Extension:WikibaseLexeme/Data Model

This is a living document, describing the conceptual data model used by WikibaseLexeme. It is not a specification of any concrete binding, implementation, mapping, or serialization. The data model of WikibaseLexeme describes the structure of the data that is handled as "Lexemes" in Wikibase, such as words and phrases. While it would be theoretically possible to model these things using Items, a more expressive specialized model helps to reduce complexity, and improve re-use and mappings to other vocabularies.
 * Lexeme:
 * Lemma
 * Language
 * Lexical category
 * Statements
 * Forms:
 * Representation
 * Grammatical Features
 * Statements
 * Senses:
 * Gloss
 * Statements

This data model is conceptual ("Which information do we have to support?") and does not specify how this data should be represented technically ("Which data structures should the software use?") or syntactically ("How should the data be expressed in a file?"). Separate documents describe the serialization of the Wikibase data model in JSON and in RDF (Resource Description Framework).

The Lexeme data model defines basic concepts and relationships needed to describe lexemes, which act as a fixed ontology. This ontology provides a minimal scaffolding that allows Items and Statements to be used for detailed modeling of a lexeme.

The specification of the Lexeme data model is based on the Wikibase data model, so the Wikidata glossary and the Wikibase data model primer may be helpful in understanding this document. The Lexeme data model aims to align with the LEMON model by the Ontolex W3C community group, where useful and practical. However, in the spirit of Wikibase, the Lexeme model is designed to be simple and flexible enough for casual collaborative editing, as opposed to the more formalized approach taken by LEMON.

Lexeme
A Lexeme is a lexical element of a natural language, such as a word, a phrase, or a prefix (see Lexeme on Wikipedia). Lexemes are Entities in the sense of the Wikibase data model.

A Lexeme is described using the following information:


 * An ID. Lexemes have IDs starting with an "L" followed by a natural number in decimal notation, e.g. . These IDs are unique within the repository that manages the Lexeme.
 * A Lemma for use as a human readable representation of the lexeme, e.g. "run".
 * The  Language  to which the lexeme belongs. This is a reference to a concrete Item, e.g. Q1860 for English.
 * The Lexical category  to which the lexeme belongs. This is given as a reference to a concrete Item, e.g. Q34698 for adjective.
 * A list of Statements to describe properties of the lexeme that are not specific to a Form or Sense (e.g. derived from or grammatical gender or syntactic function)
 * A list of Forms, typically one for each relevant combination of grammatical features, such as 2nd person / singular / past tense.
 * A list of Senses, describing the different meanings of the lexeme (e.g. "financial institution" and "edge of a body of water" for the English noun bank).

Lemma
The lemma is a human readable representation of the lexeme (see Lemma on Wikipedia). Typically, the canonical form of the lexeme (e.g. the infinitive form of verbs) will be used as the lemma (see also lemon:canonicalForm).

Lemmas are not simple strings, but MultilingualTextValues, since the same lemma may have multiple spellings. This is specially important for languages that use multiple alphabets, such as Serbian.

Note: Lemmas are not unique, nor is the combination of Lemma, Language, and Lexical category. Two distinct lexemes with the same lexical category can exist in the same language if they have different morphology, that is, different forms.

Form
The morphology of the lexeme is understood as a set of Forms. Each form defines how a lexeme changes based on a specific syntactical role or mode it may take in a sentence (see also lemon:Form).

A Form is described using the following information:


 * A representation, spelling out the Form as a string.
 * A list of grammatical features that define for which syntactical role the given form applies. These are given as references to a concrete Items, e.g. Q814722 for participle.
 * A list of Statements further describing the Form or its relations to other Forms or Items (e.g. pronunciation audio, rhymes with, used until, used in region)

Representation
A form's representation is its written form, as used in a text (compare lemon:writtenRep). Just like Lemmas, Representation are not simple strings, but MultilingualTextValues, since the same form may have multiple spellings, possibly in multiple scripts.

Grammatical Feature
A form's grammatical features specify under which conditions or in which syntactic role that form is used (see lexinfo:morphosyntacticProperty and grammatical category on Wikipedia). Multiple grammatical features can be combined to express that a form shall be used when all these features apply. Grammatical features are represented as references to Items.

Sense
The senses of a lexeme are the different meanings which it may represent in a text. The senses are given as natural language definitions or glosses (compare intensional definitions on Wikipedia).

A sense is described using the following information:
 * A Gloss, defining the meaning of the Sense using natural language.
 * A list of Statements further describing the Sense and its relations to Senses and Items (e.g. translation, synonym, antonym, connotation, register, refers to concept).

Note that senses can be connected to Wikidata Items via an appropriate Statement (compare lemon:denotes and lemon:evokes). However, such a connection should not be interpreted as the lexeme actually representing the concept defined by the item (compare lemon:LexicalSense and lemon:LexicalConcept). In particular, if two lexemes have senses that refer to the same concept in this way, this does not imply that the two lexemes are synonyms.

Gloss
A sense's gloss gives a natural definition of the sense (see Gloss on Wikipedia and skos:definition). Similar to Lemmas, Glosses are not simple strings, but MultilingualTextValues. However, the the reason is not providing support for variants, but to allow the gloss to be given in entirely different languages. E.g. it would be quite useful for a German learning French to have a German gloss for a French word.