two "new" techniques, Skyscraper and 2-string Kite

Advanced methods and approaches for solving Sudoku puzzles

Postby Havard » Tue Jan 24, 2006 12:58 pm

I suppose the only problem I have with it is that you call them "new" techniques when they are just specific examples (not even really techniques) derived from an existing and fairly well known technique. If you want to propose giving particular turbot fish patterns names, you should probably make your title reflect that.


I see your point, but when I discovered them they were new to me, and I was really excited about them because they helped solve a lot of the sudokus on menneske.no that was said to require Nishio. Then (luckily) I did some research on this forum, and found that the "Turbot Fish" pattern already covered these, so, alas, I was not the first one to spot them.

However I did think (and still do) that these patterns are quite useful. First of all because Turbot Fish with all it's patterns can be reduced to only three different ones. (see my post above), and I have named two of the three, hence the patterns are a lot more general than "just specific examples" of the Turbot Fish.

Or said in another way, there is nothing Turbot Fish can do, that can't be done with a Skyscraper, 2-string Kite and the "fish" pattern.:)

Havard
Havard
 
Posts: 377
Joined: 25 December 2005

oh man!!!u crcked it all

Postby hytechpro » Wed Jan 25, 2006 7:02 am

hey ......
whts up !!wel u r master blaster yaar !!i really wonder u shaked this all ...cool ...but tell ur techniques in detail to me so tht even i can work on them better .....plz plz ...i m a gr8 fan of this real mind puzzle
help help help
devs
hytechpro
 
Posts: 3
Joined: 26 September 2005

Postby Marzy » Sat Feb 04, 2006 6:18 am

What I dont get is why do we have to have these names for? Its very confusing when you are trying to look out for these patterns and cant find them. Wouldnt it be easier if you looked at each puzzle indiviually and completed the puzzle with the 'clues' provided instead of trying to place each pattern into the puzzle?
Marzy
 
Posts: 3
Joined: 21 December 2005

Postby Havard » Sat Feb 04, 2006 11:46 am

Hi Marzy.

Try this puzzle:
Code: Select all
. . . | 8 . . | . 2 .
. . 9 | 3 . . | . 8 4
. . 8 | 2 . . | 6 . 7
------+-------+------
. . 4 | 7 . . | 8 . .
. 6 . | . . . | . 5 .
. . 1 | . . 5 | 4 . .
------+-------+------
4 . 5 | . . 7 | 9 . .
8 1 . | . . 2 | 3 . .
. 7 . | . . 8 | . . .


If you get stuck you get get my program at www.sudoku.frihost.net and it will tell you where the skyscraper lurks!:)

havard
Havard
 
Posts: 377
Joined: 25 December 2005

Postby JeffInCA » Sat Feb 04, 2006 8:01 pm

I'm just going to throw my 2 cents in here, since I'm relatively new to the forum.

Essentialy, I have to agree with vidriano's post

IMHO, adding new names for easily recognized patterns doesn't have to be such a terrible idea. We still call it XY-wing, even though it's just a short Forcing Chain, right? And X-Wing and Turbot Fish are just X-Cycles. Heck, even X-Cycles is a special case of Grouped X-Cycles, where all the groups are of size 1. ;)


I would consider myself fairly competent at solving sudoku puzzles, and I'm getting better by following this forum. That being said, I certainly haven't been doing this as long as Jeff, Carcul, Myth Jellies, tso, and all the rest of you veterans out there who are defining some of the most advanced solving patterns.

I have to believe that there are many more people out there at my level, new to advanced sudoku and just trying to improve their understanding. In that vain, having these named "examples" of more general techniques is an invaluable stepping stone.

Also, having to break down and perform a detailed bilocation / bivalue plot to solve a puzzle can be a very time consuming proposition from what I can see from many of the diagrams posted here.

In that vain, I think it's great to have some names for specific instances of these general rules/patterns to help "visualize" them by simply looking at the cells and their candidates.

While it's true that for theoretical discussions, having too many names for the same thing can be problematic, this is the only time that is a problem. So use the "official" names when having theoretical discussions, but use the "user-friendly" names like the ones Harvard is coming up with when actually trying to solve a puzzle in your mind.

Happy solving,

Jeff
JeffInCA
 
Posts: 33
Joined: 02 January 2006

Skyscraper

Postby ehutchi » Sat Feb 04, 2006 11:17 pm

Hi Havard in reference to your skyscraper, I am confused that you say B and D are in the same box area? In your example they are in 2 different boxes.... Thanks
ehutchi
 
Posts: 2
Joined: 04 February 2006

Postby Havard » Sun Feb 05, 2006 1:36 am

Hi ehutchi!

I'll try to explain!:)

the two "tops" of the skyscraper have to be within the same box-area, and by "box-area" I mean:

Code: Select all
example "box-area":
* * * | * * * | * * *
* * * | * * * | * * *
* * * | * * * | * * *
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .

another example:
* * * | . . . | . . .
* * * | . . . | . . .
* * * | . . . | . . .
------+-------+------
* * * | . . . | . . .
* * * | . . . | . . .
* * * | . . . | . . .
------+-------+------
* * * | . . . | . . .
* * * | . . . | . . .
* * * | . . . | . . .



not quite sure how to explain it properly, but hope the illustrations make it clear...?:)

valid skyscrapers:

Code: Select all
. . . | . . . | . . .
. . . | . d . | . . .
. . b | . | . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . | | . | . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . a | . c . | . . .

. . . | . d . | . . .
. . . | . | . | . . .
. . b | . | . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . | | . | . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . a | . c . | . . .

. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
---------------------
. . b | . . . | . . .
. . | | . . . | . . .
. . | | . d . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . a | . c . | . . .


invaild skyscrapers:

Code: Select all
. . . | . . . | . . .
. . . | . d . | . . .
. . . | . | . | . . .
----------|----------
. . b | . | . | . . .
. . | | . | . | . . .
. . | | . | . | . . .
----|-----|----------
. . | | . | . | . . .
. . | | . | . | . . .
. . a | . c . | . . .

. . . | . . . | . . .
. . . | . . . | . . .
. . b | . . . | . . .
----|----------------
. . | | . . . | . . .
. . | | . . . | . . .
. . | | . . . | . . .
----|----------------
. . | | . d . | . . .
. . | | . | . | . . .
. . a | . c . | . . .


so you can think of it like the skyscrapers have to be of "similar height", or in the same "height class" if you want!:)

you get it?

havard
Havard
 
Posts: 377
Joined: 25 December 2005

Postby ehutchi » Sun Feb 05, 2006 5:29 am

Thanks Havard...now I understand!
ehutchi
 
Posts: 2
Joined: 04 February 2006

Postby Havard » Fri Feb 10, 2006 10:55 am

hi again!

In my every ongoing struggle to identify "easy-to-spot-easy-to-remember-patterns" so that one day Nishio would be useless, I present this little pattern today!:D

Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . a | . . . | . . .
* * | | . e . | . . .
. . b | . | . | . . .
----|-+---|---+------
. . | | . | . | . . .
. . c | . d . | . . .
. . . | . . . | . . .


if a-b-c is the only three candidates in a line (here column) (does this have a name? I'll call it semi-strong-link...:) ), and d-e is a strong link, and a and b are in the same box and c and d are on the same line, and e is somewhere in the same "box-area" you can eliminate occurences of that candidate in the a-b box on the e line. (phew, the examples make it look a lot easier than that... )

this also works for:
Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . a | . . . | . . .
. . | | . . . | . . .
* * b | . . e | . . .
----|-+-----|-+------
. . | | . . | | . . .
. . | | . . | | . . .
. . c | . . d | . . .

and:
Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
* * a | . . . | . . e
. . | | . . . | . . |
. . b | . . . | . . |
----|-+-------+-----|
. . c | . . . | . . d
. . . | . . . | . . .
. . . | . . . | . . .


I'll call this the "extended skyscraper" because it pretty much follows the defintion of a skyscraper, and if you were looking for skyscrapers, this one would easily present itself. (looks like one too):D

havard
Havard
 
Posts: 377
Joined: 25 December 2005

Postby Carcul » Fri Feb 10, 2006 11:01 am

Hi Havard.

Havard wrote:if a-b-c is the only three candidates in a line (here column) (does this have a name? I'll call it semi-strong-link...


Your three candidates are distributed by only two units, and so its a grouped strong link. The deductions that you have shown are simply grouped Turbot Fishes, already known. Please note that if your three candidates where distributed by three units, then you could not simply make deductions (unless if one uses a trilocation triangle, which is quite hard).

Regards, Carcul
Carcul
 
Posts: 724
Joined: 04 November 2005

Postby tarek » Fri Feb 10, 2006 11:10 am

Havard wrote:
Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . a | . . . | . . .
* * | | . e . | . . .
. . b | . | . | . . .
----|-+---|---+------
. . | | . | . | . . .
. . c | . d . | . . .
. . . | . . . | . . .


Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
. . a | . . . | . . .
. . | | . . . | . . .
* * b | . . e | . . .
----|-+-----|-+------
. . | | . . | | . . .
. . | | . . | | . . .
. . c | . . d | . . .

and:
Code: Select all
. . . | . . . | . . .
. . . | . . . | . . .
. . . | . . . | . . .
------+-------+------
* * a | . . . | . . e
. . | | . . . | . . |
. . b | . . . | . . |
----|-+-------+-----|
. . c | . . . | . . d
. . . | . . . | . . .
. . . | . . . | . . .


hi Havard,

Have you read the Filet-O-Fish thread started by MythJellies, the examples above are actually CLASSIC examples of an almost finned x-wing (Sashimi, #1) & finned x-wings (#2 & #3), Your skyscraper has been already described in a way which makes it easy to identify & it was extensively discussed with the its applications reaching far beyond the 4 vertices grouping.

Tarek
Last edited by tarek on Fri Feb 10, 2006 7:17 am, edited 1 time in total.
User avatar
tarek
 
Posts: 2622
Joined: 05 January 2006

Postby Marzy » Fri Feb 10, 2006 11:12 am

Thanks Havard I will try that website and maybe things will be clearer
Marzy
Marzy
 
Posts: 3
Joined: 21 December 2005

Postby Havard » Fri Feb 10, 2006 11:16 am

hi carcul

Carcul wrote:Hi Havard.
Your three candidates are distributed by only two units, and so its a grouped strong link. The deductions that you have shown are simply grouped Turbot Fishes, already known.

"grouped strong link"... noted!:)
I have no doubt that they are already known. Maybe you can show me some other patterns that fall in under grouped Turbot Fishes?

Carcul wrote:Hi Havard.
Please note that if your three candidates where distributed by three units, then you could not simply make deductions (unless if one uses a trilocation triangle, which is quite hard).


already noted, I made a remark about that in my post:
...and a and b are in the same box...
Havard
 
Posts: 377
Joined: 25 December 2005

Postby Havard » Fri Feb 10, 2006 11:21 am

tarek wrote:hi Havard,

Have you read the Filet-O-Fish thread started by MythJellies, the examples above are actually CLASSIC examples of an almost finned x-wing (Sashimi, #1) & finned x-wings (#2 & #3Tarek


No, I must check it out!:)
Havard
 
Posts: 377
Joined: 25 December 2005

Postby Havard » Fri Feb 10, 2006 11:26 am

tarek wrote:Your skyscraper has been already described in a way which makes it easy to identify & it was extensively discussed with the its applications reaching far beyond the 4 vertices grouping.


I don't quite understand what you mean? Can you explain?

havard
Havard
 
Posts: 377
Joined: 25 December 2005

PreviousNext

Return to Advanced solving techniques