Titolo: 
Coalgebraic Accounts of Objects and Classes

Autori:
Marina Lenisa, Furio Honsell


ABSTRACT.  
We discuss the co(bi)-algebraic description of objects and classes
proposed by H.Reichel and studied by B.Jacobs, H.Tews, et al., where
classes are represented by co(bi)-algebras and objects are elements of
the state space of the class.
We extend the coalgebraic approach to binary methods, i.e. methods
which take more than one instance of the hosting class as argument,
and we study the induced observational equivalence on
objects. Moreover, we generalize the approach, in order to capture
more advanced object oriented features, such as object
re-classification in Fickle.


Some references:

S. Drossopoulou, F. Damiani, M. Dezani-Ciancaglini, and
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ACM Transactions On Programming Languages and Systems, 24(2):153-191,
2002.

U. Hensel, M. Huisman, B. Jacobs, H. Tews, Reasoning about Classes in
Object-Oriented Languages: Logical Models
and Tools. In: Ch. Hankin (ed), European Symposium on
Programming, LNCS 1381, p.105-121, 1998.

B. Jacobs, Objects and classes, co-algebraically. In: B. Freitag,
C.B. Jones, C. Lengauer, and H.-J. Schek (eds) Object-Orientation with
Parallelism and Persistence Kluwer Acad. Publ., 1996, p. 83--103.

B. Jacobs, Invariants, Bisimulations and the Correctness of
Coalgebraic Refinements. In: M. Johnson (ed), Algebraic
Methodology and Software Technology, LNCS 1349, p.276-291, 1997.

H. Reichel, An approach to object semantics based on terminal
co-algebras, MSCS, 5:129-152, 1995.

H. Tews, Coalgebras for Binary Methods. CMCS'2000, ENTCS 33, 2000.