Vocabulary

A group of semantic resources (or terms) usually classified in alphabetical order, which are created within a specific conceptual frame and following a particular methodology. The semantic resources of a vocabulary are organised based on their relationships- hierarchically or not- forming a whole network of concepts

In the framework of Semantics.gr the term Vocabularies comprises the following types of resources:

• Thesauri: they are vocabularies of terms that may or may not describe a particular topic, they can be organised hierarchically in one or more levels, they can be related as synonyms, antonyms, etc and they can be classified alphabetically or conceptually (ie Getty AAT, LC relator terms, etc)
• Classifications and classification schemes: this type of vocabularies follow a strictly hierarchical order and present terms in thematic categories. Classification schemes often contain serial alphanumeric values (ie DDC, LCC)
• Authority files: list of standardised terms for person names, corporate bodies or concepts commonly used within a domain, ie by libraries and memory institutions for cataloguing purposes. They are mainly based on MARC documentation models. Some examples: VIAF, LCSH, MeSH

Semantic Resource

An informational resource that belongs to a Vocabulary and which represents or describes a concept, a timespan, a place a natural person or a corporate body. A semantic resource includes a persistent URI, a proposed namespace- sometimes in more than one languages- and a series of values that correspond to different attributes. A semantic resource is an instance of one or more classes and assigns values to the individual attributes.

Data Model

A group of classes, attributes and relationships that can be used to describe semantic resources in a particular knowledge domain. A data model can be defined as an ontology. In the framework of Semantics.gr, a Data Model is a group of classes and attributes that has been constituted based on the OWL ontology. A Data Model that is hosted in Semantics.gr might have first been established elsewhere, such as SKOS, MADS/RDF and EDM, or it may be an original model or an extension/adaptation/specialisation of an existing one (application profile)

Class

A class defines a group of semantic resources that share common attributes.

Property

It is used to declare a relationship between different semantic resources (class instances) or between informational resources and values

Triplete

Threefold statement that includes: a. the informational resource (subject), b.an attribute (predicate), and c. the value (object). The value can be a simple text or alphanumeric string, or another informational resource when a triplete describes the relationship between two informational resources. A triplete is the most concise form that an RDF graph can take, although the latter usually includes a quite large number of such statements.

Schema

It is an specialization of a Data Model that describes in detail the structure, the attributes and their value and relationship constraints. In essence, the Vocabulary Schema defines in detail the data entry/update form, through which, a user adds or manages individual semantic resources.

RDF (Resource Description Framework)

A model to construct informational resources on the Semantic Web. In RDF an informational resource is described by a group of tripletes.

Namespace

A group of URIs with a common prefix (e.g. dc, dcterms, skos, etc). A namespace defines the common space to reference an ontology or a data mode.

Uniform Resource Identifiers (URIs)

A W3C standard. It is a unique sequence of characters that identifies a logical or physical resource used by web technologies. It follows specific syntax rules. It points to an informational resource in a univocal way. The informational resource often contains more information about a particular specific or abstract entity.