## How are we solving the puzzles?

Advanced methods and approaches for solving Sudoku puzzles

### How are we solving the puzzles?

When I first started doing these puzzles about five years ago, (they were called by several different names and now Sudoku), along with others we solved them using plain logic. Now it seems one must know how to use algebraic content or just guess until a solution is found. Along with different programs people are using that allows one to use a hunt and guess system the fun of solving the puzzles has lost it's luster.
LimeyCliff

Posts: 6
Joined: 25 August 2005

You're still free to choose to solve these puzzles by plain logic.

As I understand it, Pappocom's puzzles are designed to be solved by plain logic alone. The only advanced method for these puzzles is x-wings, and that's only for Hard and above. However, you don't need to use even this technique if you don't want to.

If you've been solving for 5 years it seems to me that you will have developed your own method of solving that is successful for you and "if it ain't broke, don't fix it".

Just because there are solving programs out there and other, imho, mind-boggling, solving techniques, doesn't mean that you have to use them. Nor does it mean that you have to let them spoil your own solving.

Personally, I solve on paper and use logic alone (then again I haven't gotten up to Hard level yet). Pappocom's puzzles are definitely designed to be solved using plain logic alone and the program on this site - which is what I use to generate unique puzzles that I solve on paper - will provide you with such puzzles on every level up to Very Hard.

I can't speak to other puzzles that are avaliable as to whether guessing is required - Michael Mepham certainly advises guessing on his harder puzzles - and there are other puzzles available that have more than one solution.

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

### Solving puzzles

Luna,

I like the post you submitted in reply of my own post.

(You're still free to choose to solve these puzzles by plain logic.)

I do use logic but I was refering to other peoples choices.

(As I understand it, Pappocom's puzzles are designed to be solved by plain logic alone. The only advanced method for these puzzles is x-wings, and that's only for Hard and above. However, you don't need to use even this technique if you don't want to.)

I have no trouble solving the puzzles although I will admit that some take a long time.

(If you've been solving for 5 years it seems to me that you will have developed your own method of solving that is successful for you and "if it ain't broke, don't fix it".)

I do have my own method. In the last six months I have only failed to sole three puzzles. One of these I think is unsolvable.

(Just because there are solving programs out there and other, imho, mind-boggling, solving techniques, doesn't mean that you have to use them. Nor does it mean that you have to let them spoil your own solving.

I refer here to the plain old fashioned way of doing the puzzles.

(Personally, I solve on paper and use logic alone (then again I haven't gotten up to Hard level yet). Pappocom's puzzles are definitely designed to be solved using plain logic alone and the program on this site - which is what I use to generate unique puzzles that I solve on paper - will provide you with such puzzles on every level up to Very Hard.)

True.

(I can't speak to other puzzles that are avaliable as to whether guessing is required - Michael Mepham certainly advises guessing on his harder puzzles - and there are other puzzles available that have more than one solution. )

Guessing is strictly a NO NO and I do not try to solve his puzzles any more
Due to that reason

Luna

Thanks for your time. Hang in there and you will find that the challenge of the harder puzzles is a wonderful experience in puzzle solving.

Cliff
LimeyCliff

Posts: 6
Joined: 25 August 2005

You're talking about apples and palm trees. One person can certainly enjoy one, neither or both.

I've done puzzles all my life. I've solved "Number Place" in Dell Magazine -- which were much too easy, and then "Sudoku" Nikoli and other Japanese magazines for many years. The difficulty level for Nikoli-type Sudoku was such that a reasonably experienced person can solve them using the fairly small-sized printed grid. The very hardest might require writing 2 or 3 pencil marks in the remaining cells near the end of the puzzle. They simply do not make puzzles that require 90% of the methods discussed here -- and if fact, these methods would nearly always be useless on those puzzles.

After solving a few hundred of these over the years -- I was done. There simply wasn't any reason to keep doing them for me. They became no more challenging or interesting than a wordsearch puzzle. That is, in the end, all there was to do -- search for which cell, at this point, can contain a single number, or search for which number can be restricted to a single cell -- and once in a while, there might be something every so slightly more complicated like two cells in a row that both can contain the same to digits. The only difference between the easy ones and the hard ones is the number of cells at a given time that can be filled. Any feeling of being clever was long since past. I had mastered the puzzle and therefore had no use for it.

For many years, up until the recent Sudoku boom, the only Sudokus I would do in the Japanese magazines were the variations, the overlapping ones, the sequentials, etc. See this post. But mostly, I moved on to other types of logic puzzles that I hadn't mastered yet.

The "Very Hards" created by Pappocom's software are somewhat more difficult that the hardest ones published in Japanese magazines, which seem to top out at "Hard". (A few papers publish puzzles that are somewhat beyond this level -- and although their compliers might tell you that guessing is required, it isn't.)

Anyway, the point is, that when you're putting out magazines with 100-200 puzzles, when your target audience wants to solve the puzzle directly in the book, newspaper or magazine, there is little incentive to include puzzles that would require people to do the things that have been talked about in these forums. (For example, when the LA Times started printing Sudokus, they included "Diabolical" level puzzles that were beyond the level of the most difficult Pappocom -- but apparently readers complained. Now, though they still *label* them as "Tough" and "Diabolical", all the puzzles are what Pappcom would call Very Easy, Easy or Medium.) They are really two completely different experiences.

There are puzzles that simply cannot be solved by the same methods we use to solve the puzzle published in newspapers or made by Pappocom. This does not make them invalid (regardless of what Wayne says) nor should you infer that those of us who try to solve them with a variety of new methods and ideas are ruining the experience for ourselves. I can still sit down in the morning and enjoy solving the Sudoku in the paper -- it simply has *nothing* to do with trying to solve the very, very hard ones. There is a great deal of fun in exploring what seems to be uncharted territory, discovering new levels of complexity and techniques for unraveling them. Finding the tools that work can be more rewarding than simply using the tools over and over. Describing them in terms of difficulty level is misleading -- they really are different puzzles with different challenges. One verh well find it easier to apply some advanced techniques when required than some of the basic techniques.

There's a fractal nature to it all. At one point, the consensus is that puzzles beyond a certain level or of a certain structure cannot be done by humans. Then some new ideas are put forward, and suddenly, the bar is raised. But because the total number of possible puzzles is astronomical, and advanced levle puzzles can be created at will with software, the challenge remains intact -- there are always an unlimited number of puzzles just beyond our current capability (as well as far beyond).

So there is no reason to worry that some of us are "missing out" some way. Nor is there any reason to feel that you have to partake in all facets of this Sudoku. Look at it this way. I play chess. Gary Kasparov plays chess. There is simply nothing similar to what he does and what I do. The pieces *look* the same, the board is the same shape -- but our games are *absolutely* unrelated. His vast knowledge means that he probably won't enjoy a game with me -- my meager skill means I won't understand a game with him. And yet, we both keep playing. The only thing that keeps us playing is that we know we can keep pushing our level of play forward, find new things, etc. The day I believe that isn't true is the last day I play chess.
tso

Posts: 798
Joined: 22 June 2005

tso wrote:There are puzzles that simply cannot be solved by the same methods we use to solve the puzzle published in newspapers or made by Pappocom. This does not make them invalid (regardless of what Wayne says) nor should you infer that those of us who try to solve them with a variety of new methods and ideas are ruining the experience for ourselves.

Absolutely agree tso- and very well put. Pappocoms solving algorithms are without a doubt also put to use in the creation of his grids- so it follows that if a grid is created without recourse to these algorithms, it may not be solvable BY them, (there may also be duplicate solutions) - but it doesn't make the 'outlaw' single solution grids invalid.

This raises the possibility that out there somewhere is the grandaddy (Pappa?) of all solution / creation algorithms that encompasses every technique that has been developed so far.... now THAT's something to work on.

stuartn

stuartn

Posts: 211
Joined: 18 June 2005

I'd just like to make myself perfectly clear.

At no time have I ever said that anybody couldn't or shouldn't use the advanced solving techniques described on this forum or that it was wrong to do so. As for inferences that it spoils someone else's pleasure, well that's in the eye of the beholder. I was replying to LimeyCliff's original post where it seemed to me that he/she thought that they were necessary, imho they are not.

As for myself, these advanced techniques do look mind-boggling to me, then again perhaps I'm not that algebraically advanced. As stated before I've never gotten beyond Fiendish level and if it means learning a whole host of complicated techniques, I'm not sure that I want to. However, that is my perspective and doesn't really involve anybody else.

I have, elsewhere on this forum, stated that it's up to the individual to choose the challenge that suits them.

Questions about software algorithms for the Pappocom program need to be addressed, imho, to Wayne - he did write it after all.

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

"On how to sing
The frog school and the skylark school
Are arguing."

Shiki, Haiku
emm

Posts: 987
Joined: 02 July 2005

Excellent summary tso, thanks.

Aaahh stuartn, the search for the infinite...

em, lovely Haiku, try this one:

"Yesterday it worked
Today it isn't working,
Windows is like that."
Karyobin

Posts: 396
Joined: 18 June 2005

luna wrote
Questions about software algorithms for the Pappocom program need to be addressed, imho, to Wayne - he did write it after all.

back to the cricket.

stuartn
stuartn

Posts: 211
Joined: 18 June 2005

Regarding tso's and Luna's excellent comments, and chess: Computers have now, under certain conditions, vanquished even Kasparov, and the "perfect game" may be not far off. I still play, at my level, but perhaps with just a twinge of regret that it's come to this.
Doyle

Posts: 61
Joined: 11 July 2005

Not love affairs:
naked pairs and XY wings –
and yet puzzling.
emm

Posts: 987
Joined: 02 July 2005

Top stuff em. Deep.

"The Web site you seek
cannot be located, but
countless more exist."
Karyobin

Posts: 396
Joined: 18 June 2005

Stuartn wrote:

Exactly.

It seems to me that the only person who can say
Pappocoms solving algorithms are without a doubt also put to use in the creation of his grids......
would be Wayne Gould, who wrote the algorithms you mentioned. And if you didn't ask him .....................

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

From the programmers forum April 2005.

Wayne Gould wrote:

You can set Su doku puzzles “by hand”, if you want to, though I haven’t done it much myself. You use much the same skills you do when solving a puzzle, but backwards.

Luna - I don't need to ask - but thanks for your interest.

stuartn
stuartn

Posts: 211
Joined: 18 June 2005

Stuartn

Setting puzzles by hand is wholly different to writing alogorithms for a computer program to create (or that matter solve) the puzzles.

Luna
lunababy_moonchild

Posts: 659
Joined: 23 March 2005

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