Abstract interpretation [3, 8] is a theory of sound approximation of mathematical structures, in particular those involved in the description of the behavior of computer systems. It allows the systematic derivation of sound methods and algorithms for approximating undecidable or highly complex problems in various areas of computer science (semantics, verification and proof, modelchecking, static analysis, program transformation and optimization, typing, software steganography, etc.). Its main current application is on the safety and security of complex hardware and software computer systems.