Copy Link
Add to Bookmark
Report
AIList Digest Volume 4 Issue 213
AIList Digest Tuesday, 14 Oct 1986 Volume 4 : Issue 213
Today's Topics:
Query - Public Domain Software for Expert Systems,
Expert Systems - Getting Started,
AI Tools - Garbage Collection
----------------------------------------------------------------------
Date: 11 Oct 86 22:06:27 GMT
From: ulysses!mhuxr!mhuxt!houxm!hou2d!meh@ucbvax.Berkeley.EDU (P.MEHROTRA)
Subject: Public Domain Software for Expert Systems
Public Domain Software for Expert Systems
for building expert systems. I work in Unix environment and
have Franz LISP on my system. I already have OPS5. I am especially
interested in tools which use frames and/or semantic networks
for knowledge representation.
Any software or any information where I can get this software
will be greatly appreciated.
Prem K Mehrotra
hou2d!meh speedy!prem
201-615-4535
------------------------------
Date: 12 Oct 86 19:18:22 GMT
From: well!jjacobs@LLL-LCC.ARPA (Jeffrey Jacobs)
Subject: Getting started in Expert Systems
> lem@galbp.UUCP
> Lisa Meyer has requested information on expert systems, PD and PC related
> tools.
Lisa,
I suggest that you start with Waterman's "A Guide to Expert Systems", as
well as looking in your University book store and local commercial
book stores and computer stores. This will give you a working bibliography
to pursue.
Most tools listed in the Waterman book are public domain and can often
be obtained from the respective institution for a nominal price (usually of a
tape).
Periodicals include IEEE Expert (quarterly), AI Expert (monthly), SIGART
(ACM Sig on AI), and AI Magazine (AAAI, quarterly). Also, see the July 86
issue of Computer (IEEE Computer Society).
There are a number of PC tools and languages available. Best place to look
is Byte magazine and various PC magazines. There are a number of LISPs,
PROLOGs and a good Smalltalk available. TI has SCHEME and 2 levels
of Personal Consultant. Insight-2+ has also received good reviews.
For Public Domain PC software, I suggest the CompuServe Information
Service (CIS). There is a Forum sponsored by AI Expert magazine which
has a great deal of PD tools. It's also a great place for getting information
oriented towards PC's.
Also, the following BBS'es:
Boston, Mass. (Common Lisp Group) (617) 492-2399
Woodbury, Conn. (203) 263-5783
Jeffrey M. Jacobs
CONSART Systems Inc.
Technical and Managerial Consultants
P.O. Box 3016, Manhattan Beach, CA 90266
(213)376-3802
CIS:75076,2603
BIX:jeffjacobs
USENET: well!jjacobs
------------------------------
Date: 6 Oct 86 02:38:00 GMT
From: osiris!chandra@uxc.cso.uiuc.edu
Subject: Re: Expert System Wanted
There is no General Purpose expert system in the world.
If you find one, you will probably get the Turing Award.
I will be very happy to recieve more information about
General Purpose Expert Systems. A breakthrough I am looking
forward to.
Please excuse my ignorance about this new technology.
Thanks.
Navin Chandra
MIT
------------------------------
Date: 9 Oct 86 12:21:00 GMT
From: osiris!chandra@uxc.cso.uiuc.edu
Subject: Re: Expert System Wanted
Hi,
FOUND!
There is an expert system shell for CMS. It is called PRISM.
PRISM is also called ESE (expert system environemnt).
It has production rule based programming and a interesting control
structure based on Focus Control Blocks (with inheritance)
ESE is available from IBM itself. It is written in lisp and was most
probably developed at IBM Watson Research Labs.
Navin Chandra
MIT
------------------------------
Date: Mon, 6 Oct 86 10:02:17 cdt
From: preece%ccvaxa@gswd-vms.ARPA (Scott E. Preece)
Subject: Xerox vs Symbolics -- Reference coun
> From: Dan Hoey <hoey@nrl-aic.ARPA>
> Let me first deplore the abuse of language by which it is claimed that
> Xerox has a garbage collector at all. In the language of computer
> science, Xerox reclaims storage using a ``reference counter''
> technique, rather than a ``garbage collector.'' This terminology
> appears in Knuth's 1973 *Art of Computer Programming* and originated in
> papers published in 1960. I remain undecided as to whether Xerox's
> misuse of the term stems from an attempt at conciseness, ignorance of
> standard terminology, or a conscious act of deceit.
----------
Hoey's pedantic insistence on a precision which does not exist in
the "standard terminology" is apparently also an incorrect
characterization of the Xerox approach, which [from the
descriptions I have read] combines some aspects of the "pure"
reference counting approach described by Knuth and some
aspects of "pure" garbage collection.
The Deutsch paper [CACM, 9/76] explicitly separates the two kinds of
storage reclamation techniques and then proposes a combined method
with features of both.
In fact, however, the distinction on which Hoey places
so much importance seems to have mostly vanished from the
literature in the years since Knuth's description (why he places
it in 1973 I don't know, my copy dates to 1968). Many more
recent sources consider reference counting simply
one form of garbage identification. The survey by Cohen
(Computing Surveys, 9/81), for instance, discusses reference counting
and marking as just two alternative ways of identifying garbage.
Gabriel (Performance and Evaluation of Lisp Systems) says of the
Xerox scheme, "Garbage collection is patterned after that
described by [Deutsch, 1976]. A reference count is maintained..."
Moon ("Garbage Collection in a Large Lisp System") discusses
reference counting alternatives under the name garbage collection.
Reference counting seems to have been accepted as a method of
preforming one sub-task of garbage collection; Hoey's nit-picking
is neither productive nor, since the Xerox approach is not pure
reference counting, accurate.
--
scott preece
gould/csd - urbana
uucp: ihnp4!uiucdcs!ccvaxa!preece
arpa: preece@gswd-vms
------------------------------
Date: Mon, 6 Oct 86 10:05 EDT
From: Scott Garren <garren@STONY-BROOK.SCRC.Symbolics.COM>
Subject: Garbage Collection
Relative to discussions of garbage collectors I would like to point out
that there are issues of scale involved. Many techniques that work
admirably on an address space limited to 8 Mbytes (Xerox hardware)
do not scale at all well to systems that support up to 1 Gbytes
(Symbolics).
Non-disclaimer: I am an employee of Symbolics and am of course
emotionally and financially involved in this issue.
------------------------------
Date: Mon, 6 Oct 86 15:39:20 EDT
From: ambar@EDDIE.MIT.EDU (Jean Marie Diaz)
Reply-to: ambar@mit-eddie.UUCP (Jean Marie Diaz)
Subject: Re: Xerox vs Symbolics -- Reference counts vs Garbage collection
In article <8609262352.AA10266@ai.wisc.edu> neves@ai.wisc.edu (David
M. Neves) writes:
>Do current Symbolics users use the garbage collector?
At MIT, yes. I do recall at Rutgers this summer that I was forever
doing a (gc-on), because some user there was turning it off....
--
AMBAR
"Timid entrant into the Rich Rosen School of Computer Learning...."
------------------------------
Date: Tue, 7 Oct 86 12:39:28 edt
From: "Timothy J. Horton" <tjhorton%ai.toronto.edu@CSNET-RELAY.ARPA>
Subject: Re: Xerox vs Symbolics -- Reference counts vs Garbage collection
> When I was using MIT Lisp Machines (soon to become Symbolics) years
> ago nobody used the garbage collector because it slowed down the
> machine and was somewhat buggy. Instead people operated for hours/days
> until they ran out of space and then rebooted the machine. The only
> time I turned on the garbage collector was to compute 10000 factorial.
> Do current Symbolics users use the garbage collector?
>
> "However, it is apparent that reference counters will never
> reclaim circular list structure."
>
> This is a common complaint about reference counters. However I don't
> believe there is very many circular data structures in real Lisp code.
> Has anyone looked into this? Has any Xerox user run out of space
> because of circular data structures in their environment?
>
> --
> David Neves, Computer Sciences Department, University of Wisconsin-Madison
> Usenet: {allegra,heurikon,ihnp4,seismo}!uwvax!neves
> Arpanet: neves@rsch.wisc.edu
In the Xerox environment at least, the extensive use of windows is one of
the most common sources of problems. Often is the case that a window must
be 'related' somehow to another window i.e. you create a subsidiary window
for some main window (as a scroll window is to a display window), and the
two windows must 'know' about each other. The obvious thing is to put
pointers on each window's property list to the other window, "et viola"
a circular list. Everything on the property lists of the two windows
also gets kept around, and since Xerox windows are such good places to
store things the circular structure is often very large. (check out the
stuff on a 'Sketch' window's property list)
A careful programmer can avoid such problems. In the case of windows, one
just has to be careful about how windows find out about one another (some
kind of global variable scheme or a directed search of all windows).
Yet accidents happen and windows can kill the environment fairly quickly.
Yes, I have lost an environment to just this problem (that's why I know),
and it's very hard to tell what happened after the fact.
------------------------------
Date: Fri 10 Oct 86 10:57:53-PDT
From: Keith Price <PRICE%GANELON@usc-oberon.ARPA>
Subject: Garbage collection
The experience in our lab is that there is no garbage collection
other than the Ephemeral GC; the "traditional" GC is never needed or
executed and programs are faster with the Ephemeral GC on than with it
off. I can't say whether it is "better" than Xerox or the new LMI GC,
but it is clear that "traditional" GC is a thing of the past for most
Lisp work stations already and comparisons to such old methods do not
contribute to the knowledge pool.
K. Price.
price%ganelon@usc-ecl
------------------------------
End of AIList Digest
********************
