On Characteristics of Information System Homomorphisms
The notion of information system homomorphism as a powerful tool to study the relation between two information systems was introduced by J.W. Grzymala-Busse. In this work, we will present some characteristics of information system homomorphism, which reveal the interdependence of the three mappings, namely, object mapping, attribute mapping and value domain mapping. Besides, given a partition on universe, we can derive a new information system homomorphism defining a partition on universe identical with the partition given. In the mean time, some invariant characteristics of upper approximation and lower approximation under information system homomorphism are investigated. At last, we establish a surjection between rough sets of information systems under an information system homomorphism.
information system homomorphism upper approximation lower approximation rough set