h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

http://www.h2g2.com/A444845
Is this an entry worth to be included in the Edited Guide?
I'd like to see your comments ... /click/... see your comments ... /click/ ... see your comments ... /click/ ...

hmmm, seems hard to get some attention here !?

This is a reasonably interesting article, but it it didn't really grab my attention. Still, I'm just one reader. A few points:
why do you think Bill Murray experienced Groundhog Day only 42 times? Did you count? I got the impression that by the end, he had been over it maybe 50,000 times!

You might like to say something about the mathematics of proving that a program is in an endless loop. If you can always prove that a program will or will not go into an endless loop, then you can prove all mathematical statements by a mechanical process. This is known as computability and is a large area of mathematics.

As to the Groundhog Movie: the people from the movie database did the counting and a lot of logics as well (figuring out that lunches are commonly separated by midnights and such). They arrived at 42 loops, but of course, viewing the movie leads to the impression of an infinite loop.
My intention, rather than maths and proofing, was to do some 'philosophy' on endless loops, as the second para said:
There are different levels of endless loop situations, and this is what this entry is all about.

Please don't take this the wrong way, but there was something about this entry that just put me off. I don't know if it was the topic, the writing, or just me not having a good day - but there was something that didn't sit well with me...

Anyone else?

Hello,

In regards to computability, Turing actually proved that it is impossible to create a standard program that can tell you whether or not any other given program completes (this is known as the halting problem). So it's mathematically impossible for a computer to really detect it's ever in a loop.

Otherwise, I think this article could be worked in a different direction. Besides bad looping conditions (not all of which are truly endless), there are a bunch of good or neutral loops that appear in mythology, science, and such:

1. The cycle of reincarnation
2. The water cycle (evaporation->rain->rivers->ocean->evaporation).
3. Positive and negative feedback (the positive makes that noise; the negative is cybernetic control).
4. Other notions of cyclical time (eg, the Mayan calendar)
5. The earth going in orbit around the sun (the seasons)
6. The snake eatings its own tale wrapped around the earth (Ourobouros)
7. and so on...

But whatever, just a random idea...

Yours,
Jake

hey, you know what you've done? You destroyed part of my worldpicture!
I always thought there were only 'negative' endless loops....
This sends me into an, err, thinking process, hope I'll come up with a more balanced view.
Thanks for that!!!

Hello,

Despite it's name, negative feedback (so called because it reduces instability) is one the most positive loops in existence. It's what allows you to move your muscles, control your thermostat, keeps natural populations in some balance...

It's an interesting idea. You could have a positive and negative loops article.

Yours,
Jake

Hello,

Incidentally, somebody needs to write a good article about Recursion (while we're on the topics of loops). There are some 6 articles that match a search, and all of them are the same stupid joke (which is funny as an intro, but pretty dumb as an entire entry).

Yours,
Jake

I was thinking of that, but failed to think of an example more expressive than DOS directories and the x! (facultative, sp?) function.

Hello,

Good thinking. The factorial (x!) is a fine example (you can describe it in both iterative and recursive forms). Of course, this brings up an interesting point about there being potentially two other different types of loops: iterative and recursive (or self-referential). But they are probably equivalent in some way.

Recursive Acronyms seem to be the rage among open-source programmers these days. For instance, GNU stands for "GNU's Not Unix", and the GIMP is "GIMP Image Manipulation Program."

Yours,
Jake

indeed, the iterative factorial solution is even more efficient in terms of calculation steps.

Because my computer broke down this morning (I`m writing this from an internet cafe), I`m afraid it`ll take some time to continue working on the entry. The Writing Workshop seems to be a better place for this conversation

Ok folks, I've given it some polishing now and also tried to make it a more balanced thing. I'm not sure whether to include feedback loops as well: they /are/ loops, but I fail to see the 'endless' aspect. What are your thoughts, please?

Feedback loops can be endless or not, depending on wether anyone stops them or not, but the same is true of the examples in the entry. Probably almost any kind of loop is potentially endless.

I think it is confusing to refer to 'positive' and 'negative' loops when the same words are used for the very different ideas of feedback loops. Maybe find another way to phrase it.

Another 'good' example of endless looping: mathematical induction - you show something is true for the number 0, and you show that if its true for a number n, then its true for n+1. Then the argument loops endlessly to show its true for all natural numbers. Its also covered in http://www.bbc.co.uk/h2g2/guide/A387470 (Basic Methods of Mathematical Proof).

Self reference (http://www.bbc.co.uk/h2g2/guide/A508754 , though the link will change if/when it gets edited) often leads to endless loops, so a couple of recipricol links should lead to a 2 step endless loop .

Another 'bad' example - vicious circles. Well, you've sortof mentioned them, but not by name.

About the dripping tap - some of the insanity of it is when the dripping *isnt* entirely regular. With the right flow of water, the periods between drips is chaotic. Its possible to sleep with a clock ticking in the background, because the brain works out the pattern and decides that since it isn't changing from the pattern, its not something to worry about. With a chaotically (what?!? theres no entry on chaos !?!) dripping tap, the brain keeps trying to find the pattern, and fails, keeping you awake all night.

Ok, I gave it another polish and took out the sarcasm (I hope)

Does that sound better now?

Couple of things:

"This circuit fired just now, didn't it?"

Maybe I'm just not getting this, but I couldn't see where the line before had been repeated (if that was supposed to be the point?)

07pm should be 7pm.

I think less use of the might help - looks sortof choppy and unformatted when I view it with long lines (ie a wide browser window).

I'm not sure you can do internet providers: the loop does end, if you run through it enough times, so it's not terribly endless. Whereas dripping taps are endless, if you don't do anything. The first has an end, the second is *potentialy* endless. Oh, and you could link to the edited entry on dripping taps...

Ditto chasing flies - if you repeat it enough times you'll kill the thing: it's not even potentially endless.

Dripping Water II - this is also known as the "Chinese Water Torture"...

Reincarnation - you can get reborn into a worse place as well as a better place. It's also not clear that this in inherently good or bad - some religions see reincarnation as an endless extension to suffering... maybe you need a new section for "indifferent endless loops".

You could mention perpetual motion machines, and their impossibility. It seems related.

Well, well, I've given it another attempt ...

IMHO, 'endless' is to be seen as the subjective perception of the situations in question, otherwise there weren't any at all, even computers have ends to their lifes.

If there aren't any 'scouts,' then this peer revue process could be another form of endless loop. We keep suggesting, you keep improving, and waiting for Godot . . . erm . . . the scout to come and pluck you from this self-inflicted purgatory. (Not hell. Hell would be if you have been told there are no scouts and that you must keep on writing till a scout shows up.)

And don't show up here and claim to be a scout if you aren't going to end this endless loop.

I admire your observation that man has an inbuilt mechanism to avoid loops. That man is a pattern using and pattern recognizing creature is something that is often said, but I have never heard your corollary before.

You are covering the ground here but I would like to see it a bit better organized. If it is at all possible, it would be nice to generalize about good and bad loops (or desireable and undesireable; which might serve better than 'good' and 'bad.') as a basic observation about the nature of life, the universe, and everything before proceeding to break these loops into types and degrees of their favorable and unfavorable natures.

If you must use 'good' and 'bad' then please touch on the philosophically ultimate good and bad loops called Heaven and Hell.

(". . . For who would fardels bear, to sweat and grunt under a weary life, but that the fear of something after death, that undiscovered country from whose bourne no traveler returns, puzzles the will and makes us rather bear those ills we have than fly to those we know not of?" "Now, now, Master Shakespeare. How many times must I tell you not to end a sentence with a preposition? Now let's talk about your word choice . . ." Shakespeare's hell.)

It would also help, IMHO, if you could generate some sort of pseudo-scientific or German philosophical classification system that ranks these things as if they were exact quantities. Or, maybe I'm just projecting the way that I would have approached your topic, if I'd had the good sense to think of it.

I like it but I think you can do it better, Master Bossel.

Barton