Original Symbols Research Articles

Current Abstracts

The following abstracts of current documents in library and information science are edited versions of entries from Library and Information Science Abstracts ( LISA) reproduced with the permission of the Editor, Nicholas L. Moore. The aim of this listing is to draw the attention of Information Development readers to documents which are international in scope, particularly those dealing with the problems of the developing countries. Items from Information Development itself are excluded, since a list of articles which have appeared in previous issues is published in the journal from time to time when space permits. The entries have been arranged in a broadly geographical sequence, with the original classification symbols and reference numbers appended to facilitate reference of the entries in LISA, which also provides alphabetical name and subject indexes and an outline of the classification scheme. Would readers please note that enquiries regarding the documents listed here should be addressed to the publisher concerned, not to the Information Development editorial office or to Mansell Publishing. In case of difficulty, publishers' addresses may be obtained from LISA at the address given below.

Evaluation of a Proposed Space and Missile Warning Symbology Standard for Graphical Displays

A discriminability evaluation was performed on a proposed Space and Missile Warning symbol set. Our analysis focused on the discriminability of the symbols and the application of the information coding techniques. Inconsistent or inappropriate use of coding techniques can affect a user's interpretation of the symbol's intended meaning. Potential problems included the similarity of individual symbols, use of alphanumeric markers and partially shaded symbols, and the lack of guidance on the minimum size of the symbols. After a lengthy review of previous research, we felt the literature could not provide adequate solutions. A two-part discriminability study was conducted to test the overall effects of the information coding techniques on discriminability, to identify individual symbols with low discriminability, and to determine an appropriate minimum size for these symbols. Search time was used as a measure of symbol discriminability. Size, shape, markers, and shading had significant effects on search time and errors. The experiments confirmed the suspected discriminability problems and modifications were made to the existing symbol set to create three new alternative symbol sets. Testing performed on these new symbol sets revealed that many of the problem areas from the original symbol set had been improved. Design guidelines and a new modified symbol set were proposed for review by the operational community.

Current Research Summaries

The following descriptions of current research projects in library and information science are edited versions of entries from Current Research in Library and Information Science, reproduced withe the permission of the Editor, Pirkko Elliott. The aim of this listing is to draw the attention of Information Development readers to research projects which are international in scope, particularly those dealing with the problems of the developing countries. Some elements of the original entries, such as details of project duration and sources of funding, have been omitted in order to save space. The entries have been arranged in broadly geographical sequence, with the original classification symbols and reference numbers appended to facilitate reference to the full entries in Current Research, which also provides the full addresses of research workers and/or institutions, together with an alphabetical subject index and a separate list of sub- doctoral theses and dissertations.

Current Abstracts

The following abstracts of current documents in library and information science are edited versions of entries from Library and Information Science Abstracts (LISA) reproduced with the permission of the Editor, Nicholas L. Moore. The aim of this listing is to draw the attention of Information Development readers to documents which are international in scope, particularly those dealing with the problems of the developing countries. Items from Information Development itself are excluded, since a list of articles which have appeared in previous issues is published in the journal from time to time when space permits. The entries have been arranged in a broadly geographical sequence, with the original classification symbols and reference numbers appended to facilitate reference of the entries in LlSA, which also provides alphabetical name and subject indexes and an outline of the classification scheme. Would readers please note that enquiries regarding the documents listed here should be addressed to the publisher concerned, not to the Information Development editorial office or to Mansell Publishing. In case of difficulty, publisher's addresses may be obtained from LISA at the address given below.

A Huffman-type code generator with order-N complexity

A new method with order-N complexity is presented to construct Huffman-type minimum-redundancy codes for N distinguished symbols in the source alphabets. This method includes a contraction process as well as an expansion process. The contraction process has (N-3) contraction stages. To reduce the data-transfer operations, (N-5) vacancies are reserved beforehand in the array which is used to store the probabilities of symbols. At each contraction stage, the number of the symbols whose probabilities are equal to or less than the sum of the two least probabilities is stored and named as the expansion index. Under the contraction process, the code lengths of the original symbols and those at each contraction stage increase monotonically. Since the proposed method gives a monotonically increasing code both in code length and in code value, its implementation becomes easy in VLSI technology, in microprocessor-based systems, or in software programming. >

COORDINATE GRAMMARS REVISITED: GENERALIZED ISOMETRIC GRAMMARS

In a "coordinate grammar", the rewriting rules replace sets of symbols having been given coordinates by sets of symbols whose coordinates are given functions of the coordinates of the original symbols. It was shown in 1972 that coordinate grammars are "too powerful"; even if the rules are all of finite-state types and the functions are all computable by finite transducers, the grammar has the power of a Turing machine. This paper shows that if we require the functions to be shift-invariant and the rules to be of bounded diameter, then such grammars do have a useful hierarchy of types; in fact, when we require that their sentential forms always remain connected, they turn out to be equivalent to "isometric grammars".

Clash of Symbols—The AMA Stone in the Washington Monument: Hippocratectomy or Hippocratoplasty?

To the Editor.— It is fitting for the American Medical Association (AMA) to launch a fund to create a symbol of American medicine to be displayed by the National Park Service. But its choice of the same inappropriate symbol it selected over 100 years ago is disappointing. 1 The original symbol was a sculpture of Hippocrates refusing to give medical aid to an enemy of his homeland. The 19th-century American physician considered patriotic the attitude that the physician was the servant of the state before being the servant of humanity. (Perhaps this attitude contributed to the imprisonment of Dr Mudd because he gave medical aid to President Lincoln's assassin.) Today, however, I think most American physicians would consider the old attitude chauvinistic, unethical, uncharitable, and mean. The original sculpture by Beck, whom posterity has judged to have been without talent and imagination, was a translation into stone of a painting

A computer aided method for symbolic transfer function determination

Abstract To find the corresponding transfer function of a state space model is straightforward ; however, when the system is large, and also we want the original symbols to be preserved, the problem is not a simple one, even with the aid of a computer. In fact, state space models, especially for large dimensional cases, frequently involve sparse matrices. For simplifying the calculation, we should take advantage of the sparse property ; otherwise, the problem will be unnecessarily complicated. This paper mainly uses the outer product in the Grassmann sense to solve the sparse determinant symbolically.

Automatic Digital Programming of Analog Computers

A digital technique for manipulating symbols defining a mathematical expression is introduced and it is shown how this technique can be applied so that a digital computer can automatically compile an analog computer program directly from a mathematical description of the problem to be solved. The mathematical problem considered is that of solving a system of nonlinear first-order differential equations with initial conditions. It is assumed that these equations have been prescaled and are expressed in terms of the physical variables rather than the original mathematical variables. A resume of a method for reducing the original symbol sequence defining the differential equations to symbol subsequences from which the analog program can be formed is given. It is then shown how the analog program is to be generated from these symbol sequences. To illustrate the detailed application of the technique an analog program is compiled for a particular system of differential equations.

The Share 709 System: Machine Implementation of Symbolic Programming

As emphasized in the preceding paper, a fundamental requirement for effective utilization of high speed computing devices such as the 709 is a man-machine communication link that is at once rapid a...