Microblog Search Task at CLEF 2017: Query Generation using IR and LDA Topic Modeling Combination

The microblogs search task at CLEF 2017 consists of developing a system to search the most relevant microblogs for cultural query in a collection about festivals in all languages. Our general approach to get this objective is the following: we propose to generate from the initial tweet queries, provided for the task, extended queries able to get an answer-rich set of microblogs. This is achieved using a thematic representation of tweet query extracted from microblog corpus. We investigate in this paper a novel method to improve topics learned from Twitter content without modifying the basic machinery of LDA. This latter is based on Information Retrieval (IR) process to generate a query-specific set of similar tweets. The result then represent the input of a basic LDA topic modeling process. Finally, the output thematic cluster serves as our source of expansion for the initial queries. keywords: CLEF, Microblogs Search, LDA, Information Retrieval, Aggregation