Prof. Frank S. de Boer

Abstract:

In this talk I introduce a new symbolic semantics for a class of recursive programs which feature dynamic creation and unbounded allocation of objects. The semantics is based on a symbolic representation of the program state in terms of equations to model the behavior of a program as a pushdown system with a finite set of control states and a finite stack alphabet.

Adding pointer fields gives rise to a Turing complete language. However, assuming the number of reachable objects in the visible heap is bounded in all the computations of a program with pointers, we show how to construct a program without pointers that simulates it. Consequently, in the context of bounded visible heaps, programs with pointers are no more expressive than programs without them.