A couple of questions by a newcomer.

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A couple of questions by a newcomer.

Postby Thedutchguy87 » Fri Apr 27, 2018 4:20 pm

Hello everyone,

I'm a long time sudoku enthusiast, and after some time wandering the internet I've ended up here. I've tried reading up on old topics and discussions, but due to the age and size of some threads sometimes it can be like an archeological excavation. So I figured i'd just ask :) . Just for clarity it might help to give a little background into my solving: I use AIC's allowing grouped and ALS nodes. For especially hard puzzles and whenever I happen upon them I also use Denis Berthier's Z and T extensions.

Anyway, here goes:

1. I've come to frame every technique I found as an AIC subset. I feel like I miss eliminations that could be achieved through APE or ALS type moves as they're sometimes hard to see as AIC (or impossible to be seen as such maybe?). I'd like to hear from people experienced in applying these techniques on how to find and combine ALS's suitable for trail.

2. I've come across the terms "eureka" for documenting moves, and "GEM" for marking up candidates. But I'm having difficulty finding the rules to both, does anybody have direct link?

3. People here seem to use sudoku explainer to rate a sudoku's difficulty, the software must still be around, but the link provided in multiple threads is dead. Is there a mirror I could use?

I hope to hear from you guys, and participate more in these forums.

Have a good one,

Dutch.
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Re: A couple of questions by a newcomer.

Postby Leren » Sat Apr 28, 2018 1:29 am

A link to Eureka notation on the Sudopedia mirror site is here.

A link to ALS moves on the Hodoku site is here here and on Andrew Stuart's site is here.

All three sites contain a wealth of information in a format that is more easily digestible than this site, and all are worth thoroughly exploring.

Leren
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Re: A couple of questions by a newcomer.

Postby Thedutchguy87 » Sat Apr 28, 2018 7:32 am

Leren wrote:A link to Eureka notation on the Sudopedia mirror site is here.

A link to ALS moves on the Hodoku site is here here and on Andrew Stuart's site is here.

All three sites contain a wealth of information in a format that is more easily digestible than this site, and all are worth thoroughly exploring.

Leren


Thanks you for the links Leren!

I had seen hodoku before, but never really dug into the documentation there. I'm going to check it out again! As for the sudopedia link on eureka, exactly what I was looking for :). Should help me decipher some more of this forum. Lastly, I know stuarts site and solver well, I've learned most of what I know there.

I'm still looking for the SE software, and how The GEM markup works. If anyone who happens to read this can help me, I would much appreciate it.

Thanks again Leren for your reply.

Dutch.
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Re: A couple of questions by a newcomer.

Postby rjamil » Sat Apr 28, 2018 1:22 pm

Hi Dutch,

As far as your question #3 is concern, please note that gsf site contain slightly modified required file.

If you are interested in lKsudoku's SudokuExplainer Fixes then read this post and/or download directly from his google site.

R. Jamil
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Re: A couple of questions by a newcomer.

Postby Thedutchguy87 » Sun Apr 29, 2018 10:35 am

rjamil wrote:Hi Dutch,

As far as your question #3 is concern, please note that gsf site contain slightly modified required file.

If you are interested in lKsudoku's SudokuExplainer Fixes then read this post and/or download directly from his google site.

R. Jamil


Thank you Rjamil! I'll look into this when I've got the time.
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Re: A couple of questions by a newcomer.

Postby StrmCkr » Sun Apr 29, 2018 4:18 pm

"GEM" for marking up candidate


the only software that i know that does this is made by David.p.bird
and its a spreed sheet/ visual basics thing.... and not public access TTBoMK.

its a fanciful way of marking all the weak/strong link connections that a chain would make for keyed digits on a specific target cell.

going in both left and right directions following Parent-> offspring relation ships.
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Re: A couple of questions by a newcomer.

Postby Thedutchguy87 » Mon Apr 30, 2018 8:14 am

StrmCkr wrote:
"GEM" for marking up candidate


the only software that i know that does this is made by David.p.bird
and its a spreed sheet/ visual basics thing.... and not public access TTBoMK.

its a fanciful way of marking all the weak/strong link connections that a chain would make for keyed digits on a specific target cell.

going in both left and right directions following Parent-> offspring relation ships.


Thanks StrmCkr,

I wasn't aware it was a software based system, from context I assumed it was a method that could be used on paper. The two don't exclude each other of course, in case it is still a method that can be used on pen and paper I'm keen learn more about it.

I also think I should have posed my question better. In this case I was interested in the system because the way I mark candidates/links seems clunky. What I do now is the following (for clarity, I like to solve on paper) :

1. I eyeball as much as I can starting with boxes/pointing pairs, following up with rows and columns. Using any obvious structures along the way.

2. Just mark any leftover candidate/clue in a cell with a pencil, and make 9 (less if a certain digit is done or in a closed network of strong links already) mini grids on another piece of paper where I mark all instances of 1 through 9 and draw strong links.

3. I then check for naked/hidden sets, and obvious uniqueness. After this I turn to my mini grids and look for single digit patterns.

4. If the puzzle isn't cracked by this point I just go ham with AIC's starting wherever, keeping track of eliminations on the main puzzle and in my mini grids if I feel like it.

Writing this out for the first time actually clarifies the issue for me a bit. The GEM question rephrased would be: Is there a more efficient way of marking up candidates/strong links? (and additionally should I bother with weak links in any way?). Secondly, is there a more efficient global procedure? I realize there are a lot of ways of doing this, and it could well be mostly a matter of personal preference. But I'm still very much interested in additions, critiques, and alternate approaches.

If anyone feels like giving their two cents it'd be much appreciated.

Dutch.
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Re: A couple of questions by a newcomer.

Postby David P Bird » Mon Apr 30, 2018 10:31 am

This is the <GEM write up>

It was designed to be used on a spreadsheet using conditional colouring to highlight where a focus digit would be true or false as a chain is followed.

It only follows chains that emanate from a starting link so using pencil and paper either requires the marks to be erasable or several copies of the grid to explore different openings. It also takes quite a lot of practice to master as a simple marking error can lead one on a merry dance.

A useful side grid for manual solvers is the b/b plot which shows the bilocal digits in houses and bivalue cells. For example enter the bilocal digits directly in the side grid cells and circle the cells that contain bilocals bivalues. This then gives a map of the primitive strong links that exist.

DPB
Last edited by David P Bird on Mon Apr 30, 2018 2:16 pm, edited 1 time in total.
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Re: A couple of questions by a newcomer.

Postby StrmCkr » Mon Apr 30, 2018 1:48 pm

Thanks dpb. By the way the name is the link in my above post is the same one you provide....

Yes it was designed for manual solvers in mind as additional markings
However, it's biggest difficiences is you have to either have mutiple copies of the same puzzle (81*9) if you wanted to trace every cell... Or do alot of erasing as following diffrent numbers from diffrent cells would leave the same markings everywhere = confusion and a lot of dead-end.

But it can be done, easiest to use in software form.

Cheers
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Re: A couple of questions by a newcomer.

Postby Thedutchguy87 » Tue May 01, 2018 11:18 am

David P Bird wrote:This is the <GEM write up>

It was designed to be used on a spreadsheet using conditional colouring to highlight where a focus digit would be true or false as a chain is followed.

It only follows chains that emanate from a starting link so using pencil and paper either requires the marks to be erasable or several copies of the grid to explore different openings. It also takes quite a lot of practice to master as a simple marking error can lead one on a merry dance.

A useful side grid for manual solvers is the b/b plot which shows the bilocal digits in houses and bivalue cells. For example enter the bilocal digits directly in the side grid cells and circle the cells that contain bilocals bivalues. This then gives a map of the primitive strong links that exist.

DPB


Thank you David for the clarification.

As I'm adamant (for the moment) to stay on paper, I'm going to try the b/b plot you suggested. It should be better than my 9 mini grid approach.

Thanks again for all your input guys,

Dutch.
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Re: A couple of questions by a newcomer.

Postby SpAce » Thu Jun 14, 2018 8:56 pm

Thedutchguy87 wrote:As I'm adamant (for the moment) to stay on paper,

Cool. Not many of us around, I guess.

I'm going to try the b/b plot you suggested.

I wouldn't recommend that. A full b/b plot (the way I understand it) is way too cluttered to be useful.

It should be better than my 9 mini grid approach.

I don't think so. The single-digit grids will help you much more than a b/b plot ever could, even though (or because) they have less information. They're invaluable for finding single-digit patterns and chains, even if you have a good replacement for b/b plots, so don't give up on them. They're just not enough for finding 3D AICs, so you need other tools as well. For me the single-digit mini grid is usually the first level of escalation if I feel I need more help after completing my main grid mark-up (which has the power of b/b plots but with less clutter).

The GEM question rephrased would be: Is there a more efficient way of marking up candidates/strong links?

I'm not sure if I understand the question. How do you define "efficient"? If you want to solve a non-basic puzzle as quickly as possible without computer aids, I'd say GEM is about as efficient as it gets (if you know how to use it efficiently). I just don't see it as a general way of marking up candidates and strong links, so your question seems moot to me. GEM is a coloring technique, and very efficient and effective at that.

I have created a comprehensive way of marking up candidates and strong links, but I don't see it competing with GEM at all. My system provides visual aids for following links by eyeballing but it's still the player's responsibility to find the useful chains. GEM, on the other hand, finds eliminations/contradictions directly, from which you can then deduce the chains/nets responsible for them. Mine is a direct replacement of b/b plots but GEM isn't -- mainly because the results of the latter depend on the chosen seeds, i.e. you may need several GEM mark-ups to get the full picture.

Personally I think GEM is an awesome technique when really needed. However, I think it's over-powered for most normal sudokus because it takes away the joy of finding useful chains on your own. Then again, it's a very nice trick to have in your toolbox for harder puzzles when your own eyeballing no longer produces results (or if you want to solve faster, or if you're just learning to find chains). I have created a quick way to use GEM with pencil and paper, so it certainly does not require software helpers. I personally use GEM as a last resort method, but I'm not saying it's the only way to use it.

(and additionally should I bother with weak links in any way?).

Generally, no. You need to be aware of them, especially with XY-Chains and other ALS chains, but marking them all up would produce too much clutter (like the full b/b plot). Concentrate on identifying strong links and learn to imagine the weak links between them. In some helper grids with just subsets of the candidates (e.g. bivalues, single digits) it may be useful to mark the weak links as well.
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Re: A couple of questions by a newcomer.

Postby ghfick » Sat Jun 16, 2018 11:53 pm

Here is a link to a thread about yet another way to mark up :
i-am-primarily-a-pen-and-paper-solver-t33078.html
I must also strongly recommend David P. Bird's JE Compendium :
jexocet-compendium-t32370.html
And also David's documents on MSLS and SK Loops :
using-multi-sector-locked-sets-t31222.html
domino-loops-sk-loops-beyond-t32789.html

Best
Gordon
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