Our friend Neil Trudinger has just turned 70 and it is a cause for celebration. Neil has been a friend, teacher, and/or mentor to many of us. Previous, this and the next issues are Special Issues in the Bulletin of Institute of Mathematics, Academia Sinica (N.S.) to mark this happy occasion.

There are several reasons for doing this. One is to highlight the global impact of Neil's research, as well as his educational efforts, and his highly cited book with David Gilbarg. Neil has had very substantial interactions with Eastern Asian mathematicians and he has been an inspiring presence in Taiwan over the years. For instance, Neil has supervised postdocs from Taiwan since the 80's. He was instrumental in initiating the Australia-Taiwan joint meetings in the 90's. Neil's enthusiasm in this matter then led to the series of Trilateral Australia-Italy-Taiwan Meetings. The Trilateral Meetings have been extremely successful, with the most recent one (Dec. 2012) held at the University of Wollongong.

Academia Sinica has been fortunate to host Neil over the years, and to have an opportunity to play a role in this celebration. We are happy to note that in doing this we have the blessings of Neil.

Sun-Yung Alice Chang, Department of Mathematics, Princeton University, U. S. A.

Nicola Fusco, Dipartimento di Matematica “R. Caccioppoli",, Universita di Napoli "Federico II", Italy

Tai-Ping Liu, Institute of Mathematics, Academia Sinica, Taiwan, and Department of Mathematics, Stanford University, U.S.A. .

Alan McIntosh, Centre for Mathematics and its Applications, Mathematical Sciences Institute, Australian National University, Australia