User talk:Maelin

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Hello, Maelin, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Where to ask a question, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! 

Freerunning article[edit]

Hi, well done on raising the free running article on the cleanup page. As I mentioned there, you are right, the choice of templates in cases like that is difficult. However, cleanup is a bit of catch-all template, but that also means it gets massively over-used. The thing to remember is to be bold and try and fix things - templates are useful, but someone fixing an article is more preferable. Some options are to copyedit it to improve it, research the subject and expand it or nominate it for deletion. In this case free running is actually another name for Parkour, which already has a good article. So, I suggest you edit the article to redirect it to parkour - I'll leave it for you to do as its a useful one to learn - see Wikipedia:Redirect for instructions. Drop me a note if you have any questions about anything. Kcordina 12:04, 1 March 2006 (UTC)

Forgot a couple of things - when redirecting, make sure you don't create any double-redirects. Here you'll notice that freerunning redirects to free running so you'll need to also change the freerunning redirect. Also, its a good idea to leave a note on the articles talk pages stating why you have made a change such as redirecting (which, hopefully, isn't "because kcordina told me to!). Kcordina 12:08, 1 March 2006 (UTC)


Thanks. Dr.K. 13:46, 30 July 2006 (UTC)

Thanks for the reply to my query on the 0.999 article talk page. ShaiM 07:54, 23 October 2006 (UTC)

Re: Troll warning[edit]

Hi, I've replied at my talk page. -- Meni Rosenfeld (talk) 11:09, 31 October 2006 (UTC)


JL continues to "fail to respond to any post that might seriously challenge [his] claims" and "fail to read the articles we repeatedly direct [him] to." Why continue to explain these things to him, spoon-feeding him information to reward his bad faith? I decided — and I believe Meni decided — to stop responding to his mathematical posts and his insults. Perhaps he'd see lack of response as an admission that he was right all along, but better to have one deluded person than a garbage talk page we spend untold hours updating. Calbaer 20:14, 14 November 2006 (UTC)

Please vote on attempt to delete new Ref Desk rules[edit]

Vote here: Wikipedia:Miscellany for deletion/Wikipedia:Reference desk/rules. StuRat 02:06, 13 December 2006 (UTC)


Ok i nominated the article. the discussion for deletion page is up. its been 5 days. i read the page on wikipedia about articles for deletion but still am not sure what to do. what do i do now?Missy1234 15:47, 21 December 2006 (UTC)

No worries now, that article i nominated has been deleted.Missy1234 00:13, 27 December 2006 (UTC)missy1234

"Endless Deletions"[edit]

I'm not really sure what you want me to say. You open with the claim that you are not merely trying to plead for pet articles and that I should consider carefully what you say, but then proceed to accuse me of being irrational, acting in bad faith, and having some kind of personal antipathy towards amateur game designers.

The answer is that I sincerely feel that notability is an important, even crucial, policy on Wikipedia, and it is the one that gets stretched and distorted most often. People often lose sight of the fact that Wikipedia is an encyclopedia, not an indiscriminate collection of information. Frankly, articles on non-notable personages like Mr. Croshaw just make Wikipedia look bad, and the problem is particularly acute within the computer and video games topic area, under the jurisdiction of the WP:CVG project.

These people and their amateur adventure games simply aren't worthy of inclusion in a general purpose reference work. They are not notable; not in the broader view of the term (which would probably exclude quite a few commercial video games, but it's a slippery slope) and not in the narrower sense, within the computer and video gaming community.

Before I read of them on Wikipedia, I had not heard of any of the games or game designers I have proposed for deletion. Prior to the actual deletion debates, I had never met or spoken to Ben Croshaw, Dave Gilbert, or any of the designers, creators, or fans of the games I have endeavored to delete. (Several of them did talk to me since then, and I also participated in a debate-cum-flamewar on Croshaw's message board.) I do not harbor any resentments toward any of the subjects of pages that I have taken it upon myself to submit to AfD. My deletion proposals are attempts to cleanse Wikipedia of non-notable, non-encyclopedic content, and nothing more.

As for 0.999..., we can discuss this further if you like, but I get the impression that it wasn't particularly a focus of your message. In a nutshell, I think that it is a particularly egregious violation of the purpose of a talk page, and that it probably provokes more inappropriate discussion just by its presence. Andre (talk) 14:58, 11 January 2007 (UTC)

Oh, and I prefer to keep my discussions fragmented (in other words, I won't post on my own talk page). If you like, you can delete this from your own talk page, but please don't copy it to mine. Andre (talk) 15:00, 11 January 2007 (UTC)

Ref desk question[edit]

I have been vaguely following the discussion of the module isomorphism problem at the ref desk. The key reason why the kernel of the action stays the same under the module isomorphism is that these isomorphisms have the property φ(rx) = r φ(x). If you find the action concept hard to work with, you can just think of the homomorphism f from R to R/I defined by f(r) = r + I = r(1+I). The isomorphism then maps this to r + J, which is the same as the canonical homomorphism from R to R/J. Hope this helps, nadav 09:53, 14 May 2007 (UTC)

Homology (from Ref Desk)[edit]

I thought we should move this away from the Ref Desk. Although I'm trying to concentrate on writing about homotopy groups of spheres, maybe I can help a little more with your homology.

Suppose we have an icosahedron, thought of as a spherical surface busted up into triangles. As far as topology is concerned, it doesn't matter if the triangles are flat or projected out onto the curved surface of the sphere. This is the idea of a simplex and of a chain, to "triangulate" a space. The sphere is an "orientable" surface, which is a concept we can translate into triangles (simplexes). We can order the vertices of each triangle so that a perpendicular to each points outward by the right-hand rule. A simple test is to look at edges; the edge between two vertices of the icosahedron is part of two triangles, and we get a consistent orientation for the two of them if one orders the vertices in the opposite order of the other. The "sum" of all these triangles is the surface, the space of interest. If we wanted to integrate over the surface of the sphere, and if we bust the integral into the sum of the integrals for each of the triangular pieces, we'd be looking at something that smells like a chain — complete with orientation.

A boundary is literally what its name implies. For the sphere, there is no boundary. This falls out of the calculations easily as well. Each triangle has three edges. Each edge is shared with another triangle, where it is reversed. Therefore each edge cancels in the sum. So algebraically, as well as intuitively, a sphere has no boundary, no "edge". A ball has a boundary; let's see it happen algebraically. Put a vertex at the center of the sphere, and convert each triangle to a tetrahedron. For the surface we had 2-simplexes; for the solid we have 3-simplexes. If we get the "orientation" right, each interior face is shared by two tetrahedra with opposite ordering. Now when we take the boundary of this solid, this chain of 3-simplexes, the interior faces cancel, but the exterior faces remain. Thus the boundary of the ball is a sphere (with orientation!), and the boundary of the sphere cancels to nothing.

OK, so we need chains to describe triangulations (or to use a fancy term, simplicial decompositions), and boundaries are just what our intuition tells us boundaries should be. Boundary of boundary is zero, now and always. But, a thing can have a zero boundary without that thing being a boundary itself. For example, suppose a chain of 1-simplexes forms a closed and consistently oriented loop. Each vertex is shared by two edges, and is the leading vertex of one edge and the trailing vertex of the other. Thus a loop is a "cycle", a chain with no boundary. Boundaries are always cycles, so they carry no information.

Let's look at a solid torus, busted into tetrahedra. When we compute its boundary, we get the (triangulated) surface, which in turn has no boundary. Boring; no information there. But look at 1-cycles, and things get more interesting. A 1-cycle on the surface that loops the short way around is the boundary of a disk; no information. A 1-cycle on the surface that loops the long way around (circling the hole in the donut) is not a boundary (of something that is part of the torus); it tells us something. This is what the H1 homology group is about. The definition is logical, natural, one might even say inevitable.

There is much more that could be said, but I hope this gives you a sense that the terms have an easily-understood intuitive meaning, closely related to their names.

If you have follow-up questions, please ask them here and I will reply when (and if) I can. --KSmrqT 07:15, 10 November 2007 (UTC)

A few things[edit]

Good afternoon (although I guess it's G'day at your time in Australia). I'd just like to say that I was pleased to read your reply on the 0.999... arguments page. It was the first civil and rational thing I'd read on there; I myself being guilty of writing things that were less that civil. I was going to ask you how your homology studies are coming along. I happened to come across this comment on a discussions page. I came here to see if I could help. I'm familiar with singular homology and cohomology, and thought I could help. In fact I'm trying to get to grips with Čech homology [1] at the moment and I'm finding it slow going. Wikipedia doesn't have an article on Čech homology, but does have one on Čech cohomology. I've just seen the comment above so I guess you're still working on these things. If there's anything I can do to help then just ask. If you'd like to discuss some things then it will help me with Čech homology too.  Δεκλαν Δαφισ   (talk)  16:36, 5 October 2008 (UTC)


  1. ^ Andrew H. Wallace (2007). Algebraic Topology: Homology & Cohomology. Dover. ISBN 0-486-46239-0. 

MH problem[edit]

The thread at talk:Monty Hall problem#Glkanter's objection has gotten a little out of control. You posted (in response to my question about whether you've read the whole thread):

I have, but I'm still confused. Is the question "Is there a difference between between the cases in which [(the decision is made before) amd (the decision is made after)]" or is the question "Is there a difference between the probability of winning [(before) and (after)]"? In the latter case I can see there might be differences but in the former case I can't see how "at what stage the decision is made" can possibly influence the outcome. Maelin (Talk | Contribs) 10:50, 8 February 2009 (UTC)

The difference is when the decision is made because it changes the population we're interested in. If the sequence is:

  1. Player picks a door
  2. Player decides whether to switch
  3. Host reveals the goat

we have to be talking about all players (or the subset of players who have picked a particular door), not a subset who have picked a door and have seen which door the host opens in response.

In the normal sequence:

  1. Player picks a door
  2. Host reveals the goat
  3. Player decides whether to switch

the "community of interest" is the subset of players who have picked a specific door and have seen the host open some door in response. For example, if there are 3000 players all of whom initially pick door #1, in the first case we're talking about all 3000. In the second case we need to be talking about only however many have seen the host open one (but not the other) of the remaining doors. In the problem as typically stated, we're interested in the subset who see the host open door 3. This subset includes all of the players who will win by switching because the car is behind door 2 (in which case the host must open door 3) and some fraction of the players who have picked door 1.

The sentence in the problem statement that says If both remaining doors have goats behind them, he chooses one randomly lets us say that we expect the host will open door 3 roughly half the time if the player initially picks door 1, so the total number of players we care about (the ones who see the host open door 3) is roughly the 500 who have picked the car plus the 1000 who have picked a goat (when the car is behind door 2). This makes the odds of winning by switching 1000/1500 (i.e. 2/3). The "random goat" host constraint makes the problem symmetric with respect to which door the host opens, i.e. the numbers are the same if the host opens door 2, and makes the conditional probability given either door the host opens the same as the unconditional probability (the probability across all players).

The reason this is an important distinction is because it doesn't have to be the case that the unconditional probability and conditional probabilities are the same. In particular, in the variant where instead of picking between two goat doors randomly the host prefers the lowest numbered door the numbers change. If we're figuring out the probability of winning if the host opens door 3 we have only the 1000 players who initially picked a goat (with these rules, for all 1000 who initially picked the car the host will open door 2). This makes the conditional probability of winning for the players who see the host open door 3 100%. In this variant the unconditional probability is still 2/3.

Reading your comment again - I suppose in the "decide before" case, we could be asking about the conditional probability for players who then go on to see the host open door 3. Is this what you mean? This would make it the same conditional probability question as the "decide after" case. -- Rick Block (talk) 17:56, 8 February 2009 (UTC)

Okay, I think I understand, let's see if I've got it right. We are noticing the difference in results because we have introduced a fault into the host's behaviour that can be exploited by a clever player. In this case, a 'clever' player is one who waits to decide his move until he sees which door the host opens. Assuming the player is clever, the player who waits has additional information (by watching the host) that he can use to improve his chances of winning. A stupid player, however, makes up his mind before going in and does not take advantage of the additional information given by the host's faulty behaviour. As such, a stupid player cannot improve his odds above the 2/3 result for the vanilla MH problem, but a clever player CAN improve his odds thanks to the extra information he derives from the host. Is that correct? Maelin (Talk | Contribs) 01:27, 9 February 2009 (UTC)
Sort of, but calling this clever/stupid is not quite right. It's just different. For example, if the host happens to open door 2 in the "lowest numbered door" variant the player's chance of winning is now 1/2 rather than 2/3. The point is things might change when the host opens a door, and in the usual way the problem is presented the host has already opened the door, so the analysis should be a conditional one (using all we know about how the host decides what door to open) rather than an unconditional one. The fully specific problem description currently in the article at Monty Hall problem#Problem forces the numeric answer for the conditional problem to be the same as the unconditional problem, mostly to avoid confusing people (although I think it is this very point that is confusing Glkanter). -- Rick Block (talk) 02:07, 9 February 2009 (UTC)

Little Minnesota[edit]

Sorry, but these sections in almost all of the HIMYM episode articles violate WP:TRIVIA, which states "A number of articles contain lists of isolated facts, which are often grouped into their own section". Nothing is sourced or notable. It is fine on IMDB, but unless the references are sourced and notable, they have no place in these articles. Rwiggum (Talk/Contrib) 05:10, 23 February 2009 (UTC)

Unexpected hanging paradox[edit]

The template you've added in 2006 is still in place, despite large changes and additions. It seems nobody was in the mood of being bold and removing it.

Perhaps you may be bothered to check yourself and either remove the template or leave criticism at the talk page.

--Pjacobi (talk) 12:44, 11 May 2009 (UTC)

Oh, thanks! The article looks much better now, I will remove the template immediately. Maelin (Talk | Contribs) 14:36, 11 May 2009 (UTC)

Steampunk List[edit]

Please do not add items to the steampunk list without also adding a citation.

The list has had in the past a serious problem with cruft and unrelated additions. To combat this, it's been pretty much agreed upon that any item added to the list without a citation should be eliminated on sight.

Even an mention on the item's own wikipedia entry was eventually deemed not good enough because people started going and adding the word "steampunk" into their favorite movie's article just so they could add it to the list.

(Exception to avoid being ridiculous : Items with "steampunk" in the title. )

I've fixed it, but in the future, if you're adding something, we'd appreciate it if you'd also cite it so we don't waste time reverting each other.

Thanks. APL (talk) 19:53, 6 September 2009 (UTC)

Meetup invitation: Melbourne 26[edit]

Hi there! You are cordially invited to a meetup next Sunday (6 January). Details and an attendee list are at Wikipedia:Meetup/Melbourne 26. Hope to see you there! John Vandenberg 07:42, 27 December 2012 (UTC)

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