Database Reference
In-Depth Information
data. Finally, we detail our semantic annotation
process which allows the CONTA local database
to be enriched with Web data.
name of the relation and its signature. For example,
the relation ContaminationRange represents the
average level of contamination of a food product
by a contaminant for a given number of samples.
This relation has for domain the symbolic types
FoodProduct, Contaminant and Samples Total
Number and for range the numeric type Contami-
nation Level. Figure 2 shows the structure of an
excerpt of the CONTA ontology.
This ontology has been expressed in OWL
distinguishing two types of knowledge: (i) generic
knowledge which define the structure of the ontol-
ogy: for instance, the class numericalType (resp.
the class Relation) which is the superclass of all
numerical types (resp. relations); (ii) domain-
dependant knowledge: for instance, the class
ContaminationRange is a subclass of the class
Relation and the class ContaminationLevel is a
subclass of the class numericalType.
The Structure of the CONTA Ontology
The CONTA ontology is composed of datatypes
-numeric types and symbolic types- and of rela-
tions that allow one to link datatypes.
Numeric types are used to define the numeric
data.A numeric type is described by the name of the
type, the units in which data of this type is usually
expressed, and the interval of possible values for
this type. For example, the type Contamination
Level can be expressed in the units µg/g, µg/kg,
ng/g, µg/l and has a range of [0, 1000].
Symbolic types are used when the data of
interest are represented as a string. A symbolic
type is described by the name of the type and the
type hierarchy (which is the set of possible values
for the type, partially ordered by the subsump-
tion relation). For example, FoodProduct and
Contaminant are symbolic types.
Relations are used to represent semantic links
between datatypes. A relation is described by the
Example 1
Figure 2 gives an excerpt of the CONTA ontol-
ogy.
Figure 2. A simplified excerpt of the CONTA ontology
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