Introduction to program schemas with applications to program slicing.

Abstract;
A program schema defines a class of programs, all of which have identical 
statement structure, but whose functions and predicates may differ. 
A schema thus defines an entire class of programs according to how its 
symbols are interpreted.  A slice of a schema is obtained from a schema 
by deleting some of its statements. We show that the  static slicing problem 
defined using programs can be expressed as a corresponding problem defined 
using the semantics of schemas. In particular, Weiser's static slicing  algorithm, 
which uses only the data  and control dependence relations given by a program,  
is essentially defined on schemas. We show that  Weiser's algorithm does not 
always give minimal acceptable slices, and discuss conditions under which we 
have proved that it does compute a minimal  slice.