I need to calculate the edit distance between trees for a personal project of mine. This paper describes an algorithm, but I can't make heads or tails out of it. Are you aware of any resources that describe an applicable algorithm in a more approachable way? Pseudocode or code would be helpful, too.

解决方案

Here's some java source code (gzipped tarball at the bottom) for a Tree Edit Distance algorithm that might be useful to you.

The page includes references and some slides that go through the "Zhang and Shasha" algorithm step-by-step and other useful links to get you up to speed.

Edit: While this answer was accepted because it pointed to the Zhang-Shasha algorithm, the code in the link has bugs. Steve Johnson and tim.tadh have provided working Python code. See Steve Johnson's comment for more details.