] <> 5 [r8c9]
 -8r9c6  5r9c6  5r8c3  8r8c7                [M-Wing  ] <> 8 [r9c7]

 -5r8c3  8r8c3  8r7c6  5r9c6                [W-Wing  ] <> 5 [r9c3]
 -8r7c6  5r7c6  5r8c9  8r8c3                [W-Wing  ] <> 8 [r7c2]
Back to top
View user's profile Send private message
wapati



Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.

PostPosted: Wed Jan 21, 2009 10:01 pm    Post subject: Reply with quote

cgordon wrote:
Quote:
Marty is correct: A W-wing takes out <5> in R9C3, solving the puzzle.

I am an expert on w-wings (have been for a fortnight now). I agree with Marty that there is an w-wing on <58> but surely this removes the <8> from R7C2.


I have tried to agree. I cannot. What is your W-wing?
Back to top
View user's profile Send private message
cgordon



Joined: 04 May 2007
Posts: 769
Location: ontario, canada

PostPosted: Wed Jan 21, 2009 10:19 pm    Post subject: Reply with quote

Quote:
I have tried to agree. I cannot. What is your W-wing?

Cut me some slack here because I am only a recent expert. Looking at Ted's grid there are only two <5>s in C9. So there has to be an <8> in one of the <58> pairs in R78. So any <8> that sees both pairs has to go. Isn't that a w-wing - if not I want it called a CG wing!

Code:
            
+-------+-------+--------+   
| . . . | . . . | . .  . |   
| . . . | . . . | . .  . |   
| . . . | . . . | . .  . |   
+-------+-------+--------+   
| . . . | . . . | . .  . |   
| . . . | . . . | . .  . |   
| . . . | . . . | . .  . |   
+-------+-------+--------+   
| .68 . | . . 58| . . 567|   
| . . 58| . . . | . . 59 |   
| . . . | . . . | . . .  |
+-------+-------+--------+
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    dailysudoku.com Forum Index -> Puzzles by daj 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