Maclisp extensions

A common subset of selected facilities available in Maclisp and its derivatives (PDP-10 and Multics Maclisp, Lisp Machine Lisp (Zetalisp), and NIL) is decribed. The object is to add in writing code which can run compatibly in more than one of these environments

Experimental evaluation of CONIT in DGIS gateway environment

Includes bibliographical references (p. 12).Final report.Supported by the Logistics Management Institute with the Dept. of Defense for the Defense Technical Information Center. MDA903-85-0139 DL605/01Richard S. Marcus

A public access information system for the Hudson River Foundation

Bibliography: leaves 25-26.3/84X/4 4/84X/4by Richard S. Marcus

A knowledge-based system approach to helping engineers understand codes of practice

Civil engineers are increasingly called upon to design according to codes of practice which are foreign, or otherwise unfamiliar to the engineer. Some form of 'tool' to aid such engineers in the safe and effective use of unfamiliar codes, is therefore highly desirable. The argument presented in this thesis, is that a specialised 'knowledge-based system' (KBS) can be successfully constructed in order to provide various sons of insights into the design methods used in certain codes of practice. Three key ideas were used in the implementation produced during the research: the development of a novel set of complementary 'facilities' for examining the design methods used in codes; the support of comparison between the examination of two different codes; and ensuring the system's representation of codes and their examination, could be made readily comprehensible to engineers by using familiar human language phrases. Seven different facilities were developed in the research, including: the ability to view the codes installed in the system in a form close to a human language (such as English or French); the ability to perform parts of a code-based design procedure to various levels of detail; and the ability to inspect the interdependences of design parameters within codes. Use of these symbolic and numerical methods could provide the engineer with the information required to understand how and why an unfamiliar code would specify surprising, or otherwise unusual design parameters in some particular situation. They could also be used in a more exploratory fashion, with t1ie same broad aim of greater understanding of an unfamiliar code. A KBS is a sophisticated computer program that uses the idea of processiilg knowledge information. A characteristic feature of KBSs is that one of their primary components is a 'knowledge base' - a store of human expertise. The KBS built in this research, 'COPES' used an existing abbreviated form of the reinforced concrete (RC) beam design codes as its knowledge base. In particular, it contained 'procedural knowledge'. COPES was implemented using conventional computer systems and progranuning languages (pascal and FORTRAN on a Sun workstation). This is in contrast to most contemporary KBSs, which are often built using a 'shell', or an unconventional declarative programming language such as Prolog. One reason for this choice was that COPES used parts of previous computing work done with RC beam design codes, that had also used conventional computing techniques. However, our research did cover an investigation into the prospects for an alternative approach using a modem expert system shell. (It was confirmed that such an approach was generally less suitable in this particular application.) The COPES system proved to be a useful prototype 'toolbox' of various procedural knowledge extraction operations, which could help an engineer's understanding of an unfamiliar code of practice. To provide a practical system, the various explanatory methods developed could potentially be incorporated into an overall CAD (Computer-Aided Design) environment, or alternatively, wrapped up in a more sophisticated interactive program

Garbage Collection in a Very Large Address Space

This research was done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology and was supported by the Office of Naval Research under contract number N00014-75-C-0522.The address space is broken into areas that can be garbage collected separately. An area is analogous to a file on current systems. Each process has a local computation area for its stack and temporary storage that is roughly analogous to a job core image. A mechanism is introduced for maintaining lists of inter-area links, the key to separate garbage collection. This mechanism is designed to be placed in hardware and does not create much overhead. It could be used in a practical computer system that uses the same address space for all users for the life of the system. It is necessary for the hardware to implement a reference count scheme that is adequate for handling stack frames. The hardware also facilitates implementation of protection by capabilities without the use of unique codes. This is due to elimination of dangling references. Areas can be deleted without creating dangling references.MIT Artificial Intelligence Laboratory Department of Defense Office of Naval Researc

Data management system study Final technical report, 15 May 1967 - 31 Mar. 1968

Systems design of prototype coherent system to meet data processing requirements of post-Apollo mission

Expert retrieval assistance development and experimentation

Caption title.Bibliography: leaves 8-9.Supported, in part, by a grant from the National Library of Medicine. LM-03210 Supported, in part, by a grant from the National Science Foundation. IST-84-14485 Supported, in part, by the Logistics Management Institute in conjunction with the Defense Technical Information Center.Richard S. Marcus

Computer security in an educational environment.

Massachusetts Institute of Technology, Alfred P. Sloan School of Management. Thesis. 1973. M.S.MICROFICHE COPY ALSO AVAILABLE IN DEWEY LIBRARY.Includes bibliographical references.M.S

Complexity Information Flow in a Multi-threaded Imperative Language

We propose a type system to analyze the time consumed by multi-threaded imperative programs with a shared global memory, which delineates a class of safe multi-threaded programs. We demonstrate that a safe multi-threaded program runs in polynomial time if (i) it is strongly terminating wrt a non-deterministic scheduling policy or (ii) it terminates wrt a deterministic and quiet scheduling policy. As a consequence, we also characterize the set of polynomial time functions. The type system presented is based on the fundamental notion of data tiering, which is central in implicit computational complexity. It regulates the information flow in a computation. This aspect is interesting in that the type system bears a resemblance to typed based information flow analysis and notions of non-interference. As far as we know, this is the first characterization by a type system of polynomial time multi-threaded programs