The mathematical description of three-dimensional surfaces usually falls in one of two classifications; parametric and algebraic. The algebraic form is defined as all points which satisfy some equation F(x,y,z)=0. This form is ideally suited for image space shaded picture drawing, the pixel coordinates are substituted…
Linkers, although a well-established component of language translation, are typically machine-dependent, idiosyncratic, and hard for many users to understand. This paper describes a machine-independent linker and object language. The linker embodies those linking functions that are machine-independent and centralizes them in a single tool, simplifying…
The design of voltage- or current-controlled active filters with operational transconductance amplifiers (OTA’s) is much less expensive than with analog multipliers. This paper presents some experimental results on known circuits and a new configuration which allows the electronic control of the absolute bandwidth of a…
I visited Michael Fischer at Yale in the spring of 1982. It was known that solutions to the Byzantine generals problem that can handle n Byzantine failures require n+1 rounds of communication. While I was at Yale, Fischer and I proved that this number of…
Grapevine is a multicomputer system on the Xerox research internet. It provides facilities for the delivery of digital messages such as computer mail; for naming people, machines, and services; for authenticating people and machines; and for locating services on the internet. This paper has two…
It is well known that the dramatic developments of the last few years in integrated circuit technology have revolutionised the approach taken to the provision of computer hardware. The use of many microcomputers with substantial amounts of memory is considered routine,and it is quite reasonable…
The study of the physical process of light interacting with matter is an important part of computer image synthesis since it forms the basis for calculations of intensities in the picture. The simpler models used in the past are being augmented by more complex models…
An inexpensive two-quadrant analog voltage divide can be built using an operational transconductance amplifier. The design can be useful in analog tunable and tracking filters and special-purpose modulators and demodulators.
Despite a casual interest in civilian cryptography going back to its origins (see the discussion of [36]), this is my only publication in the field. It presents a cute hack for using a single password to login to a system multiple times without allowing an…
An iterative method for computing shape from shading using occluding boundary information is proposed. Some applications of this method are shown. We employ the stereographic plane to express the orientations of surface patches, rather than the more commonly used gradient space. Use of the stereographic…
This paper describes an algorithm for compressing the spectral representation of an utterance along the time axis while keeping the main features intact. The goal of the algorithm is to save template storage space and to reduce the time required for recognition. For 8 speakers,…
