POSTDATA CORE ontology
The POSTDATA Network of Ontologies enables the standardization of European Poetry by defining models that represent several concepts across different literary traditions, periods, poetic genres and authors. This enables the integration and exchange of poetry data as Linked Data among traditions and facilitates the retrieval of different aspects of Poetic Works, which helps to carry out relevant research in Comparative Literature and Comparative Metrical Studies in a quantitative fashion.
The core ontology of the network described hereafter (postdata-core) focuses on general and bibliographical characteristics of poems, plays and songs. It also defines classes that are not specific to the domain of poetry but are required to provide a complete description of poetic works, such as Persons, Organisations, Events and Places, while other features of the poetic works like prosodic, rhetorical devices, or textual transmission aspects are represented in the rest of ontologies of the network.
The core-ontology must be imported by the rest of ontologies in the network. For this reason, besides containing the mentioned classes, it also provides a set of common properties that have the same semantics in all the classes in which they are defined. In this way, it is possible to express semantics in an unambiguous way for properties that from this point of view conceptually represent the same.
The objective of this ontology is to provide the necessary knowledge for the poetic works and its manifestations representation.
It is important to note that some classes are alienated with the edm ontology.
The most relevant classes of POSTDATA core ontology are:
The pdcore:PoeticWork class, that represents an abstract concept of an artistic creation. In POSTDATA these creations must be in verse (poem, play, song). General data properties representing title, language, keyword, subtitles (if any), literary tradition, function (if any) or theme are included to instances of Poetic Work. For example: Os Lusíadas by Luis Vaz de Camões; La Commedia by Dante; the poem Ad te deus by an Anonymous author written in between the 7th and 9th centuries. This class is in turn aligned with the edm ontology as a edm:ProvidedCHO specialization and also with FRBRoo ontology as a frbroo:F1 specialization. The following diagram shows the data properties and object properties having class Poetic Work as range:
The previous diagram shows the datatype properties (inside the class’ box) and object properties (labeled arrows, possibly including inverse property name after “/”) that are relevant for this class. As we can see, a Poetic Work is related to their creator or creators (CreatorRole) and several Redactions that are physical realisations of the work at hand. We can also specify a geographic location related to the provenance of the work and we could also find depicted characters (Role). In addition, we make use of several SKOS schemes to represent the possible values for the poetic type and genre of the work, as well as to express the educational level of the author. Finally, we can express different dates associated with the poem using imported classes from postdata-dates ontology.
The pdcore:Redaction class, that covers Poetic Work manifestations. It refers to a concrete version or instantiation of the Poetic Work. For example, one Poetic Work can have different editions; each edition represents one Redaction and they all refer to the same Poetic Work. As such, the textual elements as well as other aspects like the type of edition, witnesses used and not used, layout, explicit, incipit, or audience must be expressed using instances of Redaction. For example: The palaeographic edition of A solis ortu usque ad occidua preserved in Lat. 1154 (BNF) and its critical edition are two Redaction of the same Poetic Work. This class is a specialization of the class frbroo:F22. Find below the context diagram for the class Redaction:
As we can see from the previous diagram, Redaction includes the data and object properties used to describe the textual elements of a work. To do so, we can make use of data properties like incipit or text. We can also make use of object properties to represent textual elements (TextUnit and OrderedTextUnitList) that can be further described employing POSTDATA Structural Elements ontology (stanzas, lines, words).
The pdcore:Ensemble class, that is an abstract work that contains more than one Poetic Work. An Ensemble might be conceived as a collection of works, organized by author, by book song, by book of poems; or as a work mainly written in prose that contains more than one poetic pieces (each one of them being its own Poetic Work). In case a prose book contains various poems, each poem constitutes one Poetic Work; at the same time, all poems contained in the prose book are part of the same Ensemble. We describe instances of this class through some properties like the total number of lines, poems and plays. Eg: Les fleurs du mal. This class is a frbroo:F17 specialization. The following diagram represents relevant properties available to describe instances of type Ensemble:
As we can see, Ensembles have some Poetic Works that are part of it and can have a specific creator associated (CreatorRole). An Ensemble can also be related with provenance Place and can be referenced in a specific location of the text.
This ontology also models necessary classes to cover aspects regarding authorship, associated agents, places of origin and related events. We describe hereafter these classes including information about reused classes from other ontologies/vocabularies:
The pdcore:Person class and the pdcore:Organisation class, which are hierarchically dependent on the Agent class, as they share many functionalities. They are foaf:Person specialization and a foaf:Organisation specialization, respectively.
We have a set of properties that can be used to express biographical data about a Person, including Places of birth and death. We also make use of several SKOS schemes to control the possible values of other personal data. As we can see, a Person may belong to an Organisation. It and may have an assocaited Role, or be directly associated to a Redaction as editor. In addition, we can express that a Person takes a special function in a Redaction (dedications, mentions, characters) or an Event in which is involved.
Organisations are formed by Persons. They can be associated to a Place, or it could be and Agent involved in an Event. Organisations, like Persons, can also have an associated Role and be mentioned in a Redaction.
The previous figure shows that a Place can be described using latitude and longitude. It also may be mentioned in a Redaction and could be an element of an Event.
Events may have some of its actor elements defined (Places and Agents). An Event can be mentioned in a Redaction.
In the ontology, there are also two important classes, the pdcore:Role class and pdcore:Creator Role class, a Role specialization .
pdcore:Role is used to represent the role of the agents related to Poetic Work, its manifestations, its transmissions and other elements.
pdcore:Creator Role is used for represent the function of a person or organization in the creation of a poetic work, redaction or other transmission element. This class also covers anonymous authorships and incorrect attributions.
As we can see from the previous diagram, Roles are specific functions of Agents regarding a Poetic Work, Redaction or Ensemble. When the Role plays the function of creator, we make use of CreatorRole class, which includes an attribute (data property) to express that the author attribution has been agreed to be wrong. A SKOS scheme can be used to express other functions.
Also in the core there are properties of habitual use in different classes of the ontology because their semantics are the same for all of them. Many of these properties were defined through the properties reuse that belong to the following vocabularies dc and dcterms, and to schema , for example, dc:title, schema:url or others like pdcore:commentary
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