Under-Determined System
All real metabolic systems fall into this category
Systems are moved into the other categories by measurement of fluxes and additional assumptions.
Infinite feasible flux distributions, however, they fall into a solution space defined by the convex polyhedral cone.
The actual flux distribution is determined by the cell's regulatory mechanisms.
It absence of kinetic information, we can estimate the metabolic flux distribution by postulating objective functions(Z) that underlie the cell’s behavior.
Within this framework, one can address questions related to the capabilities of metabolic networks to perform functions while constrained by stoichiometry, limited thermodynamic information (reversibility), and physicochemical constraints (ie. uptake rates)