Data Dependencies and Program Slicing: from Syntax to Abstract Semantics

We discuss the relation between program slicing and data depen-dencies. We claim that slicing can be defined, and therefore cal-culated, parametrically on the chosen notion of dependency, which implies a different result when building the program dependency graph. In this framework, it is possible to choose dependency in the syntactic or semantic sense, thus leading to compute possibly dif-ferent, smaller slices. Moreover, the notion of abstract dependency, based on properties instead of exact data values, is investigated in its theoretical meaning. Constructive ideas are given to compute abstract dependencies on expressions, and to transform properties in order to rule out some dependencies. The application of these ideas to information flow is also discussed