  Query Understanding is a semantic search method that can classify tokens in a
customer's search query to entities such as Product, Brand, etc. This method
can overcome the limitations of bag-of-words methods but requires an ontology.
We show that current ontologies are not optimized for search and propose a
simplified ontology framework designed specifically for e-commerce search and
retrieval. We also present three methods for automatically extracting product
classes for the proposed ontology and compare their performance relative to
each other.
