We present a new formalism called GAMMA in which programs are described as multiset transformers. We show the relevance of this formalism with respect to program development by proposing a systematic program derivation method and illustrating it with several nontrivial problems (sorting, shortest path, longest upsequence). © 1990.
Banâtre, J. P., & Le Métayer, D. (1990). The gamma model and its discipline of programming. Science of Computer Programming, 15(1), 55–77. https://doi.org/10.1016/0167-6423(90)90044-E