Concept-Oriented Blog

Concept-oriented model is based on the following main principles:

1. Separation of physical and logical structures [duality]. In COM any elements is defined as a member of two separate structures which are referred to as physical and logical. The physical structure has a hierarchical form and describes how elements are represented and accessed. In particular, it determines the life-cycle of elements, how they are identified and where they are stored physically. Once an element has been created it cannot change its position in the physical structure. The logical structure has a multidimensional hierarchical form where each element has a number of parents and a number of children. Cycles are not permitted and there exist two special elements: the top and the bottom. A list of parents (superelements) is stored as properties of this element and hence it is possible to change them. According to this separation each element is a member of two sets: one is its physical parent while the other are its logical parents.

2. Priority of order of elements [order]. In COM it is of crucial importance how elements are ordered rather than how they are organized into sets. This means that the meaning of any element is determined by its relative position to other elements in the logical structure where it has a number of parents and children. The element itself without its neighbours is meaningless because its position in the physical structure has normally a primitive semantics. In contrast to set-based approaches, in COM elements are ordered and only after that the sets are derived (a set consists of all children of one parent).

3. Managing links rather than elements. Since semantics is determined by the order of elements, the primary concern of any concept-oriented database management system consists in managing this order. This means that the links among elements are more important than the elements themselves.

4. Syntax and semantics. In COM syntax is defined as constraints imposed on possible properties of items imposed by concepts where items are physical children of concepts. Specifically, if a concept has a number of parent concepts (superconcepts) then its items have a syntactic constraint. This constraint means that all items must have superitems from these superconcepts.