ed abstract data types: Building blocks for collaborative applications Hyun-Gul Roha,∗ , Myeongjae Jeonb , Jin-Soo Kimc , Joonwon Leec a Department of Computer Science, KAIST, Daejeon, Republic of Korea b Department of Computer Science, Rice University, Houston, TX, United States c School of Information and Communication Engineering, Sungkyunkwan University (SKKU), Suwon, Republic of Korea a r t i c l e i n f o Article history: Received 23 July 2009 Received in revised form 11 October 2010 Accepted 4 December 2010 Available online 15 December 2010