Izvorni znanstveni članak
Problems in the Application of Generalized Abstractions
Mile Pavlić
; Informatics Dept., Pedagogical Faculty, University of Rijeka, Rijeka, Croatia
Sažetak
According to the methodology for planning an information system, the basic concept used in describing complex systems is the principle of abstraction. This paper analyzes a generalized abstraction which is often a natural description of the system. A problematic variant of a generalized tree is defined in which the following are valid: a great number of subtypes exist, the number of subtypes is unknown as well as the attributes of known and unknown subtypes. The paper sets out the problems and gives one solution by substituting any generalized abstraction with the model made with the help of a series of classificatory and aggregative abstractions. The paper shows that one coordinate of the modeling space which is assumed to be basic and orthogonal in the modeling space can be carried out through complex relations between the other two referential coordinates, in other words, classification and aggregation are two extreme variants (coordinates) of modeling the system and generalization is a defined function in the given coordinates. Besides making a theoretical contribution, the paper also contributes in a practical manner, because in the implementation of problematic variants of generalization it gives an overall solution to the model without loss of information.
Ključne riječi
generalization; problematic generalization; methodology; abstraction; aggregation; classification; E-R model; relational model
Hrčak ID:
78992
URI
Datum izdavanja:
14.6.1996.
Posjeta: 597 *