March 1980 - Vol. 23 No. 3

March 1980 issue cover image


Research and Advances

General considerations on the design of an interactive system for data analysis

Among the most important criteria in the design and implementation of an interactive system for data analysis are: data structure, control language, user interface, sytem versatility, extensibility, and portability. The design of an interactive system, viewed as a set of constrained decisions based on these criteria, will be discussed. The concepts and considerations discussed in this article about the design of interactive systems are general in nature and are neither problem-specific nor discipline-specific. Specific examples from statistical packages and their designs are cited for illustration purposes only.
Research and Advances

A generalized text editor

Text is not the only data that needs editing; for example, file deletion utilities edit directories. If all “editors” used the same command language, they would be easier to learn, remember, and code. This paper describes a generalized editor that edits text, directories, binary core images, and certain operating system data with a single user interface.
Research and Advances

A linear algorithm for copying binary trees using bounded workspace

An algorithm to copy a binary tree in linear time using bounded workspace is presented. The algorithm does not modify the original tree at any time. The copy is constructed in such a way that it can be traversed in a read-only fashion even before the copying process is complete, provided one can distinguish between the original and the copy. The traversal can be carried out in parallel with the copying.
Research and Advances

Region representation: boundary codes from quadtrees

There has been recent interest in the use of quadtrees to represent regions in an image. It thus becomes desirable to develop efficient methods of conversion between quadtrees and other types of region representations. This paper presents an algorithm for converting from quadtrees to a simple class of boundary codes. The algorithm is shown to have an execution time proportional to the perimeter of the region.

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