Greater concept
From Wiki
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.
Example
Let us assume that each employee (concept Employee) belongs to one department (concept Department) and each department has one manager (concept Manager):
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. Concept Department is a greater concept of concept Employee but it is a lesser concept of concept Manager because it references it in its dimension manager.
