Thank you for your kind words. I'm glad you've found my post useful. And that's a good catch about node/r.
It looks like the two versions of node/r differ just in the case when (depth x!lf) = (depth x!rt) [and likewise for y], which it appears I had assumed would not be true; perhaps that was valid for insertions but not deletions. (I must admit deletions came as a bit of an afterthought, as evidenced by the typos in "aremove".) I'm pleased that the resolution is so simple.
Anyway, thanks to you, we now have AVL trees that are actually tested and proven to work.
