Summary: State­level and value­level simulations
in data refinement
William Leal 1,2 , Anish Arora 1,3
Department of Computer and Information Science, The Ohio State University,
Columbus, Ohio, USA
Abstract
Simulations are a popular way to show data refinement. Simulations that have
been proposed are either state level, relating concrete to abstract states in a given
state space, or value level, relating individual concrete to abstract values and hence
holding for all state spaces. Value­level simulations are less complex and easier to
use, but the extent of their completeness has not been well studied. We show that
in fact known value­level simulations are in general incomplete but are complete
when operations are limited to a single argument.
Key words: Data refinement, program correctness, formal verification, components
0 Introduction
Suppose we have a program pgm(A) that uses the operations of a data type
A. We wish to substitute a more concrete data type C while guaranteeing that
the behavior of pgm(C) will not surprise us. In fact, we would like to know if
we can do this for all programs, not just a particular one, in which case we can
say that C refines A. What ``not surprised'' means varies from one author to

Source: Arora, Anish - Department of Computer Science and Engineering, Ohio State University

Collections: Computer Technologies and Information Sciences