Asia Information Retrieval Symposium (AIRS) 2009 was the ?fth AIRS conf- ence in the seriesestablished in 2004.The ?rst AIRS washeld in Beijing, China, the second in Jeju, Korea, the third in Singapore and the fourth in Harbin, China. The AIRS conferences trace their roots to the successful Information Retrieval with Asian Languages (IRAL) workshops, which started in 1996. The AIRS series aims to bring together international researchers and dev- opers to exchange new ideas and the latest results in information retrieval. The scope of the conference encompassed the theory and practice of all...