# A Calculus of Mobile Ambients

A.D. Gordon (University of Cambridge) LFCS Theory Seminar Room 2511, JCMB, King's Buildings 3pm, Monday 27th October 1997

If the net is the computer, what is the formalism? As a step towards an answer, we introduce a new abstraction, the ambient. An ambient is a named boundary enclosing a group of local processes and a group of smaller, nested ambients. We present a nominal process calculus of ambients, in which computation is based on primitives for ambient mobility and local communication within an ambient. The calculus is nominal in the sense that like the $\pi$-calculus, it includes a set of names and dynamic name generation. We can derive a variety of synchronisation and communication mechanisms and encode traditional computational models such as Turing machines, the $\lambda$-calculus and the $\pi$-calculus. More to the point, we show that ambients model a variety of net-centric concepts: named machines on a network, packets moving from machine to machine, mobile devices, mobile agents, encrypted packets and firewalls.

Joint work with L. Cardelli