We are using cookies to give you the best experience on our site. Cookies are files stored in your browser and are used by most websites to help personalise your web experience.
A greater concept is specified as a type of this concept dimensions. Thus a concept has as many greater concepts as it has dimensions (fields).
This concept in this case is called a lesser concept. A concept has as many lesser concepts as it is used as a dimension type in other concepts.
For example, if concept
Person has a dimension of type
Address (where this person lives) then
Address is a greater concept while
Person is a lesser concept:
CONCEPT Address // Greater concept IDENTITY CHAR(3) addrId ENTITY CHAR(256) address CONCEPT Person // Lesser concept IDENTITY CHAR(3) persId ENTITY CHAR(256) name Address address // Points to a greater concept
Thus concept dimensions (fields) play a very important role in the concept-oriented model because they allow us to establish a partial order among concepts (and their instances as a consequence). This feature is unique for COM and distinguishes it from other models. It is precisely why we say that COM relies on the theory of ordered sets. In particular, this ordering is then used to define two main operations: projection and de-projection.
Let us assume that each employee (concept
Employee) belongs to one department (concept
Department) and each department has one manager (concept
CONCEPT Manager IDENTITY CHAR(8) managerId ENTITY ... CONCEPT Department IDENTITY CHAR(8) deptId ENTITY Manager manager // Points to greater concept CONCEPT Employee IDENTITY CHAR(8) empId ENTITY Department department // Points to greater concept
From this definition we see that concept
Employee is a lesser concept of concept
Department because it references it in its dimension
Department is a greater concept of concept
Employee but it is a lesser concept of concept
Manager because it references it in its dimension