[tb99]

Hi, I wrote this post. The retrieval stage amounts to storing the top 50 categories in the inverted index and searching for the top 10 from the query. The harder part is the ranking. There are approaches to the ranking that are more akin to the techniques you'd use for text document search -- think of the classifier scores as TF-IDF values, treat query-to-category matching as something like synonyms -- but to my mind they're more complicated than our approach, not less. We did experiment a bit with some of these ideas, but the results were worse.