Loop Based Taxonomy for Digital Systems

The complexity of digital systems domain asks for a specific and more nuanced taxonomy than the simple taxonomy used for digital circuits (combinational vs. sequential circuits).
I proposed a loop based taxonomy for digital systems in a communication held at the Romanian Academy in 1980 (published as [Stefan '83a]).
The main starting ideas are: Because the number of the loops including each other determine the degree of autonomy in a digital system, it can be used to classify digital systems. The resulting taxonomy is:


[Stefan '83a] Gh. Stefan: "Structurari neechilibrate in sisteme de prelucrare a informatiei" (Unbalanced Structures in Information Processing Systems), in Inteligenta artificiala si robotica (Artificial Intelligence and Robotics), Ed. Academiei RSR, Bucuresti, 1983. p. 129 - 140.
[Stefan '83b] Gh. Stefan, I. Draghici, T. Muresan, E. Barbu: Circuite integrate digitale (Digitale Integrated Circuits), Ed. Didactica si pedagogica, Bucuresti, 1983.
[Stefan '91] Gh. Stefan,: Functie si structura in sistemele digitale (Function and Structure in Digital Systems), Ed. Academiei Romane, Bucuresti, 1991.
[Stefan '93] Gh. Stefan: Circuite integrate digitale (Digital Integrated Circuits), Ed. Denix, Bucuresti, 1993.
[Stefan '97] Gh. Stefan: Circuit Complexity, Recursion, Grammars and Information. Multiple Morphisms, Ed. Transilvania University of Brasov, 1997.
[Stefan '00] Gh. Stefan: Circuite si sisteme digitale, Ed. Tehnica, 2000.
[Stefan work in endless progress] Gh. Stefan: Loops & Complexity in Digital Systems. Lecture Notes on Digital Design in the Giga-Gate/Chip Era