View previous topic :: View next topic 
Author 
Message 
arkietech
Joined: 31 Jul 2008 Posts: 1752 Location: Northwest Arkansas USA

Posted: Mon Sep 03, 2012 5:14 pm Post subject: Half Mwing 


I am trying to identify what a half mwing is. The following puzzle, identified as a half mwing, located at
http://www.dailysudoku.co.uk/sudoku/forums/viewtopic.php?t=2143
Code: 
++++
 59 45 1  47 6 79  2 3 8 
 7 34 8  5 34 2  1 9 6 
 69 36 2  1 8 39  5 7 4 
++++
 156 156 39  247 34A 8  347B 16 29 
 4 128 39  6 5 137  37 18 29 
 126 1268 7  24 9 13D  34C 168 5 
++++
 3 9 4  8 1 5  6 2 7 
 12 12 5  9 7 6  8 4 3 
 8 7 6  3 2 4  9 5 1 
++++
Either:
1. A is <3>.
Or:
2. A is <4>, C is <4>, D is <3>.
Any cell that sees both A and D cannot be <3>. In particular, we can take out <3> from R5C6.

I tried to put what I see in Eureka and get:
(3=4)r4c5r4c7=(43)r6c7=3r6c6 => 3r5c6
This looks like the classic mwing:
(X=Y)Y=(YX)=X
What am I missing? 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5499 Location: Rochester, NY, USA

Posted: Mon Sep 03, 2012 5:38 pm Post subject: 


Quote:  What am I missing? 
Beats me. I'm no theoretician, but if I played and reported that move I'd call it an MWing. I wonder who'd correct me and say it's just a half. 

Back to top 


keith
Joined: 19 Sep 2005 Posts: 3260 Location: near Detroit, Michigan, USA

Posted: Tue Sep 04, 2012 9:08 am Post subject: 


The original Mwing was built on the idea of a complementary pair:
Two cells, each XY, have the same solution, X or Y. Let's say it is X. Then, on either end you can add a strong link in Y:
XY ..... XY = Y or Y = XY ..... XY
and the end cells are pincers on Y.
The half Mwing does not need a complementary pair. All it needs is the following:
XY ..... aXY
where X in the first cell forces X in the cell containing aXY where a is any other candidates. Then you can add the strong link on Y:
XY ..... aXY = Y
and the end cells are pincers on Y.
It's a "half" wing because it only works one way. There is no requirement that X in aXY has any implication for the cell XY.
Over time, we've forgotten the distinction.
Keith 

Back to top 


arkietech
Joined: 31 Jul 2008 Posts: 1752 Location: Northwest Arkansas USA

Posted: Tue Sep 04, 2012 11:33 am Post subject: 


keith wrote:  The original Mwing was built on the idea of a complementary pair:
Two cells, each XY, have the same solution, X or Y. Let's say it is X. Then, on either end you can add a strong link in Y:
XY ..... XY = Y or Y = XY ..... XY
and the end cells are pincers on Y.
The half Mwing does not need a complementary pair. All it needs is the following:
XY ..... aXY
where X in the first cell forces X in the cell containing aXY where a is any other candidates. Then you can add the strong link on Y:
XY ..... aXY = Y
and the end cells are pincers on Y.
It's a "half" wing because it only works one way. There is no requirement that X in aXY has any implication for the cell XY.
Over time, we've forgotten the distinction.
Keith 
The "half" mwing is a sis 3 like all other wings. The original must have been a sis 5?
Thanks Keith 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5499 Location: Rochester, NY, USA


Back to top 




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
