Abstract Versus Concrete Models¶
A mathematical model can be defined using symbols that represent data values. For example, the following equations represent a linear program (LP) to find optimal values for the vector \(x\) with parameters \(n\) and \(b\), and parameter vectors \(a\) and \(c\):
As a convenience, we use the symbol \(\forall\) to mean “for all” or “for each.”
We call this an abstract or symbolic mathematical model since it
relies on unspecified parameter values. Data values can be used to
specify a model instance. The
AbstractModel class provides a
context for defining and initializing abstract optimization models in
Pyomo when the data values will be supplied at the time a solution is to
In many contexts, a mathematical model can and should be directly defined with the data values supplied at the time of the model definition. We call these concrete mathematical models. For example, the following LP model is a concrete instance of the previous abstract model:
ConcreteModel class is used to define concrete optimization
models in Pyomo.
Python programmers will probably prefer to write concrete models, while users of some other algebraic modeling languages may tend to prefer to write abstract models. The choice is largely a matter of taste; some applications may be a little more straightforward using one or the other.