A Study of the Schema Intension Graphs Model (SIG) Approach to the Relative Information Capacity (RIC) of Data Schemas

摘要

The notion of information capacity preserving was originated from the Relative Information Capacity (RIC) theory (Hull 1986). It is concerned with information preserving mapping, dominance and equivalence for simple conceptual data schemas and it is used as a correctness measure for schema transformation with no information loss. Four progressively less restrictive dominances were proposed. These dominances and equivalences are based on the existence of abstract functions between the instances of a pair of schemas. But it was not clear how to reason about the existence of such abstract functions, which are curial for RIC. Miller et al (1993, 1994) redefined the absolute and internal dominance among the four and put forward the Schema Intension Graph (SIG) data model with a view to enabling reasoning about the existence of abstract functions. The literature would seem to show that the RIC theory and the SIG model are widely accepted and used.