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Superposition
- Structure program as set of "layers".
- Higher layer can use services of lower layers.
- Lower layer never calls higher layers.
- Example: application program and operating system.
- Superposition of programs.
- Underlying program (and variables).
- Transform program such that its properties are preserved.
- Transformed program has aditional properties.
- Transformation introduces superposed variables.
- Assignments to underlying variables remain unaffected.
Wolfgang.Schreiner@risc.uni-linz.ac.at
Id: unity3.tex,v 1.1 1996/04/19 12:29:22 schreine Exp schreine