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The effective operation of free enterprise in creating the envisioned information service industry is dependent upon three accomplishments: (1) the restructuring of our information processing industry so that a clear division of costs is mode among computing, communications, and the development of information services; (2) the wide use of multiaccess system concepts so that information services may share in the use of computer installations and so that the cost of their construction is reasonable; and (3) the development of public, message-switched communications services so that adequate provisions are made for Information security. [ABSTRACT FROM AUTHOR]

The article reports on the fourth symposium of the Association for Computing Machinery, on Operating Systems Principles. For the symposium, over 60 papers were submitted to the program committee in response to a call for papers. From this set, 21 papers were selected for presentation in five formal sessions. Two sessions on the first day of the symposium contained papers describing principles relevant to operating system design and measurement, as well as papers describing complete operating systems. An important focal point of the symposium was the topic of computer security and protection. The banquet speaker, professor Maurice Wilkes of Cambridge University, also emphasized protection. The need to understand the technical aspects of security is particularly urgent in view of the current national attention being given to the social implications of computerized data banks and the rights of citizens. The symposium was co-hosted by the Computer Science Department of Yale University and the Computer Sciences Department of IBM Research Center.

Introduces a series of papers presented at the Association for Computing Machinery's Second Symposium on Symbolic and Algebraic Manipulation held on March 23-25, 1971, in Los Angeles, California. Members of the technical program committee; Titles of papers presented at the symposium.

This article presents several research papers related to computing machinery and computer programs. Designing a system for the analytic processing of mathematical functions around a central syntax processor and permitting the user to work within the context of mathematical syntax leads to a flexible system with a broad range of capabilities. One advantage of the approach mentioned in "A Syntax-Directed Approach to Automated Aids for Symbolic Math," by L. Clapp, is that the basic system can be developed without many a prior restrictions on the nature of the mathematical entities to be processed. Once the basic structure has been developed, the user is free to define and operate within his own system of mathematics by modifying or extending the syntax definitions. In the paper "Programming Languages, Logic and Cooperative Games," by L. Hodes, an application of computers is presented which is not restricted to a single problem area but is perhaps not general purpose enough to be considered programming language, even a problem-oriented one.

The article presents information on the proposed American Standard, "Eleven-Sixteenths Inch Perforated Paper Tape." This standard covers the physical dimensions of the paper tape and its perforations. This standard is for perforated paper tape with fully punched round holes. The punched tape shall have an overall width of 0.686 inch plus or minus 0.003 inch after the tape has been conditioned to within 69.5 degrees F to 76.5 degrees F and 48 percent to 52 percent relative humidity for a period of 24 hours. The tape shall be used for recording up to five levels of information across the tape. The feed holes in the tape shall be fully punched and round with a diameter of 0.046 inch plus 0.002 minus 0.001 inch. All holes punched in the tape shall nominally center on the true intersection of longitudinal and perpendicular transverse center lines spaced 0.100 inch apart. Tolerances on locations of code holes in any one transverse row, relative to the center lines of the feed hole in that row, shall be plus or minus 0.002 inch in the transverse direction and plus or minus 0.003 inch in the longitudinal direction.

The article analyzes existing and proposed American and foreign standards for one inch perforated paper tape for information interchange. This standard covers the physical dimensions of the paper tape and its perforations. The unpunched tape shall have an overall nominal width of 1,000 inch and shall have a nominal thickness of .004 inch. The tape shall be used for recording up to eight levels of information across the tape. The longitudinal center line of the feed holes shall be parallel with the reference edge of the tape and located .392 inch plus or minus .004 inch from the reference edge. The feed holes in the tape shall be fully punched and round with a diameter of .046 inch plus .002 minus .001 inch. The code holes in the tape shall be fully punched and round with a diameter of .072 inch plus or minus .002 inch. All holes punched in the tape shall nominally center on the true intersection of longitudinal and perpendicular transverse center lines spaced .100 inch apart.

The article presents an overview of a series of papers presented at the third Association for Computing Machinery (ACM) Symposium on Operating Systems Principles. They include "TENEX: A Paged Time Sharing System for the PDP-10," by D. G. Bobrow and colleagues, "Synchronization of Communicating Processes," by A. Nico Habermann, "Properties of the Working Set Model," by Peter J. Denning and Stuart C. Schwartz, and "An Operating System Based on the Concept of a Supervisory Computer," by R. S. Gaines.

The article informs that members of the Association for Computing Machinery's annual national conference are happy with the caliber and quantity of the papers received by them for the conference which will be held on August 24-26, 1965 in Cleveland, Ohio. Two years ago, the intensive technical refereeing process was introduced for screening papers for ACM national conferences. Technical papers will be given importance in the conference for the educational benefit of students. Public relations chairman for the conference Raymond F. Hitti is cooperating with professor Lewis Winner in planning the conference.

Outlines various conventions considered for the use of flowchart symbols in the preparation of all types of flowcharts for information processing systems. Application of the conventions to the use of symbols appearing in the proposed American Standard Flowchart Symbols for Information Processing Systems; Symbol text and identification; Representation of multiple media.

Analyzes the proposed American Standard Vocabulary of Information Processing and the Vocabulary of Terms Used in Information Processing developed by the Federation for Information Processing and the International Computation Centre. Influence of earlier works on the vocabularies; Distinctive contributions; Caliber of the technical experts involved and the prestige of the sponsoring organizations.

This article presents information on the winning papers of the first annual ACM Communications Student Paper Competition organized by the Association for Computing Machinery (ACM). First place was given to the paper "Generating Parsers for Affix Grammars," by David R. Crowe of the University of British Columbia. The prize included $250 cash, a trip to ACM 72 to receive the award in person, and a three-year subscription to the ACM serial publication of his choice. Second place was given to the paper "Political Redistricting by Computer," by Robert E. Helbig, Patrick K. Orr, and Robert R. Roediger of Washington University. The prize included $150 cash, and for each author a three-year subscription to the ACM serial publication of his choice. Third place was given to the paper "An Extensible Editor for a Small Machine with Disk Storage," by Arthur J. Benjamin of Brandeis University. The prize included $100 cash, and a three-year subscription to the ACM serial publication of his choice. All of the refereeing of Competition papers was done by graduate students at various colleges and universities.

Comments on author M.L. Patrick's paper related to numerical mathematics. Suggestion of a modification on parallel algorithm.

The article announces awards given to student papers including the "A Learning Program Which Plays Partnership Dominoes," by Michael H. Smith of the University of California, "Fen―An Axiomatic Basis for Program Semantics," by Bruce J. MacLennan of Florida State University, and "Petri Nets and Speed Independent Design," by David Misunas of the Massachusetts Institute of Technology.

Invites research papers for several conferences related to the field of computer science.

Comments on the research paper "Accommodating Standards and Identification of Programming Languages," by Calvin N. Mooers. Opinion that Mooer's approach to programming language via the route of trademark and service mark protection seems ill-advised; Comment that the purpose of the trademark concept is to protect the commercial value of the name of a product, not the integrity of the product itself; View that the most complex thing industrial standardization bodies have ever attempted is the standardization of programming languages.

Since the development of BNF, the definition of the syntax of programming languages has been almost universally associated with context-free requirements. Yet numerous interesting and difficult issues in syntax stem from the context-sensitive requirements, notably the compatibility between the declaration of an identifier and its uses, the correspondence between actual and formal parameters, and issues arising from block structure. This paper explores the use of a formal notation called Production Systems in providing a readable and complete formal definition of syntax. As a practical illustration, a small but significant subset of PL/I is considered. A more detailed presentation, as well as the application to define abstract syntax and translations between languages, is given in a previous paper by the author. [ABSTRACT FROM AUTHOR]

When the shape parameter, α, is integral, generating gamma random variables with a digital computer is straightforward. There is no simple method for generating gamma random variates with non-integral shape parameters. A common procedure is to approximately generate such random variables by use of the so-called probability switch method. Another procedure, which is exact, is due to Jöhnk. This paper presents a rejection method for exactly generating gamma random variables when α is greater than 1. The efficiency of the rejection method is shown to be better than the efficiency of Jöhnk's method. The paper concludes that when α is non-integral the following mix of procedures yields the best combination of accuracy and efficiency: (1) when α is less than 1, use Jöhnk's method; (2) when 1 is less than α and α is less than 5, use the rejection method; (3) when α is greater than 5, use the probability switch method. [ABSTRACT FROM AUTHOR]

This paper introduces the notion of usage counts, shows how usage counts can be developed by algorithms that eliminate redundant computations, and describes how usage counts can provide the basis for register allocation. The paper compares register allocation based on usage counts to other commonly used register allocation techniques, and presents evidence which shows that the usage count technique is significantly better than these other techniques. [ABSTRACT FROM AUTHOR]

This paper modifies an earlier algorithm for converting decision tables into flowcharts which minimize subsequent execution time when compiled into a computer program. The algorithms considered in this paper perform limited search and, accordingly, do not necessarily result in globally optimal solutions. However, the greater search effort needed to obtain a globally optimal solution for complex decision tables is usually not justified by sufficient savings in execution time. There is an analogy between the problem of converting decision tables into efficient flowcharts and the well-understood problem in information theory of noiseless coding. The results of the noiseless coding literature are used to explore the limitations of algorithms used to solve the decision table problem. The analogy between the two problems is also used to develop improvements to the information algorithm in extending the depth of search under certain conditions and in proposing additional conditions to be added to the decision table. Finally, the information algorithm is compared with an algorithm proposed in a recent paper by Verhelst. [ABSTRACT FROM AUTHOR]

The paper describes a scheme for symbolic manipulation of index expressions which arise as a by-product of the symbolic manipulation of expressions in the matrix calculi described by the authors in a previous paper. This scheme attempts program optimization by transforming the original algorithm rather than the machine code. The goal is to automatically generate code for handling the tedious address calculations necessitated by complicated data structures. The paper is therefore preoccupied with "indexing by position." The relationship of "indexing by name" and "indexing by position" is discussed. [ABSTRACT FROM AUTHOR]

This article presents information on various activities organized by the Association for Computing Machinery (ACM). The Fifth Annual Microprogramming Workshop will be held in the Illini Union of the University of Illinois at Urbana-Champaign on September 25 and 26. Sponsored by the ACM Special Interest Group on Microprogramming and the 555 Computer Society, this workshop provides a leading forum where active workers in the microprogramming area can hear several formal papers and participate in informal discussion groups oriented to specific topics. Professor Daniel L. Slotnick, director of the Center for Advanced Computation at the University of Illinois at Urbana-Champaign, will be the featured speaker at a banquet on September 25; his topic will be "Parallel Processing." The 1973 San Diego Biomedical Symposium will be held January 31 through February 2, 1973, at the Sheraton-Harbor Island Hotel, San Diego, California. The Symposium theme will be "Innovations in Biomedicine." Technical papers appropriate to the following sessions are invited: aids to clinical care, modeling and analysis, interpretation and data reduction, scanning and image processing, information engineering, and general innovations.

Affix grammars are two-level grammars which are similar to van Wijngaarden's two-level grammars used in the definition of Algol 68. Affix grammars are shown by Koster to be equal in power to van Wijngaarden grammars. They are much more suited to parsing than are the latter, however. Koster, the inventor of affix grammars, suggests a top-down scheme for parsing them, based on recursive procedures. This paper presents a bottom-up scheme for parsing them, based on an extension of Floyd Production Language (FPL). Included is an algorithm, similar to that of DeRemer's, for converting a large class of affix grammars into FPL. The paper concludes by discussing briefly the applicabilities of the conversion algorithm and affix grammars in general, and some possible extensions to Koster's definition of affix grammars. [ABSTRACT FROM AUTHOR]

This paper discusses both the history and future of programming languages (= higher level languages). Some of the difficulties in writing such a history are indicated. A key part of the paper is a tree showing the chronological development of languages and their interrelationships, Reasons for the proliferation of languages are given. The major languages are listed with the reasons for their importance. A section on chronology indicates the happenings of the significant previous time periods and the major topics of 1972. [ABSTRACT FROM AUTHOR]

Clenshaw-Curtis quadrature is a particularly important automatic quadrature scheme for a variety of reasons, especially the high accuracy obtained from relatively few integrand values. However, it has received little use because it requires the computation of a cosine transformation, and the arithmetic cost of this has been prohibitive. This paper is in two parts; a companion paper, "II Computing the Cosine Transformation," shows that this objection can be overcome by computing the cosine transformation by a modification of the fast Fourier transform algorithm. This first part discusses the strategy and various error estimates, and summarizes experience with a particular implementation of the scheme. [ABSTRACT FROM AUTHOR]

In a companion paper to this, "I Methodology and Experiences," the automatic Clenshaw-Curtis quadrature scheme was described and how each quadrature formula used in the scheme requires a cosine transformation of the integrand values was shown. The high cost of these cosine transformations has been a serious drawback in using Clenshaw-Curtis quadrature. Two other problems related to the cosine transformation have also been troublesome. First, ... conventional computation of the cosine transformation by recurrence relation is numerically unstable, particularly at the low frequencies which have the largest effect upon the integral. Second, in case the automatic scheme should require refinement of the sampling, storage is required to save the integrand values after the cosine transformation is computed. This second part of the paper shows how the cosine transformation can be computed by a modification of the fast Fourier transform and all three problems overcome. The modification is also applicable in other circumstances requiring cosine or sine transformations, such as polynomial interpolation through the Chebyshev points. [ABSTRACT FROM AUTHOR]

Because of the problems created by the explosion of papers in the mathematical sciences and the drawbacks that this places on research, it is suggested that a tree of all mathematical results and terminology be maintained in a multiterminal computer system. Users of the system can store in the computer an updated file of their current knowledge, and on selecting a paper to read, they can obtain from the computer the minimum subtree of theorems required to bring them from what they already know to the background knowledge which the paper assumes. Under certain conditions, means are also provided for the contribution of useful comments by the readers of a work and for interaction between commentators and with the author. This paper describes how the system can be organized and the role required of readers, writers, and commentators. [ABSTRACT FROM AUTHOR]

In this paper the Ritz-Trefftz algorithm is applied to the computer solution of the state regulator problem. The algorithm represents a modification of the Ritz direct method and is designed to improve the speed of solution and the storage requirements to the point where real-time implementation becomes feasible. The modification is shown to be more stable computationally than the traditional Ritz approach. The first concern of the paper is to describe the algorithm and establish its properties as a valid and useful numerical technique. In particular such useful properties as definiteness and reasonableness of condition are established for the method. The second part of the paper is devoted to a comparison of the new techniques with the standard procedure of numerically integrating a matrix Riccati equation to determine a feedback matrix. The new technique is shown to be significantly faster for comparable accuracy. [ABSTRACT FROM AUTHOR]

This section provides summaries of papers on algorithms. The paper "Function Minimization and Linear Search," by K. Fielding discusses a procedure that minimizes a function using the method of Broyden. The parameters of the procedure include iterations, maxiters, and tolerance. In his paper "Binary Ordered Walsh Functions," H. Hübner explains the procedure binwal which computes the binary ordered Walsh function. The paper "Simpson's Rule for Multiple Integration" states that an algorithm can be marginally improved by replacing each integer constant to its equivalent decimal number.

The article presents several research papers relating to algorithms. The paper "Greatest Common Divisor of n Integers and Multipliers" presents an algorithm which calculates the greatest common divisor, IGCD, of n integers. Details of the method and comparisons to other algorithms are also given. The algorithm is a new version of the Euclidean algorithm for n integers. The n-1 calculations of the greatest common divisor of two integers is accomplished by means of a modified version of the Blankinship algorithm. The paper "Exponential Integral Ei (x)" presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract NAS7-100, sponsored by the National Aeronautics and Space Administration. It presents an algorithm which was compiled and executed without any modification on a UNIVAC 1108 computer. An unfortunate precedent has been set in several recent algorithms of using an illegal FORTRAN construction.

A comprehensive system for transformational grammar has been designed and implemented on the IBM 360/67 computer. The system deals with the transformational model of syntax, along the lines of Chomsky's Aspects of the Theory of Syntax. The major innovations include a full, formal description of the syntax of a transformational grammar, a directed random phrase structure generator, a lexical insertion algorithm, an extended definition of analysis, and simple problem-oriented programming language in which the algorithm for application of transformations can be expressed. In this paper we present the system as a whole, first discussing the general attitudes underlying the development of the system, then outlining the system and discussing its more important special features. References are given to papers which consider some particular aspect of the system in detail. [ABSTRACT FROM AUTHOR]

Two recent papers, one by Hansen and one by Hansen and R. R. Smith, have shown how interval Arithmetic (I.A.) can be used effectively to bound errors in matrix computations. In the present paper a method proposed by Hansen and R. R. Smith is compared with straightforward use of I.A. in determinant evaluation. Computational results show the accuracy and running times that can be expected when using I.A. for determinant evaluation. An application using I.A. determinants in a program to test a set of functions to see if they form a Chebyshev system is then presented. [ABSTRACT FROM AUTHOR]

Sussenguth suggests in a paper (1963) that a file should be organized as a doubly-chained tree structure if it is necessary both to search and to update frequently. Such a structure provides a compromise between the fast search/slow update characteristics of binary searching and the slow search/fast update characteristics of serial searching. His method, however, contains the limiting restriction that all terminal nodes lie on the same level of the tree. This paper considers the effect of relaxing this restriction. First, trees which have the property that a priori the filial set of each node is well defined are studied. It is proved that coding the nodes within each filial set with respect to the number of terminal nodes reachable from each is necessary and sufficient to guarantee minimum average search time. Then the more general case (that is, where the entire structure of the tree is changeable) is treated. A procedure is developed for constructing a tree with a minimum average search time. A simple closed expression for this minimum average search time is obtained as a function of the number of terminal nodes. The storage capacity required to implement the doubly-chained tree structure on a digital computer is also determined. Finally, the total cost of the structure, using Sussenguth's cost criterion, is computed. It is shown that significant improvements in both the average search time and the total cost can be obtained by relaxing Sussenguth's restriction that all terminal nodes lie on the same level of the tree. [ABSTRACT FROM AUTHOR]

This article focuses on the Association for Computers Machinery (ACM) 1968 National Conference and Exposition that was held during August 27-29, 1968 in Las Vegas, Nevada. A keener recognition of member interest and professional responsibilities characterizes the spirit in which the Conference Program for ACM68 was organized. Appropriately, technical and special sessions of timely and practical concern to the information processing; community have been planned for Conference attendees. The Program Committee has worked with ACM Special Interest Groups (SIG) and Special Interest Committees (SIC) in an effort to integrate SIG/SIC efforts with the aim of presenting a distinguished program. By developing sessions with the cooperation of ACM SIG's and SIC's, the Program Committee has attempted to evolve a program which is most responsive to the needs of the ACM membership. SIG and SIC also assisted the Program Committee by encouraging their members to develop and submit papers, and by advising the SIC on the newest developments in each special interest area. Further, they were able to provide knowledge and guidance to the SIC for the selection of session chairmen and technical paper referees.

Session 19 of the ACM 20th Anniversary Conference on August 31, 1967, was entitled Education, Design Experiments, and Computer Appreciation. Its second half consisted of a panel discussion on computer appreciation, organized and chaired by Elliott I. Organick. The four panelists were Charles H. Davidson, Bernard A. Goller, Richard W. Hamming, and Alan J. Perlis. After making prepared statements, the panelists were joined in discussion by Andries van Dam and Arthur B. Kohn, who had presented papers in the first half. This is a transcript of the panel discussion, condensed by Dr. Organick and edited by him and the panelists. Same remarks referred to papers by van Dam and Kahn or to the discussion during the first half of the session. Pertinent papers are included in the references. [ABSTRACT FROM AUTHOR]

The American Standard Code for Information Interchange (ASCII) contains a number of control characters associated with the principle of code extension, that is, with the representation of Information which cannot be directly represented by means of the characters in the Code. The manner of use of these characters has not previously been completely described. This paper presents a set of mutually consistent philosophies regarding code extension applications, and suggests a corollary set of doctrines for the application of the code extension characters. Distinctions are drawn between code extension and such other concepts as "graphic substitution" or "syntactic representation" which are often used to meet similar requirements. Also covered are certain topics which are not truly concerned with code extension but which are often linked with it in discussion on code applications. The material In this paper is equally applicable in principle to the (proposed) ISO international 7-bit code for information interchange. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present a comparison of some computer simulation languages and of some of the packages by which each is implemented. Some considerations involved in comparing software packages for digital computers are discussed In Part I. The issue is obvious: users of digital computers must choose from available languages or write their own. Substantial costs can occur, particularly in training, implementation and computer time if an inappropriate language is chosen. More and more computer simulation languages are being developed: comparisons and evaluations of existing languages are useful for designers and implementers as well as users. The second part is devoted to computer simulation and simulation languages. The computational characteristics of simulation are discussed with special attention being paid to a distinction between continuous and discrete change models. Part III presents a detailed comparison of six simulation languages and packages: SIMSCRIPT, CLP, CSL, GASP, GPSS and SOL. The characteristics of each are summarized in a series of tables. The implications of this analysis for designers of languages, for users, and for implementers are developed. The conclusion of the paper is that the packages now available for computer simulation offer features which none of the more general-purpose packages do and that analysis of strengths and weaknesses of each suggests ways in which both current and future simulation languages and packages can be improved. [ABSTRACT FROM AUTHOR]

In the first part of the paper, flow diagrams are introduced to represent inter al. mappings of a set into itself. Although not every diagram is decomposable into finite number of given base diagrams, this becomes true at a semantical level due to o suitable extension of the given set and of the basic mappings defined in it. Two normalization methods of flow diagrams are given. The first has three base diagrams; the second, only two. In the second part of the paper, the second method is applied to the theory of Turing machines. With every Turing maching provided with a two-way half-tape, there is associated similar machine, doing essentially the same job, but working on a tape obtained from the first one by interspersing alternate blank squares. The new machine belongs to the family, elsewhere introduced, generated by composition and iteration from the two machines χ and R. That family is proper subfamily of the whole family of Turing machines. [ABSTRACT FROM AUTHOR]

The aim of this paper is to provide background information on the existing literature on experimental design techniques which may be applicable to the design of computer simulation experiments for industrial systems. Although major emphasis is placed on analysis of variance techniques, three other techniques of data analysis are considered—multiple ranking procedures, sequential sampling and spectral analysis. The paper treats four specific experimental design problems and several techniques for solving them. The four experimental design problems are: (1) the problem of stochastic convergence, (2) the problem of factor selection, (3) the problem of motive and (4) the many response problem. [ABSTRACT FROM AUTHOR]

One of the most salient characteristics of extensible machines (EM) is the facility for providing system control over program-to-program and program-to-data linkage (e.g., address connection). It is the intent of this paper to expand and clarify the remarks concerning program-to-program and program-to-data linkage that were embodied in the authors' previous paper on the EM concepts, and to, finally, trace the employment of linkage mechanisms through various levels of programming languages. [ABSTRACT FROM AUTHOR]

This paper describes how some of the semantics of ALGOL 60 can be formalized by establishing a correspondence between expressions of ALGOL 60 and expressions in a modified form of Church's λ-notation. First a model for computer languages and computer behavior is described, based on the notions of functional application and functional abstraction, but also having analogues for imperative language features. Then this model is used as an "abstract object language" into which ALGOL 60 is mapped. Many of ALGOL 60's features emerge as particular arrangements of a small number of structural rules, suggesting new classifications and generalizations. The correspondence is first described informally, mainly by illustrations. The second part of the paper gives a formal description, i.e. an "abstract compiler" into the "abstract object language." This is itself presented in a "purely functional" notation, that is one using only application and abstraction. [ABSTRACT FROM AUTHOR]

Invites research publications for various conferences on computer science that will be held in the coming months.

The article offers information about the 21st National Conference of the Association for Computing Machinery to be held in Los Angeles, California, from August 30 to September 1, 1966.

A previous paper presented an efficient algorithm, called the Recomputation Algorithm, for evaluating a rational expression to within any desired tolerance on a computer which performs variable-precision arithmetic operations. The Recomputation Algorithm can be applied to expressions involving any variable-precision operations having O(10-... + Σ ∣ε∣) error bounds, where p denotes the operation's precision and ε, denotes the error in the operation's with argument. This paper presents an efficient variable-precision exponential operation with an error bound of the above order. Other operations, such as log, sin, and cos, which have simple series expansions, can be handled similarly. [ABSTRACT FROM AUTHOR]

The article presents news related to the Association for Computing Machinery (ACM). The new position of Director of Administration has been established at ACM Headquarters and Joseph Saetta has been hired to fill it. The position collects into one department the activities of three units which were previously in different department. They are--first, the unit which handles all membership, subscription, and single copy transactions; second, the unit which handles purchasing, the stock room, and incoming and outgoing mail; and third, the accounting unit. The Second ACM Symposium on Symbolic and Algebraic Manipulation will be held on March 23-25, 1971, at the International Hotel in Los Angeles, California. The Special Interest Group on Symbolic and Algebraic Manipulation is sponsoring the symposium, with the Special Interest Group on Artificial Intelligence as a co-sponsor. The symposium will cover developments in the field in the past five years. A number of sessions of contributed papers are scheduled, and approximately ten invited tutorial papers will survey key subject areas. The symposium will be of interest to users of both symbolic and manipulation systems as well as to system developers.

An efficient method of ordered retrieval of binary words from an associative memory, as described by Lewin, is based on the case of special readout circuits which indicate the digit values present in the individual digit columns of the memory. Thus the circuits indicate whether the individual digit columns contain digits of both values, or of only one value, or contain no digits at all (i.e. that the memory is empty). The use of these circuits, which in this paper are termed column value indicators, reduces considerably the number of memory accesses necessary to retrieve in order a number of distinct binary words from the memory. Lewin proves that, for the readout by the described method of m distinct binary words, 2m-1 memory accesses are necessary. (Thus he proves that the number of necessary memory accesses of his method, unlike those of other methods, is independent of the word length.) In this paper a very simple proof of this theorem derived from some elementary aspects of the structure of sets of binary numbers is presented. [ABSTRACT FROM AUTHOR]

The article presents information on various chapters of the Association for Computing Machinery (ACM) across the U.S. The Greater Rio Grande Chapter of ACM has recently extracted from its files a list of the titles of all technical papers presented at Chapter meetings since its inception in 1957. Using a program developed by D.K. Robbins of Sandia Corp., a KWIC-type listing of permuted titles of these papers has been made. This listing has been distributed to all members of the Chapter. Topics and speakers at ACM Chapters across the U.S. indicate the current trends of interest in computer science and data processing. The ACM Tidewater Chapter is sponsoring this spring a professional development course on "Real-Time Computing." The course is given by the Chapter's professional development chairman, Cecil Frost, who is applications staff specialist for Control Data Corp. At its April 21, 1966 meeting, the Westchester-Fairfield Chapter heard William Orchard-Hays speak on "Linear Programming of Computational Techniques."

As linear programming models grow bigger and bigger in size, much actual data that must be memorized is often put on magnetic tape or disk, and consequently there is an improportionately fast rise in the consumption of computer time. To cut down this expense, on ever increasing effort Is mode to design more efficient algorithms. This paper is meant to support the effort. If is attempted to find some characteristics of the way pivot column is found. The number of repetitions of a certain transfer of data from tape to core memory is considered. After some simplification, the problem is restated in a general way. The generating function of the probability distribution and the moment generating function of the number of repetitions is found. Asymptotic formulas are given for the moments using result from a paper of S. Narumi [1]. The results may be applied to write very efficient routines that search for an extreme value in a table. Formulas provide a means of calculating the computer timings in this case. [ABSTRACT FROM AUTHOR]

The use of the Kleene regular expression notation for describing algebraic language syntax, in particular of ALGOL is described in this paper. A FORTRAN II computer program for carrying out the elimination algorithm of Gorn, similar to Gaussian elimination for linear systems of algebraic equations, is described. This was applied to numerous smaller languages, including some sublanguages of ALGOL. A hand calculation result of the application of the algorithm to all of ALGOL is given, thus expressing the Revised ALGOL 1960 syntax in completely nonrecursive terms, as far as its context-free portion is concerned. This description in many ways is far more intuitively understood than the previous recursive description, it is suggested. The paper also includes results of the machine program, which does not include a simplification algorithm. [ABSTRACT FROM AUTHOR]

Sequencing to minimize mean finishing time (or mean time in system) is not only desirable to the user, but it also tends to minimize at each point in time the storage required to hold incomplete tasks. In this paper a deterministic model of independent tasks is introduced and new results are derived which extend and generalize the algorithms known for minimizing mean finishing time. In addition to presenting and analyzing new algorithms it is shown that the most general mean-finishing-time problem for independent tasks is polynomial complete, and hence unlikely to admit of a non-enumerative solution. [ABSTRACT FROM AUTHOR]

Virtual machine systems have been implemented on a limited number of third generation computer systems, e.g. CP-67 on the IBM 360/67. From previous empirical studies, it is known that certain third generation computer systems, e.g. the DEC PDP-10, cannot support a virtual machine system. In this paper, model of a third-generation-like computer system is developed. Formal techniques are used to derive precise sufficient conditions to test whether such an architecture can support virtual machines. [ABSTRACT FROM AUTHOR]