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goal is to simulate specific outcomes explicitly involving C; even then,
the initial adjustment of the model would be significantly facilitated
if C is added to the system only after validating the two-node construct.
If the network is more complex, the attempt to reduce the number of
nodes might not be possible. For example, the construct shown in
Figure 10-26 (lower panel) cannot be transformed into a two-node model
because of the high system interconnectivity.
In closing, we note that significant theoretical complications arise
when networks have multiple steady states of different types. Methods
such as Boolean formalization, described in Thomas (1973; 1983),
could be used to analyze such systems. This method serves as an
intermediary analysis between modeling phases 2 and 3 described in the
first section of this chapter. The idea behind it is to describe complex
systems in simpler terms that allow for preliminary finding of all stable
and unstable steady states. Other complex endocrine networks with
intertwined feedback loops are considered in Farhy and Veldhuis
(2004; 2005), where their analysis strongly depends on the specific
physiology.
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