Sprugnoli presents a systematic derivation of several properties of binary trees by using “leaf analysis,” that is, deriving simultaneous recurrence relations by inserting in any tree with N nodes a new node as a leaf in all the possible ways.

The paper is well written and clear. It is a good piece of theoretical work. The author solves the recurrence systems using a single technique by which both the average value and the variance relative to each property can be found.

The set of references is good. The paper is a good exposition of an interesting theoretical result. While the material is related to data structures, notably binary trees, the paper in its entirety will be of greatest interest to those with a good understanding of combinatorial mathematics.