User talk:Oli Filth

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Brisk[edit]

I see that I have gained especial attention ("another of Nicky's overly-verbose additions"), and now you have purged a pile of stuff from the Interpolation_search article that lacked attribution to approved sources. Had you sought suitable sources? Even though this would require effort on your part, for instance by retaining parts for which you had found sources. Presumably, your high-level contributions will be applied impartially to other effusions of mine, as well of course to other persons. I had been contemplating reporting an actual comparison of the methods "linear", "binary" and "interpolation" on the same data file (coordinates of Arapawa Island, as it happens), but this would clearly be "original research" and so I hadn't bothered, even though examples are helpful towards comprehension. NickyMcLean (talk) 04:11, 5 June 2010 (UTC)

Yes, my edit summary was a reference to the fact that on at least a few articles that I've stumbled across (e.g. Self-modifying code, Binary search algorithm, For loop), the wordiest parts seem to be attributable to your edits. You of course know that phrasing such as that removed in my first edit is inappropriate for an encyclopaedia article. You are also of course aware that the original-research policy doesn't allow one to run a bunch of one's own experiments and then write what amounts to an essay on the results with no independent sourcing.
If sources for this material are really as easy to find as you imply above, then please feel free to add them yourself! I have no objection to this sort of content if it can be (a) sourced, and (b) written and structured appropriately. Oli Filth(talk|contribs) 09:07, 5 June 2010 (UTC)

"The generative fixation hypothesis" is back[edit]

I see you removed it here [1]. It has been added back here: Theory_of_genetic_algorithms. I'm mostly motivated by organizational issues and am concerned that the text for "The building block hypothesis" is copied en masse. But, I'm not really sure what to do with this other section about "The generative fixation hypothesis," since it seemed to be in dispute. What do you think? One simple option might be to just redirect Theory_of_genetic_algorithms back to Genetic algorithms. thanks, ErikHaugen (talk) 14:00, 14 June 2010 (UTC)

I've indeed created the redirect for now. If there's scope for Theory of genetic algorithms to have a raison-d'etre, and to contain material other than simple copy-and-paste, then perhaps it should be recreated. But not in its current state! Oli Filth(talk|contribs) 14:30, 14 June 2010 (UTC)
Exactly what I was thinking. Thanks, ErikHaugen (talk) 14:31, 14 June 2010 (UTC)
FYI, it's now been recreated; see the argument at Talk:Theory of genetic algorithms. Oli Filth(talk|contribs) 14:56, 14 June 2010 (UTC)

About the GFH[edit]

Dear Oli, I see that you've removed my recent edits to the genetic algorithms article on the grounds that it is "self promotion"? I'd like to get a sense for what you mean by this. Is it automatically "self promotion" when an author writes about his published work on Wikipedia? The generative fixation hypothesis is one of just two non-folk-hypotheses about the adaptive capacity of genetic algorithms (the other being the building block hypothesis). There is indeed a large body of "theory" about genetic algorithms; but, this work is best understood as "theoretical approaches to genetic algorithms"; apart from work related to the BBH and the GFH, none of it has, to date, produced a plausible explanation for the adaptive capacity of genetic algorithms. Another question: Eric Haugen writes above that the generative fixation hypothesis is in dispute. What are his sources? Keki Burjorjee (talk) 16:47, 14 June 2010 (UTC)

In general, editors who cite themselves (in particular, in cases of very new publications) are doing it purely as self-promotion. If that was not your intention, then I apologise for jumping to conclusions, but it's a very common pattern here at Wikipedia. If your work is notable (I have no idea; I don't claim to be anything close to a subject expert), then I'd prefer to see it referenced by other editors, because otherwise it raises questions of conflict of interest. I'd also prefer to see evidence of wider notability (i.e. has the notion of "generative fixation hypothesis" been picked up by others in the field? have your papers been cited?, etc.) Oli Filth(talk|contribs) 16:53, 14 June 2010 (UTC)
I understand your reservations. I believe that the generative fixation hypothesis is notable by virtue of being one of only two published, peer-reviewed non-folk explanations for the the adaptive capacity of genetic algorithms. It is also the only published, peer-reviewed explanation for the adaptive capacity of simple genetic algorithms with uniform crossover. —Preceding unsigned comment added by Keki Burjorjee (talkcontribs) 17:21, 14 June 2010 (UTC)
It would be nice to have this conversation somewhere else. Anyway, I disagree that it's notable because there are only 2 theories. It's notable when other reliable sources refer to it, etc. To be clear, I am not weighing in on whether it is notable; I am just discussing the criteria. ErikHaugen (talk) 17:32, 14 June 2010 (UTC)
Erik, that's certainly one criterion. But is it the only one? When evaluating the notability of a new, published, peer-reviewed theory, I believe that some additional points should also be taken into consideration---especially in a proto-scientific field like genetic algorithmics: i) the degree to which the new theory diverges from the prevailing theory, and ii) the potential impact on a field if the new theory turns out to hold water. Scientists sometimes take time to digest fundamentally new ideas. So, a new theory might not be cited immediately after its publication. Does that automatically make the new theory non-notable? The Generative Fixation Hypothesis is the first theory since the 1970s to give the building block hypothesis a run for its money. And, as I've previously mentioned, it is the only plausible explanation that has ever been proposed for the adaptive capacity of genetic algorithms with uniform crossover. I believe that removing all mention of this hypothesis from the genetic algorithm article does curious, seeking readers a disservice. Keki Burjorjee (talk) 04:58, 15 June 2010 (UTC)
Please see WP:NOTABILITY for the Wikipedia policy on notability. We can't just invent new criteria for protoscience. If this theory does have an impact on the field at some point in the future, then it will be cited, and then it will fulfil the criteria for notability. Until then, there's no need to mention it in the article. Doing otherwise really would be doing readers a disservice, because it would give a false impression of the notability of a particularly nascent school of thought. Please see WP:UNDUE. Oli Filth(talk|contribs) 08:17, 15 June 2010 (UTC)
I concede that my most recent edits may (kinda sorta) give the impression that the GFH is "equal" to the BBH in terms of adoption. Giving readers this impression was not my intention. I sought only to inform readers that there is an alternative to the BBH (a theory whose failings are well known), and to give a brief overview of the GFH. Nevertheless, I can see why you might view these changes as "overreaching". Would you be okay with rolling the article back to the point before my most recent edits? Another option is to let my edits stand, and to add a banner to the section on the GFH that cautions readers that the section contains material that may violate WP:NOTABILITY and WP:UNDUE. Keki Burjorjee (talk) 16:38, 15 June 2010 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── Well, the latter is certainly not an option! And to be honest, I'm not particularly keen on the former idea either. As far as I'm aware, your theories were published a little over 6 months ago, and have not yet been cited or discussed by any independent authors. The fact that you had to add them to Wikipedia yourself is indicative that they have not reached even the lowest rung of notability yet. This is not meant to be a criticism or a putdown; I'm merely pointing out that with the available evidence, there is no compelling reason to mention your theories at Genetic algorithm yet.

I would suggest that if you wish to continue to debate the issue, then bring it up at Talk:Genetic algorithm, so that a wider array of editors may air their opinions. Oli Filth(talk|contribs) 17:32, 15 June 2010 (UTC)

Six months eh? If only scientists were that reliable ;-)
I think you forget that you and Erik aren't the only policemen on this beat. There are others with domain knowledge greater than yours who would have removed, or contested my statements, and the reference to my dissertation if these were indeed unhelpful, or misleading. (My statements are provocative enough, and so is my dissertation) That neither have been removed, or contested for months should tell you something. In any case, I've raised the issue on the Talk:Genetic algorithm page as you suggested. I don't know how many people actually read that page without being prompted. Is there a formal procedure for getting some third party attention? Keki Burjorjee (talk) 06:39, 16 June 2010 (UTC)
Yes, see WP:3. However, it says "If more than two editors are involved, 3O is not appropriate." So I suggest you read through WP:DISPUTE to find a different approach.
By the way, don't be so sure that "no-one removed my edits" == "my edits were fine"! All sorts of inappropriate material (nonsense, vandalism, self-promotion, etc.) sneaks its way into Wikipedia articles all the time, and often sits around for months or years before anyone notices. The people that read the talk page are typically the people that "police" the corresponding article page, so if your guess that perhaps no-one will read that talk page without prompting is correct, that could also explain why some of your edits stuck around for a while. Oli Filth(talk|contribs) 08:48, 16 June 2010 (UTC)
Are you sure about that? I've done some deleting on Genetic algorithm myself (not enough, unfortunately), and can't say I've spent much time on the talk page. Thanks for the links. Keki Burjorjee (talk) 03:49, 17 June 2010 (UTC)
I did some digging. It turns out that your application of WP:Notability is incorrect. The nutshell box at the top of that page says "Notability does not directly affect the content of articles, but only their existence". I am not trying to set up a wikipedia page devoted to the generative fixation hypothesis; so, WP:Notability does not apply. It also turns out that a Ph.D. dissertation available on UMI (mine is) is considered a reliable source because it has been vetted by a committee of scholars. See the subsection on Scholarship in [2]. Up next, Conflict Of Interest. On Talk:Genetic algorithm you write "This was added as a COI edit; linking to one's own PhD thesis almost never acceptable!". You assume, in other words, that writing about one's own work is almost-by-definition a COI edit. The following sentence from Wikipedia:No_original_research#Citing_oneself says otherwise: "If an editor has published the results of his or her research in a reliable publication, the editor may cite that source while writing in the third person and complying with our neutrality policy". As mentioned previously, Ph.D. dissertations available on UMI count as reliable publications, and I do believe that I've abided by Wikipedia's neutrality policy. As mentioned previously, I agree that my most recent edits fall short with respect to WP:UNDUE. I'll figure out how to handle this better. In the meantime, I'd like to roll the section on the building block hypothesis back to its state in the following revision [3]. Any objections? Keki Burjorjee (talk) 07:06, 17 June 2010 (UTC)
In response:
  • You are correct about WP:N; however the criteria it sets out are, in practice, typically used as a benchmark for article content as well. If we didn't do this, it would be a free-for-all of people adding mentions to all sorts of non-notable research.
  • I never claimed that it wasn't a reliable source!
  • There's a difference between citing your own work to back up existing article content, and adding a section to an article about your own work. This is a case of the latter, and that is a conflict-of-interest. With respect, the fact that you are now fighting tooth-and-nail to get this reinstated is a further indication of COI.
  • As I've already said, unless you get some kind of consensus (basically at the thread you've set up at Talk:Genetic algorithm), there's no justification for adding this material back. If your work is truly worth mentioning at the moment, then let another editor bring it to the article (that's the spirit of WP:COI). Oli Filth(talk|contribs) 08:39, 17 June 2010 (UTC)
In response to your first point: You can't have it both ways Oli. Either we are both bound by Wikipedia's written policy, or neither one of us is. Whether or not there would indeed be a free-for-all is beyond the scope of the present discussion. If you feel that the spirit of WP:N does not match what's written in that article, you should take your complaint to its talk page. In my opinion, the sentence "Notability does not directly affect the content of articles, but only their existence" was given pride of place for a reason.
With respect to your third point:
  • Since when is engaging in a civil discussion, even a long one, an indication of misconduct? Aren't discussions like this supposed to make Wikipedia better? Your assumption that I've engaged with you here in bad faith is rather cynical. I'm actually enjoying this, and have learned quite a bit about Wikipedia and its policies.
  • If you follow the link I provided previously ([4]), you'll see that in the revision I want to revert to, the generative fixation hypothesis does not have its own section, and is mentioned in the Criticism of the Building Block Hypothesis subsection.
  • I misstated my objection to your sentence "This was added as a COI edit; linking to one's own PhD thesis almost never acceptable!". What I should have said is that an edit that violates WP:COI, while fraught, is not in and of itself bad. While the WP:COI article discourages conflict of interest editing, it does not forbid such edits, even at the article level: "Conflict of interest is not a reason to delete an article, though other problems with the article arising from a conflict of interest may be valid criteria for deletion." Wikipedia:COI#How_to_handle_conflicts_of_interest. This same section also has the following to say to editors dealing with conflict of interest edits: "Assuming good faith, start from the idea that the contributor was genuinely trying to help increase Wikipedia's coverage".
As far as I can see, the only rationale for barring me from mentioning my work is if you know that an impartial domain expert writing from a neutral point of view would not mention my work. Note: the domain expert is under no obligation to mention only work that has been cited. Since, by your own admission, you are not a domain expert, you aren't in a position to make this call.
So, I ask again, I'd like to roll the section on the building block hypothesis back to its state in the following revision [5]. Do you object? Keki Burjorjee (talk) 08:39, 18 June 2010 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── It's not about "having it both ways". "Notability" is not only a Wikipedia policy, but also a guideline that governs decisions about what's appropriate article content (along with common-sense, etc.). You're absolutely right when you state further down that "an impartial domain expert ... would not mention my work", at least in the context of this Wikipedia article, and at least in the context of today. That is because all content must be justified, and I'll say it again, there's no reasonable justification for mentioning a theory with no credence or acceptance in the field. Your theory is not even in the position where, for instance, it's been studied and rejected as invalid (even then it might be worth mentioning), it simply hasn't gained any exposure at all. Per WP:UNDUE and so on, Wikipedia should reflect this level of external coverage, i.e. none.

With respect to COI, please note that I'm not accusing you of bad faith; I'm suggesting that you're giving your own work undue importance. Why does your PhD merit mention in Wikipedia above the all the other hundreds or thousands that get written every year on the subject of genetic algorithms? If all we have to go on is your opinion that "this is the only plausible explanation for the capacity of genetic algorithms" (to paraphrase), then that's not good enough I'm afraid. That's where coverage by independent reliable sources would have helped.

So in summary, yes I would strongly object to rolling back, and I'd wager that if you started a request for comment, you'd get the same response from anyone else. In one sense, I suggest you do file a RfC if you want to carry this forward, because you aren't going to persuade me, and I guess you aren't going to persaude Erik either (not sure if he's following this or not). Oli Filth(talk|contribs) 09:03, 18 June 2010 (UTC)

Oli, your latest comments suggest that you are not just, as you put it, nowhere close to being an expert on genetic algorithms, you actually have little, if any, knowledge about the field. If you read my edits (and what I've repeated at different points in our conversation) you'll see that I've never said that the "generative fixation hypothesis is the only plausible explanation for the capacity of genetic algorithms". What I've said is that the generative fixation hypothesis [6] is, *to date*, the only plausible explanation for the adaptive capacity of genetic algorithms *with uniform crossover*. Do you understand the difference between the general class of genetic algorithms and the specific class of genetic algorithms with uniform crossover (UGAs)? Do you know that UGAs frequently outperform genetic algorithms with one point crossover, even though according to the building block hypothesis they shouldn't? Are you aware that since 1989, when the utility of uniform crossover was first highlighted, there has been no serious attempt to provide an explanation for the adaptive capacity of GAs that use this form of crossover, much less explain why they outperform GAs with one-point crossover? Do you know how deeply the Building Block Hypothesis, despite its shortcomings, continues to influence contemporary research in evolutionary computation? Do you understand the repercussions of any new theory that lays the building block hypothesis to rest? Can you appreciate why such a theory might not get cited immediately? Do you care to educate yourself about "details" such as these?
You seem to care more about justifying your use of one-size-fits-all instruments to mechanically decide whether an edit stays or goes---no matter what the article. Having settled on the existence of citations as one of your tools, you wield it in a heavy handed way, feeling little obligation to dig further. Are you capable of recognizing that there are limits to the kind of policing that one can constructively do with little to no domain knowledge? Keki Burjorjee (talk) 04:08, 19 June 2010 (UTC)
I did some googling. It turns out that papers of mine that became chapters 2 and 3 of my dissertation have been cited in two recent Ph.D. dissertations: [7], and [8]. Does this satisify you? Keki Burjorjee (talk) 06:32, 19 June 2010 (UTC)
You're right, I know next to nothing about genetic algorithms. But actually, that hardly matters. What matters is that I know how to edit Wikipedia articles. One does not need to be well-versed in the field to perform standard copyediting. Call it "heavy-handed" if you like, but requiring stuff to be independently covered in non-trivial detail (etc.) is one of the most powerful tools for preventing articles from filling up with unimportant details, self-promotion, hoaxes, etc.
The specifics of what your thesis are totally irrelevant from the point of view of writing an encyclopaedia article. I've already covered what is relevant. Arguments such as "why such a theory might not get cited immediately?" are also irrelevant; either something is notable and covered now, or it isn't. The latter does not preclude it from becoming notable and covered in the future; if it does, then that's when it will be time to think about discussing it in a Wiki article. Oli Filth(talk|contribs) 11:02, 19 June 2010 (UTC)
I reject your application of WP:N to article content, as does WP:N itself. Explicitly. At the top of the page. I have trouble understanding exactly which part of "Notability does not directly affect the content of articles, but only their existence" you don't understand. Wikipedia is not Citationpedia!
My goal is to improve Wikipedia for its readers, not to make it easy for you to do your chosen job. I wish you would recognize that there will be times when, as a non-expert, you won't be able to tell whether an edit benefits or hurts Wikipedia's readers. When this happens, it's okay to let others with more domain knowledge decide.
A question to ask yourself is what would have happened if Wikipedia had existed in the nineteenth century, and if in 1866, right after publishing his work on inheritance in pea plants, Gregor Mendel had made an edit about this work. Not as a separate article (that would violate WP:N), but within the main article on Inheritance. Something small, right after the section on blending inheritance and the troubles this (then dominant) school of thought was having explaining the existence of diversity in biological populations. Something like "Recently, a new hypothesis has been proposed that can explain the existence of diversity in biological populations. This theory is based on multi-generational experiments with pea plants. It holds that inheritance is particulate ....". Would such an edit have benefited or hurt Wikipedia readers? What happened, of course, is that Mendel's work went relatively unnoticed for 34 years, receiving only three citations during that time---all of them critical. It was nearly another two decades before Fisher, Wright and Haldane began weaving Mendel's work together with Darwin and Wallace's to give us the beginnings of the Modern synthesis. The Academy can be, and often is, stodgy. Wikipedia is a new frontier, in that it allows anyone to contribute relevant information that's in a reliable source. Please allow it to stay that way. If you don't dispute the relevance of my edits, and have no reason other than WP:COI to doubt my objectivity, kindly drop your opposition. Keki Burjorjee (talk) 05:46, 20 June 2010 (UTC)
Please don't trot out that analogy! New editors use it all the time, and the answer is always the same. It's very simple; Wikipedia doesn't give coverage to things that aren't yet covered by independent sources in non-trivial detail.
It's clear you have a problem with the applicability of WP:N. Perhaps you should re-read WP:UNDUE, and also WP:Fringe theories#Notability versus acceptance, which are essentially the application of WP:N to article content. They're the very antithesis of your notion that "Wikipedia is a new frontier", as the aim is for it to be the exact opposite. Oli Filth(talk|contribs) 09:51, 20 June 2010 (UTC)
I'm interested in learning if others in the Wikipedia community share your ideas about what Wikipedia is and is not. And, more to the point, if they agree or disagree with your judgement in this specific case. I'm going to submit an RfC. My question is the same as the one on the talk page of the GA article: Should the following statement be removed from the end of the "Criticism of the building block hypothesis" section? "Recently, a new explanation---the Generative Fixation Hypothesis---has been proposed. [*]". (I agree that anything more goes against the spirit of WP:UNDUE)
I certainly agree about Wikipedia not being a "new frontier" in this sense - the mendel example is good: his theories, as important as they were ultimately, wouldn't receive much treatment on wikipedia until they had achieved a certain level of notoriety. wp:FRINGE and WP:SELFCITING really seem more applicable here than wp:UNDUE, although I suppose all are relevant. (Not to denigrate your work with a label like "fringe," KB!) I think wp:FRINGE makes it pretty clear that a reliable source is good enough for inclusion, and completed dissertations are wp:RS. Personally, per wp:COI, I would wait until someone else did the including, although this is easy for me to say given the likelihood of me ever writing papers such as this - anyway not a hard requirement. I have no opinion about the case at hand, regrettably I know very little about the theory behind GAs. Heh - my main complaint was the article forking, so I am happy since [9]. Thank you both for your work on this page. ErikHaugen (talk) 06:30, 21 June 2010 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── Thanks for your comments Erik. With respect to the "new frontier" bit, my words were used out of context. My full sentence was "Wikipedia is a new frontier, in that it allows anyone to contribute relevant information that's in a reliable source". By this I mean that a single domain expert is unlikely to be aware of relevant information published in all the reliable sources of her field. An encyclopedic entry that she submits is therefore bound to be lacking in some way. Wikipedia allows anyone to fill the gaps as long as he or she uses information that's in a reliable source, and writes from a neutral point of view. It is in this respect that it is a new frontier. Oli, FYI, I've added the following revised "keep" argument to the talk page.

  • The generative fixation hypothesis (GFH) is one of only two published, peer reviewed, non-folk explanations for the adaptive capacity of simple genetic algorithms (the other being the building block hypothesis).
  • The generative fixation hypothesis is the only theory to date that claims to account for the adaptive capacity of simple genetic algorithms with uniform crossover (UGAs).
  • In practice, UGAs frequently outperform genetic algorithms with one point crossover, even though according to the building block hypothesis, they shouldn't. The GFH explains why. In doing so, the latter hypothesis addresses an anomaly that has been outstanding for over twenty years.
  • Given the above, a domain expert writing from a neutral point of view about genetic algorithms would be remiss if she did not mention the existence of the GFH; unless, of course, she finds a glaring fault with the GFH that was missed during peer review.
  • By his own admission, Oli Filth knows next to nothing about genetic algorithms. He is, therefore, not in a position to determine if a domain expert writing from a neutral point of view would or would not make the statement in question.

I have marked you as a reviewer[edit]

I have added the "reviewers" property to your user account. This property is related to the Pending changes system that is currently being tried. This system loosens page protection by allowing anonymous users to make "pending" changes which don't become "live" until they're "reviewed". However, logged-in users always see the very latest version of each page with no delay. A good explanation of the system is given in this image. The system is only being used for pages that would otherwise be protected from editing.

If there are "pending" (unreviewed) edits for a page, they will be apparent in a page's history screen; you do not have to go looking for them. There is, however, a list of all articles with changes awaiting review at Special:OldReviewedPages. Because there are so few pages in the trial so far, the latter list is almost always empty. The list of all pages in the pending review system is at Special:StablePages.

To use the system, you can simply edit the page as you normally would, but you should also mark the latest revision as "reviewed" if you have looked at it to ensure it isn't problematic. Edits should generally be accepted if you wouldn't undo them in normal editing: they don't have obvious vandalism, personal attacks, etc. If an edit is problematic, you can fix it by editing or undoing it, just like normal. You are permitted to mark your own changes as reviewed.

The "reviewers" property does not obligate you to do any additional work, and if you like you can simply ignore it. The expectation is that many users will have this property, so that they can review pending revisions in the course of normal editing. However, if you explicitly want to decline the "reviewer" property, you may ask any administrator to remove it for you at any time. — Carl (CBM · talk) 12:33, 18 June 2010 (UTC) — Carl (CBM · talk) 13:24, 18 June 2010 (UTC)

Implementation links[edit]

Hello Oli, could you please explain why are links to some (evolutionary algorithm) implementations inappropriate? When in a separate section, of course. These links were _very_ helpful to me at the time I was getting introduced to the field, and are still useful to some of my colleagues/students. I should mention that I only copied them from the previous 'External links' section. Regoc (talk) 07:23, 22 June 2010 (UTC)

MXR Page[edit]

Unless you have something valuable to contribute, why not just stay the hell out of there? You appear to know absolutely nothing about the subject. Thanks! --67.171.80.50 (talk) 20:07, 8 August 2010 (UTC)

  • I beg to differ. Drmies (talk) 04:16, 28 January 2012 (UTC)

Wikipedia:Mediation Cabal/Cases/2010-08-29/Genetic algorithms[edit]

I have offered to mediate this. Please indicate your acceptance or lack on the mediation page. Thanks. Hipocrite (talk) 14:27, 4 October 2010 (UTC)

Fourier Series[edit]

Hi, I see that you reverted my simplification of the Fourier Series page, because you feel that there is a significant difference between the sum of zero-phase sines and cosines, and the sum of arbitrarily phases sines. Ignoring the fact that you could have just added "and cosines" rather than reverting my entire edit - such that it still has an overly complicated "wikipedia pedant"-style introduction - can you explain this difference? They are mathematically identical. I.e. any sine wave with arbitrary phase is exactly equal to a linear sum of a zero-phase sine and cosine. 93.97.48.217 (talk) 22:48, 4 December 2010 (UTC)

Broadband[edit]

I noticed you commented on this a while back. It was a real mess so I took a little time to work on it. Only a start, but my idea is to try to balance between being technically correct but not bury the reader in jargon. I think the plan was to focus this article more on the original technical meaning (although wideband might be the place for that too?). But I thought I needed to mention a little about the new vague buzzword using by politicians and marketers. There are many of those articles than need to be cleaned up too, but time is short. Would appreciate any comments, e.g. is this the right direction? Do you have a good base reference, or a suggestion for a diagram maybe? W Nowicki (talk) 23:39, 13 July 2011 (UTC)

File:4 state TCM.png listed for deletion[edit]

A file that you uploaded or altered, File:4 state TCM.png, has been listed at Wikipedia:Files for deletion. Please see the discussion to see why this is (you may have to search for the title of the image to find its entry), if you are interested in it not being deleted. Thank you. Bulwersator (talk) 17:12, 31 August 2012 (UTC)

Examples of convolution[edit]

I saw the wiki page, but I couldn't find any examples using actual numbers evaluating the formula. Could you give some examples of convolution, please? Mathijs Krijzer (talk) 22:14, 9 March 2013 (UTC)

Definition[edit]

The convolution of f and g is written fg, using an asterisk or star. It is defined as the integral of the product of the two functions after one is reversed and shifted. As such, it is a particular kind of integral transform:

(f * g )(t)\ \ \,   \stackrel{\mathrm{def}}{=}\ \int_{-\infty}^\infty f(\tau)\, g(t - \tau)\, d\tau
= \int_{-\infty}^\infty f(t-\tau)\, g(\tau)\, d\tau.       (commutativity)

Domain of definition[edit]

The convolution of two complex-valued functions on Rd

(f*g)(x) = \int_{\mathbf{R}^d}f(y)g(x-y)\,dy

is well-defined only if f and g decay sufficiently rapidly at infinity in order for the integral to exist. Conditions for the existence of the convolution may be tricky, since a blow-up in g at infinity can be easily offset by sufficiently rapid decay in f. The question of existence thus may involve different conditions on f and g.

Circular discrete convolution[edit]

When a function gN is periodic, with period N, then for functions, f, such that fgN exists, the convolution is also periodic and identical to:

(f * g_N)[n] \equiv \sum_{m=0}^{N-1} \left(\sum_{k=-\infty}^\infty {f}[m+kN] \right) g_N[n-m].\,

Circular convolution[edit]

Main article: Circular convolution

When a function gT is periodic, with period T, then for functions, f, such that fgT exists, the convolution is also periodic and identical to:

(f * g_T)(t) \equiv \int_{t_0}^{t_0+T} \left[\sum_{k=-\infty}^\infty f(\tau + kT)\right] g_T(t - \tau)\, d\tau,

where to is an arbitrary choice. The summation is called a periodic summation of the function f.

Discrete convolution[edit]

For complex-valued functions f, g defined on the set Z of integers, the discrete convolution of f and g is given by:

(f * g)[n]\ \stackrel{\mathrm{def}}{=}\ \sum_{m=-\infty}^\infty f[m]\, g[n - m]
= \sum_{m=-\infty}^\infty f[n-m]\, g[m].       (commutativity)

When multiplying two polynomials, the coefficients of the product are given by the convolution of the original coefficient sequences, extended with zeros where necessary to avoid undefined terms; this is known as the Cauchy product of the coefficients of the two polynomials.

Insightful edits in 2008[edit]

FireV3.png

Thanks for burning the heresy in the Orthogonalization article. Unfortunately, you did not go forth to destroy its main source and the heretical article, as well as many links to it, persisted for five more years. Incnis Mrsi (talk) 09:50, 28 April 2013 (UTC)

Six years ago[edit]

...You added some text to the cycles per second article, the text saying that the change from CPS to Hz was "not without its critics". I'm removing that text today as it has been unreferenced this whole time. If you have a reference, feel free to restore the bit. Binksternet (talk) 16:14, 30 December 2013 (UTC)

AFD[edit]

Hi, Has anyone let you know that an article you created, List of EDGE networks has been proposed for deletion by other editors, and listed for deletion three times? - Just thought you'd like to know. Strawberrie Fields (talk) 16:53, 17 August 2014 (UTC)