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October 31, 2007
Two Tech Topics
The STIX Fonts
After five years of blogging about the imminent release of the STIX fonts, they have finally been released in beta. I immediately rushed to install them. They are a huge improvement over Code2000/Code2001, which were previously required to complete the glyph coverage needed for rendering Math hereabouts.
The STIX fonts are not quite ready to replace the Mathematica/Computer Modern fonts for stretchy characters (parentheses, integral signs, etc). That will require internal changes to the Mozilla-based browsers. That, in turn, will require getting MathML working again in Mozilla Trunk. Since it’s been broken for over a year, don’t hold your breath.
arXiv API
A couple of years ago, the arXivs sprouted a Trackback interface. Now, they’ve developed an API to their search facility. Submit a query (via GET or POST), and receive the result as an Atom-formatted response.
This ties in rather nicely with one of my ambitions for Instiki: to add some bibliographic features. My plan was rather simple: store bibliographic entries in bibtex format (as retrieved from SPIRES or MathSciNet), and allow users to [cite:a_key] on their wiki pages. On the web, these would produce properly-formatted citations at the bottom of the wiki page. In the LaTeX export, it would produce \cite{a_key}, which would work with a bibtex file produced from the bibliographic database.
In such an environment, having arXiv search facilities integrated into the Instiki authoring environment would be a very nice addition1. And this is clearly the early days of the arXiv API. I’m pretty sure that more cool things are yet to come.
1 If you only care about citing the arXiv version of the paper, the <atom:entry> in the response provides all of the relevant bibliographic information. It’s only when you want to cite the published version, that the <arxiv:journal_ref> element needs some help. If the entry contains a <atom:link title="doi" rel="related"> DOI reference, that can sometimes be resolved (eventually) to a Bibtex entry for the published paper, but there are no guarantees.
October 28, 2007
Sanitizing SVG
For, perhaps obvious, reasons, I’ve been thinking again about sanitizing SVG. My most recent changes to the HTML5lib Sanitizer was to ensure that in constructions like
<rect width='0' height='0' fill='url(...)'/>
the referenced URL is a same-document reference, rather than one that pulls in an external resource from Lord-Knows-Where.
The white-list of elements and attributes in the HTML5lib Sanitizer is the union of a list for MathML that I came up with, and a list for SVG from Sam Ruby. I didn’t really put much thought into Sam’s list. But, once one starts thinking about things, one does start to wonder.
Is
<image xlink:href='http://bad.com/evil.svg'/>
really safe1?
Update:
Of course it’s not safe, as my little example for Anne (viewable only in Opera 9.5beta, but the same problem exists, mutatis mutandis, for<svg:image>) demonstrates. I’ve updated Instiki and the HTML5lib Sanitizer, accordingly.SVG is a gargantuan Specification. Even thinking about the security implications of Sam’s limited subset makes my head hurt.
1 On similar grounds, while I consider the standard <img src='http://bad.com/ugly.jpg'/> element fairly safe, I have to wonder at the wisdom of the decision in Opera 9.5beta to allow SVG in (X)HTML <img> elements.
October 22, 2007
SVG in MathML in …
As I’ve mentioned before, there is an effort afoot to enable the inclusion of MathML and SVG (and maybe other) markup in HTML5. But that’s a long way off (if it happens at all). What I really want to talk about, today, is an issue that affects us in the here and now: mixing MathML and SVG markup.
October 19, 2007
5 Years
Something else happened this past week: this blog turned 5.
While I cringe, a bit, looking back at my early posts, I’m kinda gratified that I’ve managed to keep this gig going as long as I have. I’ve certainly learned a lot: about Physics, about markup and — I like to think — about what makes a useful blog post.
Back then, Physics/Math blogs were not exactly thick on the ground. In fact, the genre pretty much didn’t exist. Today, the blogroll at Planet Musings is satisfyingly long.
And yet … I’m a little dissatisfied. Many of the meatiest, most exciting, entries on that list are actually in Mathematics: our own n-Category Café, Terrence Tao’s blog, the Secret Blogging Seminar …
That make me a little jealous. Damnit! We high energy theorists were here first! I think it’s time to try to reanimate the String Coffee Table. Any volunteers?
On a completely unrelated note, I learn, via Sam Ruby, that Liferea, the feed aggregator for the Gnome desktop, supports MathML, SVG and the Atom Threading Extension. That is extraordinarily cool.
October 18, 2007
Maloney on 2+1
We had Alex Maloney visiting us this week, and he gave a lovely talk about his forthcoming paper with Edward Witten on 2+1 gravity with negative cosmological constant.
You’ll recall that Witten’s proposal is that the dual CFT has a partition function of the form
where the central charge , with the radius of AdS3. is the partition function of the famous Monster Module. For higher , the first primary state above the ground state () has . One can systematically write down the