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		     B O S T O N   U N I V E R S I T Y

			Computer Science Department

			    C O L L O Q U I U M


		Interpretations of Objects and Object Types

			     Michele Bugliesi
			    University of Padua


			   Wednesday, October 21
				  3:00pm

			 (Coffee served at 2:45pm)

			  Seminar Room / MCS 135

The work on interpretations of object calculi is motivated by the desire to
give sound  and formal foundations  to object-oriented  languages and their
specific constructs and  techniques.  In most  of the existing work in this
area, interpretations are given in terms of  a reduction of object oriented
constructs and techniques to  procedural or functional programming.  In the
first part of  the talk, I  will survey the main  concepts and ideas behind
object  calculi and their type systems;  then I will describe existing work
on   interpretations,   from    Cook's  "generator model"      and  Kamin's
self-application semantics, to recent  work  by Bruce, Abadi and  Cardelli.
In the second part,  I will present  a new (sub)type preserving translation
of  a  calculus  of extensible objects   that  supports  method invocation,
functional   method   override,  and     extension  into   a    polymorphic
lambda-calculus with recursive types and  (higher-order) subtyping. The new
translation clarifies the nature of extensible objects as recursive records
that incorporate the basic functionalities  of classes and class  instances
in class-based object-oriented models.  It  also clarifies the relationship
between  the calculi of extensible and  non-extensible objects presented in
the recent literature.


Host: Prof. Assaf Kfoury (kfoury@cs.bu.edu)

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