14. One or more computer-readable storage media, storing instructions that enable a processor to perform actions comprising: automatically transforming data of a plurality of semi-structured pages, to determine one or more occurrence vectors and one or more position vectors; determining at least one root template based at least in part on the one or more occurrence vectors; determining at least one detail template based at least in part on the one or more position vectors, wherein determining the at least one detail template comprises: dividing document object model (DOM) trees of the plurality of semi-structured pages of the cluster into a plurality of blocks based at least in part on a plurality of tag path text items present in the root template; detecting one or more patterns in each block of the plurality of blocks to identify additional data fields; identifying an additional data field of the additional data fields to be one of a first type or a second type in a block of the plurality of blocks, the identifying enabling the block to be split into a plurality of new blocks, wherein the first type comprises a data field located after a tag path text item which occurs once in at least a predetermined number of semi-structured pages and the second type comprises a data field following an equivalence class that occurs one or more times and for which no other tag path is present; and repeating the detecting and the identifying for the plurality of new blocks; and extracting structured information from the at least one root template and the at least one detail template.
19. The one or more computer-readable storage media of claim 14 , the actions further comprising: receiving a query; identifying one or more keywords in the query that are associated with data fields of structured information in the knowledge base, the identifying enabling a classification of the query into one or more query intents; and retrieving the structured information from the knowledge base based at least in part on the query and the one or more query intents.