# Help:FAQ

## "Why is this site so rubbish?"

... and other burning questions ...

Should your question not appear among the below, then feel free to put it on Help:Questions. We will try and answer within a reasonable amount of time.

## General questions

### What's the point of the Mathematicians page?

"The name of this wiki is ProofWiki. Thus I wonder if it is really necessary for this wiki to take on a huge historical task? Does it have a realistic chance to do a good job? At this moment the lists are far from complete, but it is hard to expect good results. Others are doing it already. Perhaps any historian can support other, more history oriented projects. It'll be hard to outdo them anyway."

A good question to which the only answer is "because I like it." If you really want the mathematicians page to be removed because it doesn't suit your idea of what this site ought to be, or that you want me to stop wasting my time on it and concentrate on what you think I ought to be working on (please provide a work schedule that you wish me to adhere to), you'll have to pry it from my cold dead hands. --prime mover (talk) 06:51, 20 December 2012 (UTC)

### I don't like the notation

"On such-and-such a page the notation is thus-and-so - I didn't like it, so I changed it to the notation I grew up with as a little boy back in the 1940's. It was good enough for Elijah, so it should be amply appropriate for you. But then - some rotten so-and-so changed it back!"

The world turns, life evolves, continents crumble to dust, and mathematicians occasionally devise notation which is considered an improvement over that which was originally invented.
It will forever be the case that there is more than one style of notation to illustrate a concept. The people who are familiar with notation A are going to complain if we use notation B, and those who grew up with notation B are going to be upset with our decision to use notation A. You can't please everyone.
Hence we choose a particular style, and we insist that all pages adhere to that particular style. This causes controversy, as followers of a particular symbol which has been turned down in favour of another, usually more modern, one which (in general) is less prone to ambiguity are going to be more or less offended.
So, if you don't like the particular notation that you see on a page, we are afraid that you are going to remain disappointed. If you have cogent reasons, and can articulate them well and in a polite manner, you may be listened to - but somebody will then need to be tasked with amending every single instance of the existing notation with your preferred. Such a task is tedious and time-consuming, and the maintenance team are in general antipathetic to such an eventuality. --prime mover (talk) 20:11, 30 December 2012 (UTC)

### Where is the proof?!

"I just visited Fundamental Theorem of Calculus (insert your favourite page) expecting to see a proof of this important result. However, despite the theorem being split up into two parts, I didn't find a proof for either of them."

As you can see, each of the two parts has a section heading in blue - it is a link. These links take you to an appropriate sub-page of the main result (e.g. Fundamental Theorem of Calculus/First Part).
The proof(s) of this part of the whole theorem are gathered on this subpage. Similarly, when multiple proofs are present, the headings "Proof N" often are also links, to the sub-page containing only that particular proof.
In this way, every proof (and definition) can be unambiguously referenced internally. This is important, for example, when establishing certain definitions are equivalent - we wouldn't want the proof of that to depend on its result. Thus, there is seen to be a need to be able to refer to a particular proof of a theorem. --Lord_Farin (talk) 12:25, 26 January 2013 (UTC)

### You undid my corrections

"I read such-and-such a proof and didn't like it much. I had a better one, so I removed the existing rubbish proof and put my better one in place. I went back next day to admire my work but found it had gone, and the old proof was back in place."

Whether or not you like a particular proof or not is of zero relevance. The fact is: it's a proof, and (at least believed by its author) it's valid. What we do on this site is allow multiple proofs for any given theorem. So, rather than replace the existing proof with your own proof, add your new proof as an additional proof to the one that is already up there.
There are quite a few pages up now which do have more than one proof. An excellent example of this is found at Real Numbers are Uncountable. What we do is put each separate proof into its own subpage which is then transcluded into the main page.
Basically, deleting stuff is rude. If you have objections about something on a particular page, then feel free to raise it as a topic on the associated talk page. It is possible the person posting it up may just have made a mistake. --prime mover (talk) 07:46, 20 December 2012 (UTC)

### Why do we need \left and \right with every pair of parentheses?

"Do we really need to put \left({ ... }\right) for every parenthesis, even things like $\sin(2x)$ and $(2n)!$? Out of curiosity, what difference does the extra curly inside \left(...\right) make? It seems to display the same."

The curly braces are grouping indications for $\TeX$; they serve to ensure that every \left is paired with the intended \right. Especially when using an external editor (e.g. via the Firefox plug-in It's all text) that highlights matching braces, such can greatly simplify the frustrating search for an occasional omitted or excess brace.
We enforce it to avoid problems with copy-pasting and subsequent editing of stuff inside parentheses. In this way, the parentheses will always size appropriate to their content, even if that content vertically grows or shrinks due to changes.
Equation references like $(1)$ and $(3′)$ are excepted from this admittedly strict style rule. --Lord_Farin (talk) 17:57, 13 December 2012 (UTC)

### Why a sentence on each line?

"I wrote a perfectly good dissertation, but then someone has come along and broken it up into simple kindergarten-level "the cat sat on the mat" style sentences, one on each line. This makes it look like a baby's first reader."

It makes it easier to follow a proof.
This is one of the more rigidly-enforced stylistic practices. Information is assimilated more easily if the flow of the argument is broken up into well-defined steps. In text books this practice is rarely seen, because that would increase the physical size of the book and the amount of paper it is printed on, hence the cost. This is why logical arguments in printed texts can be hard to follow.
On a website, there is no need to save space in this way. Therefore, we don't. We spread out the argument so it is as clear as possible.
(Little feedback has been received from the outside as to whether this approach has made the learning of mathematics in general easier as a result, but it may be worth setting up as a research project for anyone with a postgraduate degree to complete and a complete lack of inspiration on what to base the dissertation.) --prime mover (talk) 10:51, 21 December 2012 (UTC)

### Why the extra blank line?

"I did an edit on a section of one of the pages, then after I'd done so, someone else came in and edited the page just to add an extra blank line at the end of the section. Isn't that a bit pointlessly silly?"

The house style is such that the sections on the pages are spread out more than usual. This is a deliberate design decision: research has shown that information is taken from a webpage with greater ease when it is spread out more widely than it is on printed material. I have no intention of searching for documentary info on the web to back this up - it's just something I learned when I had an involvement in professional web design.
To that end, two blank lines are inserted in every page (with a few specialised exceptions where breaking the rule improves the presentation) at the end of every section before the next (sub)header. This needs to be done deliberately by hand.
Unfortunately MediaWiki software, when you edit an individual section, not the full page, removes any extra blank lines at the end of that section, making it necessary to go back and edit that whole page again to add the line it removed.
As a consequence, editing an individual section of a page is discouraged. It should not matter too much, because the policy of this site is to keep pages small. There are few pages over ten thousand characters, and many of those have been flagged as candidates for refactoring anyway. --prime mover (talk) 10:51, 21 December 2012 (UTC)

### Why bother to keep all those useless redirects?

"The name of such-and-such page has been changed from something that wasn't very meaningful to something that makes a lot more sense. But you're keeping the not-so-meaningful redirect. Why not just delete it and tidy up the site?"

Before a page is deleted, you need to make sure all the pages which link to it have their links changed to point to the new page. Otherwise you break the links. An easy way to do this is to select the link "What links here" in the Toolbox section in the menu bar down the left. Only when every page linking to this old unwanted redirect page have been so amended, and only then, is it okay to delete the page.
BUT: Even then, there may be external websites which may (however misguidedly) have a link to that page themselves. If this is the case, then their link to $\mathsf{Pr} \infty \mathsf{fWiki}$ will be gone. And that is a Bad Thing.
If the page being renamed is new, however, e.g. you just wrote it then noticed a spello in the title, then (after the renaming) it is usual for that particular redirect to be deleted, as there has been little opportunity for the page to have been noticed by the outside world and linked to. --prime mover (talk) 12:29, 21 December 2012 (UTC)

### What do you mean "sign your post"?

"I told you something interesting on one of the talk pages, but all I got was the terse response: "Please sign your post." What the factorial is that supposed to mean?!?!?"

The talk pages are where discussion of matters arising from the entry to which it is attached. Questions are raised concerning the meaning of that page, or why the notation was chosen as it was, or merely just to tell the person writing it that it's a load of rubbish and not worth the paper it's printed on.
As these pages are for discussion, it is useful to have a record of who said what, and when they said it, and to be able to follow the conversation.
So, whenever you enter a post on a talk page (not one of the main pages: definition or proof), you are required to sign your post. This is done by pressing the button at the top of the edit pane which contains a logo that looks like a squiggle. It should be the rightmost icon but one. What this will do is enter two hyphens followed by four tildes: }}. When you save that page, it will replace the four tildes with your user "signature" and the date at which it was posted, like you see at the end of this paragraph. Please do what you can to honour this request. --prime mover (talk) 17:38, 27 December 2012 (UTC)

### Why do you make such a fuss over the links in the "Sources" section?

"I moved one of the pages somewhere else and gave it a different name, then cleared out the original page and filled it with something else, then (etc. etc.) - and then you complained about me not having sorted out the citations? What's the point of that?"

In the "Sources" section, there is an attempt made for some of the sources to provide a path through the site which parallels the reading experience of that source. This flow is accomplished by means of "previous" and "next" links, which impose a strictly linear ordering of a subset of the site which corresponds to the path through those works.
If you change the name of these links, or copy a page complete with that link, this flow will be compromised, and it may no longer be possible to perform that reading experience.
If you change the pages such so that flow may have become compromised, then at the very least put an invocation of the SourceReview template into the "Sources" section of the page to indicate such. --prime mover (talk) 09:04, 12 January 2013 (UTC)

## Technical Questions

### Problem with Eqn template

"I've added a proof sequence using the eqn template, and despite my best efforts the parser barfs on it. It makes a horrendous mess that I can't work out how to clear up."

What's probably happened is that you have included instances of {{ or }} or | in your $\LaTeX$.
The MediaWiki template parser takes precedence over the MathJax one, and views {{ and }} as the beginning and end of the invocation of eqn, thus breaking the $\LaTeX$ in two. Similarly, it interprets | as the MediaWiki instruction to interpret what follows as a parameter value.
In order to get round this, you need to:
1. Put a conventional space between all instances of {{ and }} to make them { { and } }
2. Replace all instances of:
1. | with \vert
2. || and \| with \Vert, which renders as $\Vert$.
--prime mover (talk) 08:58, 8 March 2013 (UTC)

### Can't get a maintenance template to register my parameter

"I am trying to (for example) get the "explain" template to show:

{{explain|Why does $a = b$?}}

... but when it appears on the page, the "Why does $a = b$?" bit does not show."

This is because the MediaWiki template parser takes precedence over the MathJax one, and interprets your $=$ sign as being part of a parameter invocation. That is, it thinks that Why does $a is the name of the parameter being passed to the explain template and that b$? is its value.
In order to get round this, the = template was developed, which allows you to put the $=$ sign into an invocation of the template, like so:
{{explain|Why does $a {{=}} b$?}}
This should fix it.
--prime mover (talk) 08:58, 8 March 2013 (UTC)