Erect means build or upright. If you erect a house, you build it. If you stand erect, you hold your body as tall as possible.
A mathematical model is a description of a system using mathematical concepts and language.The process of building a mathematical model is termed mathematical modeling.Mathematical models are used in the natural sciences (such as physics, biology, earth science, meteorology) and engineering disciplines (e.g. computer science, artificial intelligence). mathematical model is a description of a system using mathematical concepts and language.
The model in MVVM is an implementation of the application's domain model that includes a data model along with business and validation logic. Examples of model objects include repositories, business objects, data transfer objects (DTOs), Plain Old CLR Objects (POCOs), and generated entity and proxy objects.