Following is a summary from readings of a book that I consider important.
· A model is any incomplete representation of reality, an abstraction
· Models could be mathematical(quantitative), physical, mental, or a qualitative. Nonetheless, the essence is the question/s that the model can reliably answer for us.
· Sample of modeling languages developed as part of the IDEF family
o IDEF0-Focus is a functional or process model of a system
o IDEF1- Focus is an informational model of the information needed to support the functions of a system
o IDEF1X- Focus is a semantic data model using relational theory and an entity-relationship modeling technique
o IDEF2- Focus is a dynamic model of the system
o IDEF3- focus is both process and object state transition model of a system
· 3 types of questions:
o Descriptive: most commonly used in science and engineering. A descriptive model attempts to predict answers to questions which the truth may or may not be obtained in the future. Descriptive models are measured by the power or richness, understandability to both wide and narrow audiences, and precision with which they can be used to define the relative entity.
o Normative: can not be tested but are judged on their understandability and appeal across deciplines they can be used. Either it’s logical, or it should be refuted logically.
o Definitive: how should a concept be defined.
· Most effective process for developing and using a model is to begin by defining the questions the model should be able to answer.
· Models should be developed, tested, and refined.
· System validity addresses whether we have built the right system.
· IDEF0 Page Hierarchy
o A-0: Context or system function diagram ( contains A0)
o A0 : Level 0 diagram with first tier functions specified