Le Zhao - Thursday 2nd Oct 2008

We are going to have Le Zhao to give our first IR talk in this
semester. Reception will provided by Yahoo!. Here is the talk information:

Date: Thursday 2nd Oct 2008
Time: 2pm
Place: Wean Hall 7220

Speaker: Le Zhao
Title: A Generative Retrieval Model for Structured Documents

Abstract
Structured documents contain elements defined by the author(s) and annotations assigned by other people or processes. Structured documents pose challenges for probabilistic retrieval models when there are mismatches between the structured query and the actual structure in a relevant document or erroneous structure introduced by an annotator. This paper makes three contributions. First, a new generative retrieval model is proposed to deal with the mismatch problem. This new model extends the basic keyword language model by treating structure as hidden variable during the generation process. Second, variations of the model are compared. Third, term-level and structure-level smoothing strategies are studied. Evaluation was conducted with INEX XML retrieval and question-answering retrieval tasks. Experimental results indicate that the optimal structured retrieval model is task dependent, two-level Dirichlet smoothing significantly outperforms two-level Jelinek-Mercer smoothing, and with accurate structured queries, the proposed structured retrieval model outperforms keyword retrieval significantly, on both QA and INEX datasets.

Based on work accepted at CIKM'08.