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An easy introduction for elementary basics is
The following provides more details.
See also the FAQ.
The Lab displays mathematical symbols using MathML. Displaying MathML requires support from your web browser. The browser with the best support for MathML is Firefox, especially if you install the STIX fonts. Firefox is a great browser in many other ways too, so if you aren’t using it, why not give it a try?
Recent versions of Opera also apparently support MathML. For InternetExplorer, one needs to install the MathPlayer plugin. Download is quick and easy and free, but installation may require Administrator privileges on your computer. Other browsers such as Safari and Chrome seemingly do not support MathML at present.
(Firefox - and clones - specific)
Here are some search plugins for firefox that will let you search the nLab from the firefox search bar.
It would be nice if these had different icons. To use one or more of these, drop them in the ‘searchplugins’ directory of your firefox profile.
(Firefox - and clones - specific)
One way to do this is to install this firefox extension or another one like it.
If your favorite editor is Emacs with AucTeX, you may find the following snippet useful to put in your .emacs file:
(add-to-list 'auto-mode-alist '("/\\(www.\\)?ncatlab.org" . latex-mode))
(add-to-list 'auto-mode-alist '("/golem.ph.utexas.edu" . latex-mode))
(defun nlab-latex-fixes ()
(when (or (string-match "/\\(www.\\)?ncatlab.org" buffer-file-name)
(string-match "/golem.ph.utexas.edu" buffer-file-name))
(longlines-mode t)
(set (make-local-variable 'TeX-open-quote) "\"")
(set (make-local-variable 'TeX-close-quote) "\"")))
(add-hook 'LaTeX-mode-hook 'nlab-latex-fixes)This will tell Emacs to automatically edit nLab pages (and nCafe comments as well, for good measure) in LaTeX mode, with long lines wrapped using soft returns, and ordinary double-quotes rather than LaTeX ones.
(Firefox - and clones - specific)
You may wish to customize the font scheme (both for math or text) on the nLab, as well as tweak things such as the small edit box for comments. Try the nLab Stylish theme theme if you are using Firefox. (Stylish is a plug-in for firefox enabling you to customize websites; it is available here). The nLab theme changes the fonts on the nLab to a serif-style, and makes the edit box much bigger for an overall more pleasant experience! Experienced users can also do this themselves by tweaking the CSS. You might also want to try a Firefox extension which allows you to edit the text box using your favourite text editor.
The inbuilt export features of the n-Lab have been switched off. However, it is still possible to get a local version of the n-Lab. This is a static version in that you cannot edit pages, but is complete and all the links correctly point to the pages on the local version.
One way to do this on a Unix-based system (Linux, MacOSX, BSD), is to use the wget command. The command is:
wget --output-document=- http://ncatlab.org/nlab/list \
| perl -lne '/<div id="allPages"/ and $print = 1;
/<div id="wantedPages"/ and exit;
/href="([^"]*)"/ and $print and print "http://ncatlab.org$1";' \
| wget -i - -kKEpNIf you are fortunate enough to be using the Z-shell then you can type it exactly as written. Other shells may complain at the line-breaks in the perl code (they should be alright with the backslashed line-breaks). If so, simply type it all as one line.
One huge advantage of this script over the inbuilt export is that if you run it from the same place each time, it will only download modified pages. That saves a lot of bandwidth and time.
The following is an explanation of how it works. The first step is to get a list of all the pages, we do this by downloading the All pages page and extracting a list of the pages (via a perl script). We feed this back into wget as a list of pages to get (using the -i option). For each downloaded page we ensure that we have the required extras to display it correctly (-p option), we convert the links so that they work correctly: links to downloaded files point to downloaded files, links to non-downloaded files point to non-downloaded files (-k option), we use time-stamping to only get new pages (-N), but because we’re doing a little post-processing we need to keep the original files for time-stamping to work correctly (-K). Files are also converted to html extension (-E) since no matter how they were generated, they are now boring html (well, okay, xhtml+mathml+svg) files.
If anyone can post instructions for other operating systems, or other programs (such as curl) then please do so.
Hit “edit page” to see how pages are coded. Use the Sandbox to warm up.
Creating a new page is done by
first creating a preliminary link (represented by a question mark) by entering double square brackets;
then clicking on the question mark and following the instructions.
Watch out: the name of a page is case sensitive, so make your link lowercase if it comes at the beginning of a sentence. ([[like this|Like this]].) We loosely agreed to try to follow that and some other naming conventions; see below.
However, this is less of an issue now that we have redirects.
When you edit a page, you can (and should) put your name (with normal capitalisation and spacing) in the box after ‘Submit as’. If you don't, then your contribution will be credited to the AnonymousCoward.
Once you edit a page for the first time, your name will appear at the bottom, grayed out with a question mark since there is no page with your name yet. You may take this as an invitation to create a user page and tell us about yourself. But if you don’t want to or don’t have the time right now, you can forget about this. If you just want to show up on category: people, then you make a page containing only ‘category: people’ (or someone else may do this for you).
To create your user page, simply click the question mark that appears next to your name at the bottom of the page after making a modification and add content to the edit box that appears. If you’d like to make a user page prior to modifying an existing page, you can do so by making some trivial modification to the Sandbox, which will put your name at the bottom of the page where you can click the question mark. (Or hack the URL.)
These are not set in stone, but we're following them for now. Most days, Toby Bartels goes around and corrects any violations (while reading the new material). But changing page titles results in unnecessary kruft (in category: redirect), so you should try to follow these if possible (or dispute them if not!).
Page titles should contain only ASCII characters.
[[omega-category]] instead of [[$\omega$-category]] or [[∞-category]].$\omega$-[[omega-category|category]]. Unfortunately, $\omega$-category does not work.[[∞-category]] is now redirected to ∞-category.Page titles should be singular nouns.
[[category]] instead of [[categories]], [[faithful functor]] instead of [[faithful]], and [[categorification]] instead of [[categorify]] or [[categorified]].[[category|categories]]. To produce ‘faithful endofunctor’, try [[faithful functor|faithful]] [[endofunctor]].[[category|categories]]. If you find yourself frequently typing [[internalization|internal to]], then you might consider adding a redirect to internalization (which we’ve done now) so that [[internal to]] is redirected to internal to.Page titles should be uncapitalised, except for word words that are always capitalised.
[[homotopy theory]] instead of [[Homotopy Theory]], but use [[Lie algebra]].[[homotopy theory|Homotopy theory]] is important!.Except as contradicted above, use standard American English spelling conventions.
[[internalization]] instead of [[internalisation]] and hyphens as shown in the ASCII-only requirement.[[internalization|internalisation]].Regardless of the above, pages named after specific categories should use the capitalised singular abbreviated form.
[[Set]] instead [[Sets]] and [[Cat]] instead of [[Category]].If you want to make a comment or question about a page without changing its main content, then edit the page and put your comment or question in a query block as shown in this example:
+-- {: .query}
How do I ask a question?
=--which produces
How do I ask a question?
Note that a query block should be less permanent than the rest of the page; once your comment is addressed or your question is answered, you can probably remove your query block.
If you want to ask a question of a specific person, then you can place a query block on their user page (which is just a page whose title is their name). You should be able to find all user pages here.
If your comment or question is more general than a specific page or person, then try the n-Forum. Previous discussions have been on the General Discussion page and on an entry at the n-Cafe. These previous discussions should not be added to but you may find your question answered there. Important answers are being migrated to this How To and the FAQ. As this is a Wiki, if you find an answer to your question and feel it should be added to one of those then do so.
If you want to make some text stand out (an important theorem, or slogan), you can do it using a standout box:
+-- {: .standout}
First quantization is a mystery, but second quantization is a functor.
=--which produces
First quantization is a mystery, but second quantization is a functor.
To fiddle with the CSS code, go to “Edit web” on the main page of your wiki, and then click on “Stylesheat tweaks”. Here you can add new CSS gismos like query boxes and standout boxes. These kind of gismos come from the mechanism of putting CSS classes into the Markdown syntax, in the same way that Jacques created the Theorem environments in Instiki. In other words, a query box is like a theorem environment: it’s a way in Markdown to create an HTML block with a specific id, which you can then style in the CSS. You can grab the CSS code for query boxes from the main nLab page. It requires a password to change the CSS, but to view it does not require one.
If you have some material at a page called foo that you want to include directly in pages called bar and baz, then type [[!include foo]] in bar and baz. For an example, see how contents is included at the tope of this page. Also see how contents itself has been formatted so that it will appear as a sidebar when included.
Besides such sidebars that appear in many pages, you can also use inclusion to put in something that contains a bunch of ugly code (such as raw SVG) without mucking up the rest of the page. That is, you put your messy code in bar/foo and then put [[!include bar/foo]] in bar. Note that this is for something that, logically, should appear within bar itself, which is why bar appears in the name of the included page.
Note that the included page goes directly in where it is called with no surrounding whitespace. This can mean that formatting rules are broken on the include. For example, if the included file starts and ends with a div tag and is included with no surrounding blank lines then this breaks the rules and will generate an error.
See redirects.
Since the mechanism for inserting links uses parentheses to delimit the link, it’s not obvious how to put parentheses actually in the link itself. Since Wikipedia uses them a fair bit, it’s worth knowing how to put them in. The trick is to use the URL codes rather than the actual characters. URL codes are generally used to send “unsafe” characters in URLs (safe characters are a-zA-Z0-9$-_.+!\*'(),). Although parentheses are actually “safe”, due to their special meaning for the markdown filter, to put them in URLs here they need to be treated as “unsafe”. URL codes have the syntax %hex where hex is the index of the character in the ASCII character set represented as a 2-digit hexadecimal. Wikipedia (among other places) has a table of the character set from which one can read off the required hexadecimal. In particular, we see that ( is %28 and ) is %29. Thus
[Monad (category theory)#Monads and adjunctions](http://en.wikipedia.org/wiki/Monad_%28category_theory%29#Monads_and_adjunctions)Insert the symbols
* tic
{:toc}(including the line break!) at the position where the table of contents is to appear. Its items will be the section headlines marked by
# top leven headline #
## second level headline ##
etc.Instead of “tic” (which is just a joke inspired by “toc” for “Table Of Contents”) here you can write anything you like: this line will not be displayed but is still required. A useful thing to type is for instance
* automatic table of contents goes here
{:toc}since this will indicate to everyone looking just at your source code what the command will accomplish.
It is also important that the section headings not contain anything that shouldn’t go in the table of contents. Whilst formatting is allowed, wiki-links are not (since then the entry in the table of contents would be double linked).
The itex syntax accepted by the nlab doesn’t understand the syntax of any diagram-drawing package akin to xypic or tikz. (Many of us would love to improve matters; see the forum, and chime in if you have any suggestions.) At present there are basically three ways to make diagrams: hack it together with arrays, include an image file, or include SVG.
Use arrays or matrices. For example,
$$
\begin{matrix}
(f/g)& \to & A \\
\downarrow&\underset{\alpha}{\swarr}&\, \downarrow f\\
B &\underset{g}{\to} & C
\end{matrix}
$$produces
In many cases, you want to tweak the alignments (say, of vertical arrows), using \mathrlap{} or \mathllap{}:
is produced by
$$
\begin{matrix}
B^{\mathrlap{A}} & \longrightarrow & 1^{\mathrlap{A}} \\
\mathllap{\scriptsize{\sigma^A}}\downarrow & & \downarrow\mathrlap{\scriptsize{t^\alpha}} \\
P(B)^{\mathrlap{A}} & \underset{\chi_\sigma^A}{\longrightarrow} & P(1)^{\mathrlap{A}}
\end{matrix}
$$Include an image file: This is the quick-and-dirty method. To create the image file, either use a program like textogif to create the image from a TeX file locally, or use a web service like codecogs. Then follow the instructions here for putting it on the lab.
Include SVG: This is arguably a “better” method, since unlike an image (and like MathML) SVG can be scaled with the text, and (in theory) edited by other users without recreating the entire diagram. There are various methods for producing SVG. You can use a vector graphics program that produces SVG output (anyone have a good one to suggest?). You can also just copy the SVG from another page and modify it by hand; some pages currently containing SVG diagrams are monoidal category, oriental and comma object. Once you have some SVG, you can modify it by hand to put in the itex math; use the SVG <foreignObject> tag with a $...$ inside it. You need to put markdown="1" on the <foreignObject> tag, or else on a <g> tag containing it.
Once you have the SVG, you can include it on a page as described here. Since raw SVG is a bit ugly, you may want to put the SVG on a “subpage” by itself (with a name like pagename > imagename) which is included from the main page (see above for the syntax to include other pages).
For general information and help with Instiki, see the Instiki wiki.
Here are some useful specifics: * Use basic Markdown syntax * Make tables, footnotes, etc * Add definitions and theorems * Add metadata to your markup * Type itex equations * Use wiki syntax * Embed SVG in equations * Upload files * Use keyboard shortcuts * Make slideshows
Revision on October 22, 2009 at 18:37:23 by Toby Bartels See the history of this page for a list of all contributions to it.