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Collection of solving techniques

Advanced methods and approaches for solving Sudoku puzzles
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Collection of solving techniques

Postby chopsuey » Sun Feb 26, 2006 10:51 pm

Hi,
Im quiet new to this forum and would be glad, if all the wisdom of the people wrote here over the years is easily accessible to other new members, by having a sticky post on the first page with all the links to the most important threads, where the different techniques are explained, because I noted, that in the last weeks for example, quiet a few guys ask for a explaination of the coloring technique.
Futhermore this helps the newbies to get used to the most common technical terms here.

I start with the following ones:

POM Analysis of the X-Wing: The Filet-O-Fish Rule
http://forum.enjoysudoku.com/viewtopic.php?t=2793

Almost locked rules (for now)
http://forum.enjoysudoku.com/viewtopic.php?t=2510

Two-Sector Disjoint Subsets: Sue De Coq
http://forum.enjoysudoku.com/viewtopic.php?t=2033

The Empty Rectangle (ER)
http://forum.enjoysudoku.com/viewtopic.php?t=3251

Greetings
Chopsuey
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Re: Collection of solving techniques

Postby angusj » Sun Feb 26, 2006 11:43 pm

chopsuey wrote:Futhermore this helps the newbies to get used to the most common technical terms here.

I start with the following ones

LOL. I really don't think the techniques in your list will help 'newbies' at all. On the contrary, it's most likely to discourage them. The techniques you've mentioned are at the most extreme/obscure end of the solving spectrum. (They may be discussed a lot here by a very few who are keen to continue pushing solving techniques to the absolute limits.)

What you've proposed is akin to offering a Formula One car to a learner driver.

Edit: I apologise for criticising your list. I now realise you were simply trying to start a list and were looking for contributions.
Last edited by angusj on Mon Feb 27, 2006 7:14 pm, edited 1 time in total.
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Postby chopsuey » Mon Feb 27, 2006 12:50 am

Of course I can speak only for myself, but this is the forum for advanced solving techniques, and although these threads are discussed by only a few, the basic ideas are clearly formulated there and are understandable by all people, who gets involved with Sudokus, thats why I choose them.
And I want to point out, that I meant forum newbies, not Sudoku newbies.
So I want to encourage you all to help to create an overview over the techniques posted here.
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Postby Mike Barker » Mon Feb 27, 2006 1:28 am

Some good general sources for solving techniques for Sudoku puzzles include:
-----http://www.sudocue.net/guide.php
-----http://www.paulspages.co.uk/sudokuxp/howtosolve
-----http://www.sadmansoftware.com/sudoku/techniques.htm
-----http://www.angusj.com/sudoku/hints.php
-----http://www.scanraid.com/BasicStrategies.htm
-----http://www.stolaf.edu/people/hansonr/sudoku/explain.htm
-----http://homepages.cwi.nl/~aeb/games/sudoku/

The Sudopedia of Sudoku terminology is found athttp://www.sudopedia.org/wiki/Terminology coupled with an extensive summary of solving techniques found athttp://www.sudopedia.org/wiki/Solving_technique

A dictionary of terms used at this site can be found athttp://www.playr.co.uk/sudoku/dictionary.php andhttp://www.sudocue.net/glossary.php
A short list of terms that should be used at this site is found athttp://forum.enjoysudoku.com/viewtopic.php?t=4120
A description of the notation used for Nice Loops and Single Implication Networks is found athttp://forum.enjoysudoku.com/viewtopic.php?t=3628
Use of the BBCode editor is described athttp://forum.enjoysudoku.com/faq.php?mode=bbcode
To link directly to this post usehttp://forum.enjoysudoku.com/viewtopic.php?p=21804#p21804

Some good Sudoku puzzle solvers include:
----- Angus Johnson's Simple Sudoku athttp://www.angusj.com/sudoku/
----- Robert Woodhead's Sudoku Susser athttp://www.madoverlord.com/projects/sudoku.t
----- Guenter Stertenbrink's (dukuso) Suexk athttp://magictour.free.fr/sudoku.htm andhttp://magictour.free.fr/suexratt.exe
----- Ruud's Sudocue athttp://www.sudocue.net/download.php
----- Nicolas Juillerat's Sudoku Explainer athttp://diuf.unifr.ch/people/juillera/Sudoku/Sudoku.html
----- Glenn Fowler's (gsf) Solver athttp://www.research.att.com/~gsf/sudoku/
----- Havard Graff's Sudoku Assistenten athttp://www.sudoku.frihost.net/
----- Andrew Stuart's on-line solver athttp://www.scanraid.com/sudoku.htm
----- Bob Hanson's on-line Sudoku Assistant athttp://www.stolaf.edu/people/hansonr/sudoku/

Several of the many good sites to find Sudoku puzzles include:
-----http://www.sudoku.com.au/
-----http://www.sudoku.org.uk
-----http://www.websudoku.com
-----http://www.sudocue.net/daily.php

Here's my list of Sudoku solving techniques based in part on the listings at theSudoku Programmers Forum. Examples for many of these techniques can be found atthe Benchmark Sudoku List,the Effortless Extreme Thread,Some Interesting Sudokus,Sudoku Explainer Rated Puzzles, andthe Zoo.
Finally some common acronyms (see alsohttp://alinconstantin.homeip.net/WebDocs/BBS_Acronyms.htm):
    AFAIK As far as I know
    BTW By the way
    IMO In my opinion
    IMHO In my humble opinion
    IOW In other words
    LOL Laughing out loud
    POV Point of View
Last edited by Mike Barker on Fri Oct 03, 2008 9:38 am, edited 134 times in total.
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Postby chopsuey » Mon Feb 27, 2006 5:28 pm

Thx Mike, your help is much appreciated.
Thats, what I had in mind...
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Postby tso » Mon Mar 06, 2006 4:43 pm

Thank you *very* much for making this post Mike. It'll be the most pointed to page in the forum.
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Postby angusj » Mon Mar 06, 2006 10:31 pm

Here's my list:

Code: Select all
 

The Basics (Sudoku without candidates)
    http://palmsudoku.com/pages/techniques-overview.php
    http://www.puzzle.jp/keys/sudoku_mid02-e.html
    http://www.conceptispuzzles.com/products/sudoku/solution_examples.htm

Beyond the basics (candidates)
* locked candidates,
* naked pairs, naked triples, naked quads,
* hidden pairs, hidden triples, hidden quads
    http://angusj.com/sudoku/hints.php

Advanced
* X-Wing, Swordfish (& Jellyfish)
    http://www.sudoku.com/boards/viewtopic.php?p=13113#p13113
* Simple Colours
      http://www.setbb.com/phpbb/viewtopic.php?p=1562&mforum=sudoku#1562
      http://www.setbb.com/phpbb/viewtopic.php?p=3878&mforum=sudoku#3878
     ....75....1..2.....4...3...5.....3.2...8...1.......6.....1..48.2........7........ (6's in row 7)
     ...6.3...74.....1......59.....34...119....7.42...5......1...2...2..6..7....5...6. (3's)
     1.3.....9..6.......8....54.....49..36......2....1...5...89..2.4..73....1.4....... (6's)
     6..9.....5..1....71.38....4..6...93.....2.........5.82..1......2.....4138...3.... (4's)
     .6..3....1..2.....2...7..5.9........5..8...41.....29.8.......64.....6.....41.95.2 (3's)
     63......4..5......74..3..6..2.4.5........19......6...7..4.2..9.25.9.8......5..1.. (1's partially solves only)
     8...7......4..53...7.2...4...9....2..........5.3.8.1...6...4.7.......5.6....67..3 (6's)
      http://www.sudoku.com/boards/viewtopic.php?p=19119#p19119

* Turbot fish (http://sudoku.com/boards/viewtopic.php?t=833)
* Modified Swordfish: http://www.sudoku.com/boards/viewtopic.php?p=14493#p14493
* 2 jellyfish:
      ...6..1..83.......5........2.....43....1..2.....75.....71..........8..5.....3....
      69...2..........31...........314....2.....6.....3........71..4.86....5...........

Expert
* XY-Wing
      http://www.sudoku.com/boards/viewtopic.php?p=17589#p17589
      http://sudoku.com/boards/viewtopic.php?t=992
* Multi-colours
      http://www.setbb.com/phpbb/viewtopic.php?p=2575&mforum=sudoku#2575
      http://www.setbb.com/phpbb/viewtopic.php?p=1412&mforum=sudoku#1412
      see also http://www.sudoku.com/boards/viewtopic.php?p=12457#p12457
* Sue De Coq: http://www.sudoku.com/boards/viewtopic.php?p=12549#p12549

Extreme
* Extended multi-colors:
      http://www.setbb.com/phpbb/viewtopic.php?p=3456&mforum=sudoku#3456
* XYZ-Wing (http://www.sudoku.com/boards/viewtopic.php?t=1103)
* (Bi-value) xy-chains (http://www.sudoku.com/boards/viewtopic.php?p=6625)
* (Bi-location) Forcing Chains (http://www.sudoku.com/boards/viewtopic.php?p=9266#p9266)
* More on chains -
      http://www.sudoku.com/boards/viewtopic.php?p=10636#p10636
      http://www.setbb.com/phpbb/viewtopic.php?p=2148&mforum=sudoku#2148
    "In a simple forcing chain, each step implies the next, by itself. If a step needs more than one previous step to be inferred, then you have a forcing NET. In my opinion a NET is generally more difficult to follow in one's head, more difficult to find, more difficult to write down."

Esoteric
  technique related to forcing chains:
      http://www.sudoku.com/boards/viewtopic.php?p=14679#p14679
* Remote pairs (see http://www.scanraid.com/RemotePairs.htm)
* xyz-chain (http://www.sudoku.com/boards/viewtopic.php?p=8966#p8966)
* sets:
      http://www.sudoku.com/boards/viewtopic.php?t=2510
      http://www.sudoku.com/boards/viewtopic.php?p=17439#p17439
* Trial and Error
    'Bifurcation', Nishio, backtracking == "proof by contradiction"
    Nishio
      Trial and Error that you can do in your head (ie without having to resort to erasing pencilmarks or solver undos).
      http://www.setbb.com/phpbb/viewtopic.php?t=11&mforum=sudoku
* Uniqueness
      http://www.sudoku.com/boards/viewtopic.php?p=12130#p12130
* BUG (http://www.sudoku.com/boards/viewtopic.php?p=14899#p14899)

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Postby swaditi » Wed Mar 08, 2006 10:08 am

hello and thanks so much.
i had visited some of the sites, but had a hard time understanding some of the steps.
i consider myself ready to move to the "wicked" puzzles and now feel empowered!!!!
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Postby ronk » Wed Mar 08, 2006 1:02 pm

Mike Barker wrote:Some good general sources for Sudoku puzzles are:

----- Multi Colouring http://www.setbb.com/phpbb/viewtopic.php?p=2575

Mike, that's an excellent library of links. Thanks for sharing.

I notice a number of links that end in "p=nnnn" like the "p=2575" above. Based on that "p=nnnn", it appears your intent was to link directly to a certain post within a topic ... *not* to the start of the topic. If so, I believe that only works if the link ends in "p=nnnn#nnnn" such as ...

http://www.setbb.com/phpbb/viewtopic.php?p=2575#p2575

... and you might consider editing your post.

TIA, Ron
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Postby Mike Barker » Wed Mar 08, 2006 1:46 pm

I believe the p= without a # is the same as a t=. Some of the links especially the one you noted seem to be intermittent. Changing the p to a t didn't seem to help and in some cases made things "look" worse - Links I had gotten to with a p failed with a t. Probably just random luck. I made some changes, but in general it seemed to be better to leave well enough alone.
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Postby ronk » Wed Mar 08, 2006 2:02 pm

Mike Barker wrote:Changing the p to a t didn't seem to help and in some cases made things "look" worse - Links I had gotten to with a p failed with a t. Probably just random luck.

If you change p to t, you have to change the number too. The post number is very unlikely to be the same as the topic number.

Did you try both links in my post? (the first being a quote of your link)

Ron
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Postby Mike Barker » Wed Mar 08, 2006 2:19 pm

In general, I was trying to go to the top of the topic, because often the context helps alot. A p= or t= gets me there (obviously the p= came about because I deleted the specific post reference). In this case (and probably a few others going to the specific post makes more sense. I'll edit the reference and others as they come up. Otherwise I'm off on vacation for the rest of the week.
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Please add a post to this topic if you want a change

Postby Mike Barker » Sun Mar 12, 2006 2:54 am

I don't have a chance to read all of the posts and in several I have I've found requests to change the collection of solving techniques:( . Please add a post to this topic if you would like to see something added or modified and I'll try to take care of it:) . Thanks.
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Re: Please add a post to this topic if you want a change

Postby Jeff » Sun Mar 12, 2006 7:06 am

Mike, Could you list the following threads under the heading of Nice Loop please. I realise that some of these threads are already listed under other headings. But could they be also listed under nice loop where they are related. Thanks.

Almost Unique Rectangles: description and application in advanced nice loops
http://forum.enjoysudoku.com/viewtopic.php?t=2751&sid=f589e5965773a4984919b3de9a963fdb

Nice loops for elementary level players - the x-cycle
http://forum.enjoysudoku.com/viewtopic.php?t=2752

Nice loops for intermediate level players - Grouped x-cycle
http://forum.enjoysudoku.com/viewtopic.php?t=2764

Nice loops for advanced level players - multiple nice loop
http://forum.enjoysudoku.com/viewtopic.php?t=2412

Nice loops for elementary level players - the xy-chain
http://forum.enjoysudoku.com/viewtopic.php?t=2966

Nice loops for intermediate level players - Grouped xy-chain
http://forum.enjoysudoku.com/viewtopic.php?p=19364#p19364

Almost x-wing nice loop
http://forum.enjoysudoku.com/viewtopic.php?p=17761#p17761

Example of a very complicated nice loop
http://forum.enjoysudoku.com/viewtopic.php?p=19181#p19181
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Thanks you, chopsuey!

Postby OldGeorge » Mon Mar 27, 2006 1:52 am

As an uninstructed solver who found the first few basic methods perfectly obvious, and then couldn't get beyond them for the 4-star (out of 5) puzzles in the Salt Lake Tribune, I've needed exactly the links in this thread.

So thank you for making it happen!
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