The n-Category Café

Yes. There is currently a discussion of that point in a query box How to get started.

That query box should eventually be removed (we want query boxes everywhere but not on that particular page, I think) and the paragraph right above it should be upgraded to make the point explicit that you just mentioned.

Here is a request to those of our readers, who feel new to all this:

over in that green box at How to get started Bruce Bartlett, Andrew Stacey and myself are discussing roughly how we need to phrase the previous paragraph such as to keep it brief (that’s what I am aiming for, anyway) while at the same time making it very clear that you are supposed to copy-and-paste the source code of a blog comment into the $n$Lab, not to try to copy and paste the output.

How clear or not clear is this?

I don’t know if Urs, John, or David can recover the original markdown+itex syntax of a comment, but we humble lusers don’t seem to have that ability (not that we should).

Why shouldn't we?

In fact, if someone (which is mostly only Jacques) signs their comment with PGP, then you can look at the source code (part of verifying the signature). It shouldn't be too hard to allow that with any comment.

The “how to get started” page refers to using the Markdown with itex to MathML filter by default. Is there an automatic way to set it as the default, without having to manually select it every time? Hopefully without installing some complicated firefox extension? I feel like this is a basic thing that I should know, but I’ve never figured it out. It seems intuitive to me that one’s text filter preference should be saved along with one’s name, email, and URL, but that doesn’t seem to happen.

Hi João!

This just reminds me that I am due to write an entry.

Okay, thansk. I was wondering if you would still find the time. That’s great. The sub-web of Lie $n$-algebraic entries is badly in need of somebody taking care of it.

A question: is it possible to directly incorporate previously written latex, when there are definitions like \def \g {\mathfrak{g}} appearing in the preamble?

You can use all plain standard LaTeX commands, but not predefined macros etc, unfortunately.

It’s a sad but true fact that macros don’t work on Instiki, the software on which the $n$Lab runs.

If you have a lot of material in LaTeX that you’d like to contribute, the quickest method might be to set up some emacs macros that’ll do things like change your macro

\g

to the original LaTeX

\mathfrak{g}

When I’m done writing my Prehistory of $n$-Categorical Physics, I will try to put it and also the Rosetta Stone paper on the $n$Lab. Then I will need to become an expert at dealing with material that was written using macros.

Of course I wish some supergenius would invent a wiki that would run full-fledged LaTeX, including the ability to run macros, handle embedded Postscript figures, etc. But, no such supergenius seems to be available.

Is there no clever way of disabling Recently Revised through the current troubles?

Well, PHPLaTeX is not really even at the alpha stage yet. I’ve only tested it on firefox 3.0.x on Linux (don’t have a mac anymore, sob). Please send me the error message (via email) and I’ll take a look.

I know what you mean about full LaTeX to XHTML+MathML conversion and this isn’t an attempt to do it. It was originally an attempt to convert xymatrix figures to SVGs for putting on the n-lab. The main issue was getting the SVGs to look right (which is a pain due to the lack of coordination between the MathML and SVG parts). However, in the process of doing so I ended up writing a TeX processor in PHP (it’s not a proper TeX processor, rather an emulator).

I use PHP because that’s all I have available on my local system. I also have an earlier perl version for offline use (same principle, but not nearly so advanced).

I’d not heard of GELLMU before, thanks for the link. I do know about tex4ht, but what got me started was the fact that its tikz->SVG conversion is horrendous and I figured that tikz syntax is so close to SVG already that there must be a better way (TM). Plus the tex4ht implementation just seemed wrong!
(Why I actually started with xymatrix rather than tikz is boring.)

What doesn’t excite me about GELLMU is that it’s yet another LaTeX variant. I would prefer something that could understand a LaTeX document, ignore the stuff that is irrelevant to web presentation, and present the rest. I’m fed up having to learn new variants of stuff just to do my job (I learnt perl, now I have to learn PHP, and seems like I have to learn ruby now). Also, while learning new syntax is great for new projects then it’s useless for old ones, and it’s often those old ones where conversion is most needed.

Anyway, enough of the rant. I realise that I haven’t answered your original question! PHPLaTeX is a program written in PHP than can convert a basic subset of LaTeX input into XHTML+MathML+SVG. It’s big selling point is that it works by token expansion rather than pattern matching (okay, figuring out what a token is is currently implemented by pattern matching but I’ve got plans for catcodes). That means that macro expansion works as it ought to. At the moment, I haven’t finished writing the default command set so it’s not really suitable for full use yet (there’s also one or two routines that I need to work on). But Toby’s been trying it out a little (comments over on the n-forum). Any offers of help or encouragement will be gratefully received.

There is (you can check Google on this) only one Jacques Distler, who has rather finite resources.

Please remember that itex is not a fixed subset of LaTeX. It is whatever subset we (the users and implementers) want it to be.

The source code is in a BZR repository. If you, or anyone else, has a good idea for extending the syntax, do a

 bzr branch http://golem.ph.utexas.edu/~distler/code/itexToMML

and start hacking away. Send me an email when you have something.

The point was to have something that was

1. lightning fast
2. easily incorporated in a variety of content-management systems.

itex2MML is a Unix commandline stream filter, or a library for Ruby. (It’s easy, using SWIG, to turn it into a library for other languages, e.g. Perl. It’s just laziness that I haven’t done that – it’s almost as easy to do a system call, and use the stream filter.)

Several years ago when I was using LyX, I tested a few LaTeX to HTML converters and Tex4ht was the best and seldom required tweaking to obtain good output.

http://pear.math.pitt.edu/mathzilla/
The Problem: Putting math on the web is hard.
The Solutions: MathML Mozilla Tex4ht Itex2mml.

http://pear.math.pitt.edu/mathzilla/discussion.html
“Note also that a convenient way to prepare a html+itex document
(provided you have easy Web access) is to prepare the file in your
favorite editor, or html authoring tool (Composer, Word (hohum)…),
have the itex2mml file conversion page open in Mozilla, and carry
out a `edit document, save, press file upload button on the form,
view mathml page … and repeat’ sequence. Not exactly WYSIWYG …
but quite useful.”

http://pear.math.pitt.edu/mathzilla/itex2mmlFrag.html
A demonstration page is available. There you can enter a simple HTML
page with embedded itex, and have the page transformed into MathML.
[SH: There is a ready to go test page.]
——————————–

So this would require Firefox and maybe an itex editor such as AbiWord which are cross-platform. Somebody mentioned that it is a good idea to create and save the content of posts before posting to the web anyway, as they sometimes get eaten. An idea…