In natural language processing, linguistics, and neighboring fields, Linguistic Linked Open Data (LLOD) describes a method and an interdisciplinary community concerned with creating, sharing, and (re-)using language resources in accordance with Linked Data principles. The Linguistic Linked Open Data Cloud was conceived and is being maintained by the Open Linguistics Working Group (OWLG) of the Open Knowledge Foundation, but has been a point of focal activity for several W3C community groups, research projects, and infrastructure efforts since then.

Definition and Development

LLOD Cloud (2016-05-24)
LLOD Cloud (2016-05-24)

Linguistic Linked Open Data describes the publication of data for linguistics and natural language processing using the following principles:[1]

The primary benefits of LLOD have been identified as:[2]

The home of the LLOD cloud diagram is under linguistic-lod.org[3]

LLOD vocabularies

Aside from gathering metadata and generating the LLOD cloud diagram, the LLOD community is driving the development of community standards with respect to vocabularies, metadata and best practice recommendations.

According to the state-of-the-art overview by Cimiano et al. (2020),[4] these include:

As of mid-2020, most of these community standards are actively worked on. Particularly problematic is the existence of multiple incompatible standards for linguistic annotations, and in early 2020, the W3C Community Group Linked Data for Language Technology has begun to work towards a consolidation of these (and other) vocabularies for linguistic annotations on the web.[15]

Community

The LLOD cloud diagram has been developed and is maintained by the Open Linguistics Working Group (OWLG) of the Open Knowledge Foundation (since 2014 Open Knowledge), an open and interdisciplinary of experts in language resources.

The OWLG organizes community events and coordinates LLOD developments and facilitates interdisciplinary communication between and among LLOD contributors and users.

Several W3C Business and Community Groups focus on specialized aspects of LLOD:

LLOD development is driven forward by and documented in a series of international workshops, datathons, and associated publications. Among others, these include

Applications of LLOD

Linguistic Linked Open Data is applied to address a number of scientific research problems:

Linguistic Linked Open Data is closely related with the development of

Selected research projects

Uses and development of LLOD have been subject to several large-scale research projects, including

Selected resources

As of October 2018, the 10 most frequently linked resources in the LLOD diagram are (in order of the number of linked datasets):

Aspects

There are a number of recurring discussions regarding the different aspects of the term, its applicability and for a particular type of resources.[32]

Linguistic Data: Scope and Classification

See also: Language resource

Aside from resources used in and created for linguistic research, the LLOD cloud diagram also includes ontologies, terminologies and general knowledge bases whose development was not originally driven by interest in language sciences or language technology, e.g., the DBpedia. As a criterion for inclusion into the LLOD diagram, the OWLG requires "linguistic relevance": "[A] dataset is linguistically relevant if it provides or describes language data that can be used for the purpose of linguistic research or natural language processing."[33] This does include linguistic resources in a strict sense ("condition 1": an annotated or otherwise structured resource created for application in language sciences or language technology, as demonstrated, for example, by a scientific publication at a linguistics-related journal or conference), but also resources "that can be used for annotating, enriching, retrieving or classifying language resources ... [if their relevance] can be verified by the existence of links between a resource (whose linguistic relevance is to be confirmed) and resources fulfilling condition (1)" ("condition 2").[34]

A related issue is the classification of linguistically relevant datasets (or language resources in general). The OWLG developed the following classification for the LLOD cloud diagram:[35]

Note that in this classification, term bases are at the fringes of linguistic relevance, as these are normally created for purposes other than language technology or linguistic research.

Open Data: Availability

See also: Open data

LLOD is defined in relation to Linked Open Data, and LLOD resources (data) should thus conform to licenses in accordance with the Open Definition.[36] For generating the LLOD cloud diagram (and the LOD diagram), this does, however, not seem to be enforced yet, so that the technical criterion is availability over the web and a metadata entry. In the OWLG, it has been repeatedly discussed whether non-commercial (academic) resources could be included with a general consensus of admitting them for the moment (2015) but subsequently enforcing stricter requirements along with the growth of the LLOD cloud. As of January 2018, it was not agreed upon yet when this move was about to happen.[37] As of January 2020, machine-readable license metadata was available for 86 LLOD resources, of these, 82 adopted open licenses, 4 adopted non-commercial licenses.[38]

In a broader sense, the term LLOD technology (infrastructures, tools, vocabularies) can also used to refer to the technology independently from whether actually open resources are involved, e.g., in the name of the EU project Pret-a-LLOD that features several commercial business cases.[39] This is justified for applications that consume (rather than provide) open data, but moreover, also when linked data technology and the adoptation of other LLOD conventions (esp., the use of RDF vocabularies developed in the context of LLOD) are applied in order to facilitates the seamless integration of LLOD resources (open resources).

The abbreviation "LLOD" can be used to refer to either LLOD technology (use of Linked Data and LLOD vocabularies, independent from the legal status of the data being processed) and LLOD resources (open data). For disambiguation, the terms "LLOD resources" and "LLOD technology" can be used. For emphasizing application or applicability to non-open resources, also "LLD" (Linguistic Linked Data) has been used.[40] A possible compromise is the acronym "LL(O)D" for the technology. A "Licensed Linguistic Linked Data" cloud that contains non-open resources does currently (June 2020) not exist.[38]

Linked Data: Formats

See also: Linked data

The definition of Linked Data requires the application of RDF or related standards. This includes the W3C recommendations SPARQL, Turtle, JSON-LD, RDF-XML, RDFa, etc. In language technology and the language sciences, however, other formalisms are currently more popular, and the inclusion of such data into the LLOD cloud diagram has been occasionally requested.[32] For several such languages, W3C-standardized wrapping mechanisms exist (e.g., for XML, CSV or relational databases, see Knowledge extraction#Extraction from structured sources to RDF), and such data can be integrated under the condition that the corresponding mapping is provided along with the source data.

Selected literature

An exhaustive description on the state of the art on LLOD is provided by

The concept of a Linguistic Linked Open Data cloud has been originally introduced by

The first book on the topic is

According to Cimiano et al. (2020),[41] other seminal publications since then include

Developments from 2015 to 2019 are summarized in the collected volume by

References

  1. ^ a b Open Linguistics Working Group. "Linguistic LOD". linguistic-lod.org. LIDER project. Retrieved 2016-05-24.
  2. ^ Chiarcos, Christian; McCrae, John; Cimiano, Philipp; Fellbaum, Christiane (2013). Towards open data for linguistics: Lexical Linked Data (PDF). Heidelberg: In: Alessandro Oltramari, Piek Vossen, Lu Qin, and Eduard Hovy (eds.), New Trends of Research in Ontologies and Lexical Resources. Springer. Retrieved 2016-05-24.
  3. ^ "Linguistic Linked Open Data. Information about the current status of the growing cloud of linguistic linked open data". Retrieved 10 December 2019.
  4. ^ Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. ISBN 978-3-030-30224-5.
  5. ^ "Lexicon Model for Ontologies: Community Report, 10 May 2016". www.w3.org. Retrieved 2020-06-05.
  6. ^ "Deliverables of W3C's Web Annotation Working Group". w3c.github.io. Retrieved 2020-06-05.
  7. ^ Hellmann, Sebastian; Lehmann, Jens; Auer, Sören; Brümmer, Martin (2013). Alani, Harith; Kagal, Lalana; Fokoue, Achille; Groth, Paul; Biemann, Chris; Parreira, Josiane Xavier; Aroyo, Lora; Noy, Natasha; Welty, Chris (eds.). "Integrating NLP Using Linked Data". The Semantic Web – ISWC 2013. Lecture Notes in Computer Science. Berlin, Heidelberg: Springer. 7908: 98–113. doi:10.1007/978-3-642-41338-4_7. ISBN 978-3-642-41338-4.
  8. ^ Chiarcos, Christian; Fäth, Christian (2017). Gracia, Jorge; Bond, Francis; McCrae, John P.; Buitelaar, Paul; Chiarcos, Christian; Hellmann, Sebastian (eds.). "CoNLL-RDF: Linked Corpora Done in an NLP-Friendly Way". Language, Data, and Knowledge. Lecture Notes in Computer Science. Cham: Springer International Publishing. 10318: 74–88. doi:10.1007/978-3-319-59888-8_6. ISBN 978-3-319-59888-8.
  9. ^ Chiarcos, Christian (2012). Simperl, Elena; Cimiano, Philipp; Polleres, Axel; Corcho, Oscar; Presutti, Valentina (eds.). "POWLA: Modeling Linguistic Corpora in OWL/DL". The Semantic Web: Research and Applications. Lecture Notes in Computer Science. Berlin, Heidelberg: Springer. 7295: 225–239. doi:10.1007/978-3-642-30284-8_22. ISBN 978-3-642-30284-8.
  10. ^ Chiarcos, Christian; Sukhareva, Maria (2015-01-01). "OLiA – Ontologies of Linguistic Annotation". Semantic Web. 6 (4): 379–386. doi:10.3233/SW-140167. ISSN 1570-0844.
  11. ^ Cimiano, P.; Buitelaar, P.; McCrae, J.; Sintek, M. (2011-03-01). "LexInfo: A declarative model for the lexicon-ontology interface". Journal of Web Semantics. 9 (1): 29–51. doi:10.1016/j.websem.2010.11.001. ISSN 1570-8268.
  12. ^ de Melo, Gerard (2015-01-01). "Lexvo.org: Language-related information for the Linguistic Linked Data cloud". Semantic Web. 6 (4): 393–400. doi:10.3233/SW-150171. ISSN 1570-0844.
  13. ^ "Data Catalog Vocabulary (DCAT) - Version 2". www.w3.org. Retrieved 2020-06-05.
  14. ^ McCrae, John P.; Labropoulou, Penny; Gracia, Jorge; Villegas, Marta; Rodríguez-Doncel, Víctor; Cimiano, Philipp (2015). Gandon, Fabien; Guéret, Christophe; Villata, Serena; Breslin, John; Faron-Zucker, Catherine; Zimmermann, Antoine (eds.). "One Ontology to Bind Them All: The META-SHARE OWL Ontology for the Interoperability of Linguistic Datasets on the Web". The Semantic Web: ESWC 2015 Satellite Events. Lecture Notes in Computer Science. Cham: Springer International Publishing. 9341: 271–282. doi:10.1007/978-3-319-25639-9_42. ISBN 978-3-319-25639-9.
  15. ^ ld4lt/linguistic-annotation, ld4lt, 2020-05-19, retrieved 2020-06-05
  16. ^ "Best Practices for Multilingual Linked Open Data Community Group". Retrieved 9 December 2019.
  17. ^ "Linked Data for Language Technology Community Group". Retrieved 9 December 2019.
  18. ^ Bird, Steven; Liberman, Mark. "Towards a formal framework for linguistic annotations" (PDF). In: Proceedings of the International Conference on Spoken Language Processing, Sydney, 1998. Retrieved 2016-05-25.[permanent dead link]
  19. ^ ISO 24612:2012. "Language resource management -- Linguistic annotation framework (LAF)". ISO. Retrieved 2016-05-25.
  20. ^ Eckart, Richard (2008). Choosing an XML database for linguistically annotated corpora. SDV. Sprache und Datenverarbeitung 32.1/2008: International Journal for Language Data Processing, Workshop Datenbanktechnologien für hypermediale linguistische Anwendungen (KONVENS 2008), Universitätsverlag Rhein-Ruhr, Berlin, Sep 2008. pp. 7–22.
  21. ^ Chiarcos, Christian. "Interoperability of Corpora and Annotations (draft version)" (PDF). In: Christian Chiarcos, Sebastian Nordhoff, and Sebastian Hellmann (eds.) Linked Data in Linguistics. Representing and Connecting Language Data and Language Metadata, 2012. Retrieved 2016-05-25.
  22. ^ "lod2.okfn.org (archived version)". Archived from the original on 7 March 2014. Retrieved 9 December 2019.
  23. ^ "Multilingual Ontologies for Networked Knowledge (Monnet)". European Commission, CORDIS EU research results. Retrieved 10 December 2019.
  24. ^ "LIDER: Linked Data as an enabler of cross-media and multilingual content analytics for enterprises across Europe". European Commission, CORDIS EU research results. Retrieved 10 December 2019.
  25. ^ "Quality Translation by Deep Language Engineering Approaches". European Commission, CORDIS EU research results. Retrieved 10 December 2019.
  26. ^ "Linked Open Dictionaries (LiODi)". Retrieved 10 December 2019.
  27. ^ "Open Framework of E-Services for Multilingual and Semantic Enrichment of Digital Content". Retrieved 10 December 2019.
  28. ^ "POSTDATA – Poetry Standardization and Linked Open Data". Retrieved 10 December 2019.
  29. ^ "Linking Latin. Building a Knowledge Base of Linguistic Resources for Latin". Retrieved 10 December 2019.
  30. ^ "Pret-a-LLOD project home page". Retrieved 10 December 2019. "Pret-a-LLOD". European Commission, CORDIS EU research results. Retrieved 10 December 2019.
  31. ^ "CA18209 - European network for Web-centred linguistic data science". cost. European Cooperation in Science and Technology. Retrieved 10 December 2019.
  32. ^ a b For a history of these discussions, see the Open Linguistics mailing list archives, available only as a backup under https://github.com/open-linguistics/linguistics.okfn.org/tree/master/backup
  33. ^ Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. p. 33. ISBN 978-3-030-30224-5.
  34. ^ Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. pp. 33–34. ISBN 978-3-030-30224-5.
  35. ^ Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. pp. 36f. ISBN 978-3-030-30224-5.
  36. ^ Chiarcos, Christian and Pareja-Lora, Antonio (2020), Open Data—Linked Data—Linked Open Data—Linguistic Linked Open Data (LLOD): A General Introduction. In: Pareja-Lora, Antonio; Lust, Barbara; Blume, Maria; Chiarcos, Christian (eds.). Development of Linguistic Linked Open Data Resources for Collaborative Data-Intensive Research in the Language Sciences. The MIT Press, p.1-18.
  37. ^ "linguistics.okfn.org/003004.html at master · open-linguistics/linguistics.okfn.org · GitHub". Retrieved 2020-06-05.
  38. ^ a b Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. p. 37. ISBN 978-3-030-30224-5.
  39. ^ "Prêt-à-LLOD – Prêt-à-LLOD project website". Retrieved 2020-06-05.
  40. ^ See the title of the book by Cimiano, Chiarcos, Gracia, McCrae (2020). However, the acronym LLD (June 2020: 7 unambiguous Google scholar matches) seems to be rarely used in comparison to LLOD (June 2020: 309 unambiguous Google scholar matches).
  41. ^ Cimiano, Philipp; Chiarcos, Christian; McCrae, John P.; Gracia, Jorge (2020). Linguistic Linked Data: Representation, Generation and Applications. Springer International Publishing. pp. vi. ISBN 978-3-030-30224-5.