Safety as understood in the conference theme can be separated into the more technical terms of safety, progress, and security: nothing bad happens, the right things do happen, and things happen under proper authorization. All three interact to make a system \safe " in the broader sense. This article introduces to the degree of safety in the technical sense that can be directly supported by programming languages and their type systems in particular. From a generalized de nition of type a brief journey through contemporary type systems is taken and illustrated using examples from di erent programming languages. Finally, current trends and some novel approaches are presented. 1

ion for expressing logical parallelism through the Mianjin language . Gardens Tasking Systems for Process Migration and Control Gardens support migration of tasks from one workstation to another workstation for adaptive parallel computing on networks of non-dedicated workstations. Migrated tasks can continue to perform valid I/O operations on files, which are associated with the network file system (NFS), where the underlying NFS is slow. However, if a Gardens task opens a file on a disk storage space physically associated with a particular workstation, it cannot access such files after migration to another workstation. This is the first issue the proposed research addresses by providing transparent access mechanism for accessing files under task migration. The second issue addressed by the proposed work is to develop adaptive parallel file system supporting parallel I/O under migration. The third issue addressed by the proposed research is a set of parallel I/O libraries and buildi...

Contents 1. Research Centre and the Proposed Research Alignment......................................................................2 1.1 Research Centre ...................................................................................................................................2 1.2 Centre Background................................................................................................................................2 1.3 Proposed Research Alignment with Gardens Project ...........................................................................2 2. Coursework to be undertaken .................................................................................................................2 3. Proposed Title ...........................................................................................................................................2 4. Objectives of the Program of Research, Motivations, and Investigation.............................