| View previous topic :: View next topic |
| Author |
Message |
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
 Posted: Mon Jul 19, 2010 12:38 am Post subject: A rare DP |
 |
|
I have not before seen this Deadly Pattern in a real puzzle.
Beyond that, I was not able to get to a solution I am happy with.
| Code: | Puzzle: M3916198sh(16)
+-------+-------+-------+
| . . 7 | 5 . 8 | . . 6 |
| . 2 . | 3 . 6 | 8 . . |
| 8 . . | . . . | . . . |
+-------+-------+-------+
| 4 1 . | . . . | . 6 9 |
| . . . | . . . | . . . |
| 9 7 . | . . . | . 3 5 |
+-------+-------+-------+
| . . . | . . . | . . 3 |
| . . 4 | 7 . 5 | . 2 . |
| 2 . . | 4 . 3 | 1 . . |
+-------+-------+-------+ |
Keith |
|
| Back to top |
|
 |
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Mon Jul 19, 2010 1:04 am Post subject: |
|
|
| It solved for me with an XY-Wing (596). Let me know if you think I need to do it again. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Mon Jul 19, 2010 1:25 am Post subject: |
|
|
| Marty R. wrote: | | It solved for me with an XY-Wing (596). Let me know if you think I need to do it again. |
After basics: | Code: | +----------------+----------------+----------------+
| 13 4 7 | 5 2 8 | 39 19 6 |
| 15 2 159 | 3 79 6 | 8 157 4 |
| 8 3569 3569 | 1 479 49 | 35 57 2 |
+----------------+----------------+----------------+
| 4 1 35 | 8 35 27 | 27 6 9 |
| 356 356 2 | 9 35 47 | 47 8 1 |
| 9 7 8 | 26 146 124 | 24 3 5 |
+----------------+----------------+----------------+
| 7 5689 1569 | 26 1689 129 | 569 4 3 |
| 136 369 4 | 7 169 5 | 69 2 8 |
| 2 5689 569 | 4 689 3 | 1 59 7 |
+----------------+----------------+----------------+ |
I see a DP that is not much help. I do not see any wings.
Keith |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Mon Jul 19, 2010 3:42 am Post subject: |
|
|
| I had a couple of fewer candidates, erroneously or otherwise. |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Mon Jul 19, 2010 5:07 am Post subject: |
|
|
I'll concede defeat .  |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Mon Jul 19, 2010 5:28 pm Post subject: |
|
|
This is the most reasonable solution I could find using my solver.
UR, 2x XY-Chain, XY-Wing, 2x in-one XY-Chain:
| Code: | +--------------------------------------------------------------+
| 13 4 7 | 5 2 8 | 39 19 6 |
| 15 2 159 | 3 79 6 | 8 157 4 |
| 8 3569 3569 | 1 479 49 | 35 57 2 |
|--------------------+--------------------+--------------------|
| 4 1 35 | 8 35 27 | 27 6 9 |
| 356 356 2 | 9 35 47 | 47 8 1 |
| 9 7 8 | 26 146 124 | 24 3 5 |
|--------------------+--------------------+--------------------|
| 7 5689 1569 | 26 1689 129 | 569 4 3 |
| 136 369 4 | 7 169 5 | 69 2 8 |
| 2 5689 569 | 4 689 3 | 1 59 7 |
+--------------------------------------------------------------+
# 66 eliminations remain
r58c12 <36> UR via s-link <> 3 r5c1
(6=5)r5c1 - (5=1)r2c1 - (1=3)r1c1 - (3=9)r1c7 - (9=6)r8c7 => r8c1<>6
(9=1)r2c3 - (1=7)r2c8 - (7=5)r3c8 - (5=9)r9c8 => r9c3<>9
<59+6> XY-Wing r9c8/r8c7+r9c3 <> 6 r8c2
********************************************* => r8c7<>9
(9=7)r2c5 - (7=1)r2c8 - (1=9)r1c8 - (9=3)r1c7 - (3=1)r1c1 - (1=3)r8c1 - (3=9)r8c2 => r8c5<>9
______________________________________________________________________________________________
|
|
|
| Back to top |
|
|
tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
|
| Posted: Mon Jul 19, 2010 8:27 pm Post subject: Re: A rare DP |
|
|
| keith wrote: | I have not before seen this Deadly Pattern in a real puzzle.
Beyond that, I was not able to get to a solution I am happy with.
| Code: | Puzzle: M3916198sh(16)
+-------+-------+-------+
| . . 7 | 5 . 8 | . . 6 |
| . 2 . | 3 . 6 | 8 . . |
| 8 . . | . . . | . . . |
+-------+-------+-------+
| 4 1 . | . . . | . 6 9 |
| . . . | . . . | . . . |
| 9 7 . | . . . | . 3 5 |
+-------+-------+-------+
| . . . | . . . | . . 3 |
| . . 4 | 7 . 5 | . 2 . |
| 2 . . | 4 . 3 | 1 . . |
+-------+-------+-------+ |
Keith |
Keith,
I recall finding a Type 1 MUG some time ago but I do not have a reference to it.
Ted |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Mon Jul 19, 2010 10:00 pm Post subject: |
|
|
Ted,
I don't know what a Type 1 MUG is. I was a little surprised that no one asked which DP I was talking about.
What I meant was this:
| Code: | +-------------------+--------------------+
| . . 27 | 27 . . |
| . . 47 | 47 . . |
| . . 124 | 24 . . |
+-------------------+--------------------+
|
The cell 124 must be 1. I cannot recall ever seeing this before.
What I have seen is the following, I recall it being pointed out by Marty:
| Code: |
+--------------------+
| 27 27 . |
| . . . |
| . . . |
+--------------------+
| . . . |
| 47 47 . |
| . . . |
+--------------------+
| . . . |
| . . . |
| 124 24 . |
+--------------------|
|
Again, the cell 124 must be 1.
For me, these are basically the same. But, if you are one to enumerate case, types and variants, they are different.
Also, I would imagine, the solver code to pick up either of the above is quite different.
Keith
(By the way, I am not at all suggesting no one has defined such a possible pattern. All I am saying is, I have not before seen it in the wild.) |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Mon Jul 19, 2010 10:08 pm Post subject: |
|
|
And, I checked:
There is no entry for MUG in Sudopedia.
Also, Danny's solution above does not include R6C6 <>1. (To be fair, he was looking for the simplest path, not a DP elimination.) |
|
| Back to top |
|
|
ronk
Joined: 07 May 2006
Posts: 398
|
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Tue Jul 20, 2010 12:08 am Post subject: |
|
|
| keith wrote: | | Also, Danny's solution above does not include R6C6 <>1. (To be fair, he was looking for the simplest path, not a DP elimination.) |
I don't know how to find DPs beyond the UR variety, so I (and my solver) completely missed your BUG-Lite. Congratulations on catching it!
Regards, Danny |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Tue Jul 20, 2010 1:57 am Post subject: |
|
|
"Bible"? Seems more like the Dead Sea Scrolls. The article you refer to is also not cited in the archaeology version of Mike Barker's solving methods:
http://Forum.EnjoySuDoku.com/viewtopic.php?t=3315
I don't know what a solution is, but so much good stuff has been lost, or simply forgotten!
Keith |
|
| Back to top |
|
|
ronk
Joined: 07 May 2006
Posts: 398
|
| Posted: Tue Jul 20, 2010 2:27 am Post subject: |
|
|
Feel free to post a link to a more authoritative thread on the topic. |
|
| Back to top |
|
|
Luke451
Joined: 20 Apr 2008
Posts: 310
Location: Southern Northern California
|
| Posted: Tue Jul 20, 2010 6:02 am Post subject: |
|
|
| ronk wrote: | | Feel free to post a link to a more authoritative thread on the topic. |
Not MUG orientated, but the Deadly Pattern Sudopedia entry has a useful collection of BUG-Lite archetypes.
Keith, your nice Bug-Lite is the third entry under "6 cells" (six celled BUG-Lite patterns):
| Code: | 12 . . | 21 . . | . . .
23 . . | 32 . . | . . .
31 . . | 13 . . | . . . |
I always think of any deadly pattern with only one extra candidate as a Type 1, why not... |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Tue Jul 20, 2010 8:01 am Post subject: |
|
|
| ronk wrote: | | Feel free to post a link to a more authoritative thread on the topic. |
ronk,
a) I Googled "Sudoku MUG" and found many coffee mugs for sale.
b) I looked in Sudopedia and did not find MUG
c) I looked at Mike Barker's list of solving techniques, and did not find the thread you cite.
The best thing I can think of is that someone should add the definition of MUG and appropriate links to MUG threads in Sudopedia. Even better would be an article on MUG in Sudopedia.
So far as Sudopedia goes, I think it is the best thing we have. Sure, there are parts I disagree with (in terms of exposition) and there is an entry (or two) that infuriates me, but some people have put much time and effort into it.
I don't have any authoritative threads. I can't even find the ones that are out there!
Keith |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Tue Jul 20, 2010 3:11 pm Post subject: |
|
|
Apparently, one of Mike Barker's last actions in the Players' Forums was to update his solving techniques post in October of 2008. However he seems to have missed including Myth Jellies entry for MUG in May of that year. Obviously, any solving technique that came along since Mike Barker updated his post is also going to be missing. It would be nice if someone had taken over updating that thread. Maybe ronk can start by adding a message where MJ's latest MUG thread has a link.
Sudopedia is a great effort by Ruud and many others to create a great reference site for Sudoku. However, just because something hasn't been added doesn't mean that it doesn't exist. It just means that the chances of finding a good definition and/or examples may be few and far between.
Regards, Danny |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Wed Jul 21, 2010 12:40 am Post subject: |
|
|
Okay, it's soap box time!!!
| Sudopdia wrote: | A deadly pattern is a set of cells whose candidates form a pattern that causes the puzzle to have multiple solutions.
|
This is the definition that (almost) everyone uses -- except me.
So, let's take the grid and perform r6c6<>1 ... this should force the deadly pattern to create multiple solutions.
| Code: | +--------------------------------------------------------------+
| 13 4 7 | 5 2 8 | 39 19 6 |
| 15 2 159 | 3 79 6 | 8 157 4 |
| 8 3569 3569 | 1 479 49 | 35 57 2 |
|--------------------+--------------------+--------------------|
| 4 1 35 | 8 35 27 | 27 6 9 |
| 356 356 2 | 9 35 47 | 47 8 1 |
| 9 7 8 | 26 146 24-1 | 24 3 5 |
|--------------------+--------------------+--------------------|
| 7 5689 1569 | 26 1689 129 | 569 4 3 |
| 136 369 4 | 7 169 5 | 69 2 8 |
| 2 5689 569 | 4 689 3 | 1 59 7 |
+--------------------------------------------------------------+
# 66 eliminations remain
|
After forcing one choice for the DP, I end up with:
| Code: | *--------------------------------*
| 3 4 7 | 5 2 8 | 9 1 6 |
| 5 2 9 | 3 7 6 | 8 4 |
| 8 6 5 | 1 4 9 | 3 7 2 |
|----------+----------+----------|
| 4 1 3 | 8 5 2 | 7 6 9 |
| 6 5 2 | 9 3 7 | 4 8 1 |
| 9 7 8 | 6 1 4 | 2 3 5 |
|----------+----------+----------|
| 7 9 6 | 2 8 1 | 5 4 3 |
| 1 3 4 | 7 9 5 | 6 2 8 |
| 2 8 | 4 6 3 | 1 9 7 |
*--------------------------------*
|
After forcing the other choice for the DP, I end up with:
| Code: | *--------------------------------*
| 3 4 7 | 5 2 8 | 9 1 6 |
| 5 2 9 | 3 7 6 | 8 4 |
| 8 6 5 | 1 4 9 | 3 7 2 |
|----------+----------+----------|
| 4 1 3 | 8 5 7 | 2 6 9 |
| 6 5 2 | 9 3 4 | 7 8 1 |
| 9 7 8 | 6 1 2 | 4 3 5 |
|----------+----------+----------|
| 7 9 6 | 2 8 1 | 5 4 3 |
| 1 3 4 | 7 9 5 | 6 2 8 |
| 2 8 | 4 6 3 | 1 9 7 |
*--------------------------------*
|
Where are the multiple solutions?
I always end up with grids that have one or more empty cells; i.e., zero solutions!!! |
|
| Back to top |
|
|
ronk
Joined: 07 May 2006
Posts: 398
|
| Posted: Wed Jul 21, 2010 1:48 am Post subject: |
|
|
| daj95376 wrote: | Where are the multiple solutions?
I always end up with grids that have one or more empty cells; i.e., zero solutions!!! |
That's because we're working with puzzles that have unique solutions, and you're deleting a candidate that would ultimately be true. |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Wed Jul 21, 2010 3:08 am Post subject: |
|
|
| ronk wrote: | | daj95376 wrote: | Where are the multiple solutions?
I always end up with grids that have one or more empty cells; i.e., zero solutions!!! |
That's because you're working with puzzles that have unique solutions. |
So, a puzzle must already have multiple solutions before a deadly pattern in the candidate grid will produce multiple solutions. This reminds me of a dog chasing his tail. _  _
Seriously, I understand the role of a deadly pattern of single digit values in a solution grid where one of the values must be present as a clue/given in any uniquely solveable puzzle associated with that solution grid.
[Edit: dropped this paragraph because it wasn't right.]
Okay, I'm off the soap box!!!
Last edited by daj95376 on Wed Jul 21, 2010 5:38 am; edited 1 time in total |
|
| Back to top |
|
|
daj95376
Joined: 23 Aug 2008
Posts: 3854
|
| Posted: Wed Jul 21, 2010 5:52 am Post subject: |
|
|
| keith wrote: | As I understand it, a DP can result in more than one, or no, solutions.
Certainly, it seems that a UR is predicated on avoiding multiple solutions.
|
I go by the following:
If a puzzle has multiple solutions, then a DP would contribute to those solutions.
If a puzzle has a unique solution, then a DP can not exist and, if one is used, then it will lead to zero solutions.
| keith wrote: | But, it seems to me, a BUG+1 seeks a valid solution among those that are invalid.
|
I always thought that a BUG+1 consisted of one candidate preventing the remaining candidates from forming one huge DP.
Regards, Danny |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
