Between input and output: the process itself
Signals connect processes. Processes perform the transformational changes, deliver oxygen to our organs, digest, produce, convert money, buy and sell, form mixtures and compounds, influence plant, animal and human masses. At first, and indeed in the history of cognition often for thousands of years, processes look mysterious and can only be better understood through signals that can be detected only with certain methods and tools, and even in this case only through assumptions, targeted experiments and speculations. This is why we represent the first step of the approximation with a black box.
During the examination of the processes treated as black boxes and after the calculation of the input-output relationships, the models of systems receive a mathematical representation. These input-output relationships are expressed in mathematical functions which describe them as a mathematical model subject to properly tested and specified conditions.
Such conditions always mean simplification and the omission of some effects, so in system science it is important to consider and examine them similarly to the conceptual frameworks applied.
The resulting mathematical representations work in models as operators. The so-called operators specify how input signals are processed and transformed into output signals by the system.
These tools become effective in computer programmes developed on this basis for examining the system.