DIKRAN@SU-CSLI.ARPA (07/12/84)
From: Dikran Karagueuzian <DIKRAN@SU-CSLI.ARPA>
[Forwarded from the CSLI Newsletter by Laws@SRI-AI.]
EXPRESSIVENESS OF LANGUAGES
Jock Mackinlay, Stanford, will give a talk on ``Expressiveness of Language''
on Friday, July 13, at noon in Braun Lecture Hall, Seeley Mudd Chemistry
Bldg., as part of SIGLunch series. The talk is expected to last no more than
45 minutes.
ABSTRACT: A key step in the design of user interface is
the choice of a language for presenting facts to the user.
The spectrum of possible choices ranges from general
languages, such as predicate calculus, to more specialized
languages, such as maps, diagrams, and ad hoc languages.
General languages can express a broader range of facts than
more specialized languages, but specialized languages are
more parsimonious. The basic motivation for the research
described in this talk is to construct a presentation
system that can automatically choose an appropriate graphic
language for presenting information to a user.
This talk addresses two issues that must be considered when
choosing a language to represent or present a set of facts.
First, a language must be sufficiently expressive to state
all the facts. Secondly, it may have the property that
when some collections of facts are stated explicitly,
additional facts are stated implicitly. Such a language
should not be chosen if these additional facts are not
correct. We first define when a fact is stated in a
message. Using this definition, we define when a set of
facts is expressible in a language. This definition can
be used to determine whether a language should be chosen
to represent or present a set of facts. We also consider
the problem of choosing between languages that are
sufficiently expressible for a set of facts. Two criteria
are considered: the cost of constructing a message and the
cost of interpreting a message.