Okay, it's posted here!
* [Petri net programming (part 3)](http://johncarlosbaez.wordpress.com/2013/04/19/petri-net-programming-part-3/), Azimuth Blog.
Thanks a lot, David! I'll try to get some people on G+ interested in it, and I hope they have questions and comments, and I hope you can respond to them.
By the way, I made a couple of small edits at the last minute:
* In TeX the exponential function is `$\exp$`, not `$exp$`. This produces $\exp$, which is better than $e x p$. Same goes for all our favorite functions. (On the Wiki and Forum, we are lulled into a false sense of security by Jacques Distler's decision to make multi-letter strings come out roman rather than italic in math mode. So on the Wiki you'll have seen `$exp$` give $exp$, but that doesn't work most places, and I really wish this "feature" had been omitted.)
* It's best whenever possible to use HTML instead of Markdown on articles that are going to become blog posts, since Wordpress uses HTML.