### 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)
UPDATE: This has now been more or less superseded by the new custom $\LaTeX$ commands which have recently been added. Please consult Symbols:LaTeX Commands/ProofWiki Specific for an idea of the sort of thing we are moving towards, for example: $\map f x$ is now generated using \map f x, and $\tuple {a, b, c}$ by \tuple {a, b, c}, and so on.

### 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 total lack of inspiration as to what to base the dissertation on.) --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 has 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 (for example, 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)
More recently we have taken to deleting the redirects, as soon as the pages linking to them have been appropriately redirected. So this FAQ is now of limited relevance.

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

"I entered a comment on one of the talk pages, and I was told: "Please sign your post." What does that mean?"

The talk pages are where discussion is held of matters arising from the entry to which it is attached.
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 third icon from the left, and if you hover over it, it will say "Signature and timestamp". 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. --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)
Also note that if you copypaste a page with such a citation into a new page, then unless you can confirm that the new page corresponds to material in the source work cited, then it is important to remove that citation. If the new page does correspond to material in the source work, then you are encouraged either to amend the links that define the source flow (remember to do that on the pages before and after the page in question), or to invoke the {{SourceReview}} template to alert the maintenance team that there is work to do. --prime mover (talk) 09:15, 26 November 2015 (UTC)

### How can I learn how to refactor if you don't allow me to refactor?

As a new contributor looking for something to work on, it can be discouraging to see that the majority of undergraduate mathematics has already been conquered. As a result, it is tempting to plunge into the considerable task of tidying up what already exists.
One of these tasks is "refactoring". This is a blanket term which encompasses the ongoing task to split existing pages with many subsections into a series of smaller pages which are then transcluded into the main page from which the subpages are extracted.
While on the surface this looks like a straightforward task, there is more to it than just extracting a section, putting it into a new page and then transcluding that subpage in. For example:
1. The new page needs to be standalone. Thus, if a page with "Proof 1" and "Proof 2" is being refactored, it is not sufficient just to extract those two proofs – you also need to extract the statement of the theorem itself and place it at the top of the page. The proof itself is then braced within "onlyinclude" tags so as to ensure that only the proof is transcluded into the master page.
2. At the bottom of many pages are citations of source references. (See above.) These need to be attended to. While it is easy to extract the sections and blindly copy these link sections into the new page, this compromises the linear flow of those works.
Because of this, it is considered that refactoring is a task best left to experienced editors. By "experienced", we specifically mean "experienced in $\mathsf{Pr} \infty \mathsf{fWiki}$". While it is appreciated that many contributors come to $\mathsf{Pr} \infty \mathsf{fWiki}$ from other wiki sites (often Wikipedia), the philosophy of $\mathsf{Pr} \infty \mathsf{fWiki}$ differs from that site significantly. To put it bluntly: anyone can post up mathematics on a website – it's easy. The more challenging aspects are to achieve a consistent style and to ensure a high level of rigor in the context of cross-linking.
The recommended technique for learning how $\mathsf{Pr} \infty \mathsf{fWiki}$ is structured is to spend some time and effort in exploring it, to see how pages are structured and to get a feel for how code is styled, in particular with reference to the house style. One will also take note of what amendments have been made to pages one has built oneself (with particular reference to the maintenance tags which may have also been added to such pages).
It should be accepted that in the early days of your involvement, you may find a multitude of amendments made to pages you have added. This is understandable, and will result in you adjusting your style so as to match the house standard. As contributors are by definition mathematicians, or at least mathematically literate and motivated, it is taken for granted that they have the ability to learn well, and to teach themselves by example.[1]
If it is apparent that a particular user has not yet taken the time either to learn the house style or to philosophically accept it, then that user is respectfully requested not to embark on refactoring tasks. --prime mover (talk) 10:11, 7 July 2013 (UTC)

## References

1. Once, at a formal evening attended by half a dozen logicians and mathematicians, one of the latter ventured the opinion that to become a good mathematician you should not have good teachers, as they prevented you from learning by yourself. He then added, courteously, "I was lucky. I had only one great teacher — Dr. Kasner here." Kasner looked up; his eyes twinkled; he said, mildly, "I had none."
From the introduction to The Mathematical Magpie, edited by Clifton Fadiman.