Change Doctype Based on Taxonomy

The default doctype for Drupal is XHMTL strict. The problem is, I'd like to use MathML as I am an engineering major and will have lots of formulas. That's simple, just change the default doctype for all pages to XHTML and MathML, like they show here.

The only problem is that a MathML page won't load in IE, the biggest browser, due to the doctype. If I get the MathML plugin for IE, it will load fine. If I open it with Mozilla, I'm fine. The simple solution would be to make Drupal spit out the XHTML with MathML doctype, but than every IE used would be blocked from my website.

Is there a way to change the doctype based on taxonomy, or an option when creating it, so the pages I have with forumlas will have the XHTML and MathML doctype, while every other page will have the plain XHTML Strict doctype? If I do it this way, IE users can browse the rest of my site, including a warning saying they need the MathML plugin if they want to see the pages with formuals.

I've also started a similar thread at Site Point Forums.