NIELSEN@KL.SRI.COM (Norm R. Nielsen) (04/30/88)
Information Industries Divisional Seminar
Joshua: A System That Provides
Syntactically Uniform Access to Heterogeneously
Implemented Data Bases
Steve Anthony
Symbolics
May 11 at 10 AM, BS-208
Joshua is a system developed at Symbolics that provides
syntactically uniform access to heterogeneously implemented
knowledge bases. Its power comes from the observation that
there is a "protocol of inference" consisting of a small set
of abstract actions, each of which can be implemented in many
ways. The object-oriented programming facilities of Flavors
have been used to control the choice of implementation. Each
statement in the language represents an instance of a class
identified with that statement's predicate. Steps of the
protocol are implemented by methods inherited from the
classes. Since inheritance of protocol methods is a compile-
time operation, very fine-grained control can be achieved
with little run-time cost.
Joshua offers two major advantages. First, a Joshua
programmer can easily change his or her program to use more
efficient data structures without changing the rule set or
other knowledge-level structures. Second, it is easy to
build interfaces which incorporate existing tools into
Joshua, without having to modify those tools.
Steve Anthony will discuss the capabilities and design of
Joshua, followed by some demonstrations. We will be meeting
in the Intelligent System Laboratory's computer room so that
the demonstrations can be run live on the Symbolics 3670.
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