Two approaches to weighting vertices in rooted trees of hierarchical classifiers that characterize subject domains of various information retrieval systems are presented. Weight characteristics are examined depending on the position of vertices in the rooted tree — namely, on the level, depth, number of directly subordinate vertices (the «sons» clan), and number of hierarchically subordinate leaf vertices. The specifics of vertex weighting in a rooted tree are illustrated based on: weighted summation of level‑based, depth‑based, clan‑based, and leaf‑based vertex weights; hierarchically additive summation of leaf weight characteristics.

Keywords: information retrieval systems, hierarchical subject classifiers, hierarchical categorizers, subject indexing, vertex weighting in a rooted tree, level‑based weight characteristic of a vertex, depth‑based weight characteristic of a vertex