Database Server Models for WMS and WFS Geographic Web Services - Geographical Information Systems: Trends and Technologies - page 163

is induced by an environment (context) E, has a set of properties, T, a set
of structures, L, and a binary relationship, I, named incidence of E, such
as I ⊆ T x L.
Let L' ⊆ L, be a set of structures. The set of common properties to the
structures of L' is X = {x ∈ T | ∀ y ∈ L', (x, y) ∈ I}.
Let T' ⊆ T, be a set of properties. The set of structures with all the
properties in T' is Y = {y ∈ L | ∀ x ∈ T', (x,y) ∈ I }.
A concept is formally represented with a couple (X, Y). Let F be the set
of the concepts, relevant to an environment E. Let f 1 be (X 1 , Y 1 ) and f 2 be
(X 2 , Y 2 ) in F, f 1 is subsumed by f 2 (noted f 1 ≤ f 2 ) if X 1 ⊆ X 2 or from the dual
point of view Y 2 ⊆ Y 1 . (F, ≤) is a complete lattice, named lattice of concepts
linked to the formal environment E.
The lattice of concept we propose to use, references to a classifi cation
tool of the RL as an ontology of domain. This lattice describes concepts
involved in a specifi c domain in order to take into account the different
links between the components of this domain. Numerous works deal with
the modeling (in the ontology sense) such as (OGC 2008) with CityGML.
CityGML, recognized as a norm, provides a classifi cation for 3D modeling
of a town. Emgard and Zlatanova (2008) propose a generic meta-model for
a 3D representation as a complement to CityGML.
In comparison with these works, we propose a meta-base (instead
of a meta-model) with the formal representation of elements, rules and
constraints that regulate the creation of a database (but not the application
domain).
Within the lattice, a concept represents, from a semantic point of view,
the level of interpretation for a group of data. This level is relevant for a
specifi c user.
Let E = (T, L, I) be a formal context. T is a set of themes. L is a set of
Relevant Link (RL). I is an incident function of E such as I ⊆ T x L and (t, l)
∈ I, t ∈ T and l ∈ L. That means that theme “t” is a property of the Relevant
Link “l”.
Let t be a theme such as t ∈ T. The set of RL sharing this theme is L'
such as L' = {l ∈ L / (t, l) ∈ I}.
A formal concept is a theme shared by a set of RL. It is formally
represented by a couple (t, L') where t ∈ T and L' ⊆ L.
Extended Defi nition of Relevant Links
To provide a classifi cation of Relevant Links (RL), we propose to extend
the defi nition of a RL (given in the Data Conceptual Schema section).
Let N denote the set of natural integers. The extensions are: an identifi er
(i.e., id, such as id ∈ N), a theme (i.e., t ∈ T) and a complexity θ associated
with the process in charge of obtaining data. This complexity is data base
implementation dependent.