1. A computer-implemented method comprising: accessing listing titles of one or more item listings on a marketplace website, the item listings being associated with a particular product category in a product category structure of the marketplace website; converting words in each of the listing titles to semantic tokens in a token symbol space, based on a tokenization process; performing n-gram modeling on the tokens corresponding to each of the listing titles of the item listings in the particular product category; and identifying, by a machine having a memory and at least one processor, one or more dominant n-gram models associated with the listing titles of the item listings in the particular product category, each dominant n-gram model identifying a sequence of one or more semantic tokens that appear in a statistically significant portion of the listing titles of the item listings in the particular product category.