Newsgroups: rec.arts.int-fiction
Path: gmd.de!ira.uka.de!sol.ctr.columbia.edu!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!mcdchg!chinet!jorn
From: jorn@chinet.chi.il.us (Jorn Barger)
Subject: "Was: barger@ils" Ch 1 (CD &c)
Message-ID: <C0s0Ds.EMs@chinet.chi.il.us>
Organization: Chinet - Public Access UNIX
Date: Wed, 13 Jan 1993 04:56:14 GMT
Lines: 87

====================================================================
                        "Was: Barger@ILS"
                   (memoirs of an a.i. hacker)
                          by Jorn Barger

                     Chapter 1: CD Notation
====================================================================

(Okay, lissen up.  I find that the only way I ever get anything written is
if I treat it like journalism, with an always-imminent deadline.  So I'm
gonna stake out a little corner of this newsgroup to write a popular text
on AI, Schankian-style, based on my experiences working for the last three
years as a programmer at Schank's Institute for the Learning Sciences of
Northwestern University.  Let me know if you find these things useful,
because if I don't get any response I may stop trying.)

(My personal interest all along has been interactive fiction, but the
projects I worked on at ILS attacked more-general problems of CBR and
hypertext.  I expect you'll find my improvisations easier to follow if you
make printouts, because I'll typically realize, too late, where I've tied
some thought into a hopeless pretzel.  But, practicing what Schank
preaches, I'll try to just tell this as a story...)

I didn't really hear about Roger Schank until 1987, from a student of his,
Kris Hammond, who had just been hired by the CS department of the
University of Chicago.  I phoned Kris out of the blue after hearing him on
the radio talking about his planner "CHEF", wanting to ask him about
planning within videogames.  He referred me to Schank and Abelson's
"Scripts, Plans, Goals and Understanding" (locally pronounced spuh-GOO). 
It's definitely my personal favorite among Roger's books, because it
wrestles unapologetically with the absurdly difficult question of whether
a small finite set of symbols can represent the full breadth of human
experience.

I was dreaming of a videogame that went beyond the take-drop-use-fight
cliches of adventure games.  Schank's "CD notation" offers a set of verbs
that may be boiled down to:

give-take-make-move thing
give-take-make idea
insert thing into thing (ingest, but also enter)
extract thing from thing (expel, or exit)

These are inarguably *general*, but somewhere in the generalization
process all the interesting story content got bleached out: an 'insert'
into a body may be food or drugs or poison or penis or semen or scalpel or
Jarvik heart or shiv or bullet or midget-sub... and even *ideas* might be
seen as insertions into the head...

So in '87 Hammond turned me on to S&A's SPG&U.  And I was delighted,
because everything I'd been sampling on the bookstore shelves, AI-wise,
seemed just depressingly unconnected to my practical goals.  One tiny
exception, in an anthology on 'the Frame Problem', was a synopsis of the
"histories approach" to that problem:  in modelling the world, you can
reduce the amount of background detail you have to keep track of, if you
can analyse out a finite set of *qualitatively distinct life-histories*
that the system can embody.  Eg, a charged particle aimed towards a small
target may be:  a) refracted, b) reflected, c) absorbed, or d) transmitted-
without-change.  Each of these stories has an infinite range of
mathematically distinct instances, which can be described to any
ridiculous degree of detail/precision, but the most useful, practical,
tractable, compact summary of any particle-interaction is just to classify
it, in two bits, as one of these four 'histories'.

So who's compiling the catalog of human histories?  What's it look like,
already?  For interactive fiction, you want to know, eg, when an elf meets
an orc, what different ways might the meeting go?  Fight, communicate,
gift, theft, etc etc etc... but who knows what shape an exhaustive
inventory of such histories, broad enough to support true interactive
*literature*, will take?

As regards *planning*, I got the sense from Hammond that not a whole lot
of progress had been made since the 1960's game-tree-exhaustive-
combinatorial-search approaches.  Hammond called his "CHEF" a case-based
planner, effectively a 'histories' approach to planning:  pick an old plan
from the set of known plans and twiddle its variables until they fit the
current task.  But he admitted that CHEF's successes were *real* limited.

And then after a couple of visits Kris got too busy to go further, and I
wandered off on my own path (compiling a histories-based analysis of
romantic love, actually!) until in 1989 I heard that Schank was moving
from Yale to Northwestern, and mailed him my application for employment...

[Coming up next: Andrew Ortony's analysis of emotions]

Jorn Barger  jorn@chinet.chi.il.us   (was: barger@ils.nwu.edu)

