Abstract
The study of complex systems, although an interdisciplinary endeavor, it is considered as an integrating part of
physical sciences. Contrary to the historical fact that the eld is already mature, it still lacks a clear and unambiguous denition
of its main object of study. Here, I propose a denition of complex systems based on the conceptual clarications made by
Edgar Morin about the bidirectional non-separability of parts and whole produced by the nature of interactions. The concept
to which I arrived here is clear, not circular, neither too cryptic nor to explicit, and does not include any accompanying features
of the own system dened. It allows, as shown in the paper, to derive some of the main properties that such systems must have
as well as to propose its mathematical formalization.