  Models are centrally important in many scientific fields. A model is a
representation of a selected part of the world, which is the model s target
system. Here, a system consists of a software portion as a component among many
others. Event-B is a modeling method for formalizing and developing systems
whose components can be modeled based on set theory and first-order logic. The
thinging machine (TM) is a diagram-based model establishes three levels of
representation: (1) a static structural description, which is constructed upon
the flow of things in five generic operations (activities; i.e., create,
process, release, transfer, and receive); (2) a dynamic representation, which
identifies hierarchies of events based on five generic events; and (3) a
behavioral representation according to the chronology of events. This paper is
an exercise in contrasting the formal Event-B to the diagrammatic TM. The
purpose is to further understand modeling in computer science. This is
motivated by the claim that computer scientists should not invent specific
languages to do the modeling. Important notions such as events and behavior are
contrasted, and a case study system of traffic on a bridge is modeled in
Event-B and TM. The results seem to indicate the need for both modeling
approaches.
