Remote access feels different from local access. The major issues are consistency (machines vary in GUIs, applications, and devices) and responsiveness (the user must wait for network and server delays), Protium attacks these by partitioning programs into local viewers that connect to remote services using application-specific protocols. Partitioning allows viewers to be customized to adapt to local features and limitations. Services are responsible for maintaining long-term state. Viewers manage the user interface and use state to reduce communication between viewer and service, reducing latency whenever possible. System infrastructure sits between the viewer and service, supporting replication, consistency, session management, and multiple simultaneous viewers. The prototype system includes an editor, a draw program, a PDF viewer, a map database, a music jukebox, and windowing system support. It runs on servers, workstations, PCs, and PDAs under Plan 9, Linux, and Windows; services and viewers have been written in C, Java, and Concurrent ML.

This note discusses user dissatisfaction with the need to uncomment data statements in Algorithm 528, comments on alternative approaches tried by the community, and proposes a solution that is both automatic and safe.

Distributed administration of network repositories demands a low-overhead procedure for cooperating repositories around the world to ensure they hold identical contents. Netlib has adopted some refinements on the widespread scheme of anonymous ftp and s-R. Checksum files and two small C programs give an easily maintained system that copes with communication breakdowns and subtle changes in repository contents. The packaging of these C programs inside a shell pipeline provides an explicit command stream that can readily be checked before execution. Protecting files, keeping logs, and so forth become effortless and reliable. The same tools, applied on a smaller scale, allow more people to participate in the editorial work of maintaining a high-quality repository, by eliminating the need for directly manipulating files at remote sites.

Software tools are traditionally connected using human-readable files, an approach that buys flexibility and understandability at some cost in performance relative to binary file formats. The possibility of using shared-memory functions to retain most of the existing style while leapfrogging the speed of reading binary files, at least in some environments and for some applications, is explored. Results of a benchmarking experiment confirm the benefits of this alternative.>

We study grasps by a robot hand with three spring-loaded fingers. In two dimensions, the hand can grasp any polygon stably. That is, the grip is at a local minimum of the potential energy function defined by the springs of the fingers, ignoring friction. Surprisingly, under some conditions an equilibrium grasp on a circle is unstable even with respect to translation. In three dimensions, the hand can grasp and lift any cylindrical surface with a polygonal cross-section. In contrast we show that a hand with finger angles fixed at 120°, as proposed by Hanafusa and Asada, generally can not achieve a two-dimensional stable grip in the absence of friction.

We study grasps by a robot hand in the absence of friction. In two dimensions, a hand with three spring-loaded fingers and five degrees of freedom can achieve an equilibrium grasp on any object described by a polygon. Furthermore, the grasp is stable, that is, at a local minimum of the potential energy function defined by the springs of the fingers. In three dimensions, the hand can grasp any cylinder. In contrast, if the degrees of freedom of the hand are restricted to correspond to a hand built by Hanafusa and Asada, stable grips on a polygon cannot in general be achieved.