3. The method of claim 1 , further comprising: receiving a user specification of an item listing title in connection with a user request to post an item listing on the marketplace website; matching the item listing title with the dominant n-gram model associated with the particular product category; and associating the item listing title with the particular product category.
4. The method of claim 3 , wherein the item listing title further includes a seller specification of a second product category distinct from the particular product category, and wherein the method further comprises notifying the seller that the item listing title is associated with the particular product category and is not associated with the second product category.