Use will be made of the Directed Acyclic Graph (DAG) description of algebraic functions throughout this work . The MINLP formulation is based on a balanced binary tree superstructure for the representation of the equations describing a physical model. The overall goal is to enable the assembly of free-form algebraic functions by connecting predictor variables and operators, such that the resulting function predicts the dependent variable values accurately. As an example, the structure with nodes in a four-layer balanced binary tree is shown in Figure . The formulation presented here is based on Ref , but follows a different concept in the setup of the binary tree in order to reduce the number of binary variables in the global optimization. These modifications are addressed in Section 2.2.