We have been working on a design for an authentication service for a distributed system. The design has three goals that we fed have not been met simultaneously by any previous design. First, the service must be able to grow to cover an arbitrarily large…
We examine the problem of explaining expert system recommendations derived from complex reasoning strategies. We focus on the difficulty of justifying advice generated by hypothesis-directed reasoning. In this context, we discuss research on the PATHFINDER system for the diagnosis of lymph node pathology. We present…
One of the most striking features of the H-mode, in contrast to the L-mode, is the existence of very steep pressure gradients in a narrow layer just inside the plasma boundary. In this paper, it is shown how the existence of H- and L-regimes, together…
This paper is an overview of the software environment (called AGORA) that is being developed at Carnegie-Mellon University to support the devlopment of connected, speaker independent, speech recognition systems. This includes the design, implemenentation, testing and fast (parallel) execution of speech recognition programs composed of…
We present a logical relationship between a small number of intuitive properties for measures of belief and the axioms of probability theory. The relationship was first demonstrated several decades ago but has remained obscure. We introduce the proof and discuss its relevance to research on…
Consider a database containing not only base relations but also stored derived relations (also called materialized or concrete views). When a base relation is updated, it may also be necessary to update some of the derived relations. This paper gives sufficient and necessary conditions for…
It is shown that there is a unique configuration of toroidal magnetic surfaces which has the property that it corresponds to more than one plasma equilibrium and that this is the configuration ofisodynamic equilibria. These equilibria include toroidal minimum-B equilibria and the distinction between these…
For some time I had been looking for a mutual exclusion algorithm that satisfied my complete list of desirable properties. I finally found one--the N!-bit algorithm described in this paper. The algorithm is wildly impractical, requiring N! bits of storage for N processors, but practicality…
Most computer scientists regard synchronization problems, such as the mutual exclusion problem, to be problems of mathematics. How can you use one class of mathematical objects, like atomic reads and writes, to implement some other mathematical object, like a mutual exclusion algorithm? I have always…
Soon after I arrived at SRC, I was approached by some people at WRL (Digital's Western Research Laboratory) who were building a multiprocessor computer. They wanted to avoid having to add synchronization instructions, so they wanted to know how efficiently mutual exclusion could be implemented…
This paper describes a file system for a programmer's workstation that has access both to a local disk and to remote file servers. The file system is designed to help programmers manage their local naming environments and share consistent versions of collections of software. It…
Maximum-likelihood estimates of the parameters of exponentially damped sinusoidal signals in noise can be found by using an iterative procedure based on Newton's method. The initial estimate is obtained by an improved linear-prediction method. The properties of the Newton estimates obtained from short data records…
