Addressable approximations to nonaddressable data graphs

摘要

A data graph is obtained from a data structure by masking out the specific data items at nodes of the structure and concentrating only on linkages in the structure. Concerning structural uniformities of data graph, A. L. Rosenberg has proved that addressable data graphs can be implemented by “relative addressing.” But arbitrarily given data graphs do not always have such uniformities. Thus, the principal aim of this paper is to find some tools for approximating those graphs with no uniformities by addressable ones. Here, we adopt the notion of onto-homomorphism to formulate the approximation problem of data graphs and conduct a partially ordered set theoretic approach to the problem. The investigations reveal a necessary and sufficient condition on which an arbitrarily given data graph can be approximated by some “addressable” one.