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LEXICALAReview 29 ❘ July 2021

Evoke: A Web application for thesauri

and Linguistic Linked Data

Sander Stolk

Introduction

The manner in which information is shared has changed rapidly

with the advent of the Web. New forms for sharing lexical data have

emerged, too, owing to the transition from ink to Internet. A notable

one is Linguistic Linked Data (LLD), which offers several benefits

over other formats by taking advantage of decentralized Internet

technology and open Web standards. The benefits in using this form

– and in applying related Web technologies – are demonstrated in the

new Web application Evoke. Evoke allows exploring and interacting

with linguistic resources, employing a novel method that enables

users to view a thesaurus, extend it – without the risk of infringing on

licenses or requiring additional hosting costs with publishers – and

perform new and exciting analyses over a combination of datasets.

Moreover, the application showcases how a number of mechanisms,

built on top of LLD, can be employed to reduce barriers for users to

start working with valuable linguistic resources. The development of

Evoke has been supported by experts in lexicography, linguistics and

philology (amongst other fields), to ensure the software is intuitive

and useful for both research and educational purposes. The following

sections will discuss (1) the Web application Evoke; (2) A Thesaurus

of Old English, the first LLD resource made available in Evoke; and

(3) current uses in research and education of these two resources.

(1) Evoke

The Web application Evoke allows users to interact with thesauri.

These lexicographic works organize words according to meaning –

by means of a semantic hierarchy – rather than alphabetically, thus

enabling the user to move from meaning to words that express that

meaning. Users of Evoke can not only browse and view content

captured within these linguistic resources (cf. Figures 1 and 2), but

also expand on them and, owing to the organization principle of

such works, perform analyses through the semantic lens of their

overarching hierarchies. The resulting onomasiological profiles that

are generated by Evoke are based on features of interest that the user

selects: specific labels, languages, and/or parts of speech. A generated

profile contains statistics and charts on the item count of a selection,

its degree of ambiguity (indicating polysemy), its degree of synonymy,

Sander Stolk is a PhD

researcher in Digital

Humanities at Leiden

University. He holds an

MSc in Computer Science

from VU Amsterdam

and an MA in English

Language and Culture

from Leiden University.

His research investigates

how the dissemination

and reuse of thesauri can

be improved by utilizing

Linked Data technology,

having the analysis of

information needs of

scholars and development

of the Web application

Evoke at its core, and he

is a member of the W3C

OntoLex community

that works on standards

regarding Linguistic

Linked Data. He is also

Head of Innovation at

Semmtech, a company

specializing in using

Linked Data technology.

s.s.stolk@hum.leidenuniv.nl

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LEXICALAReview 29 ❘ July 2021

its distribution over categories in the hierarchy (cf. Figure 3), and a

distribution over the depth of the semantic hierarchy (indicating how

specific in meaning the selected words are, cf. Figure 4).

Through the functionality of Evoke, users can explore the lexis in a

thesaurus, and optionally also in other datasets, with ease and powered

by the decentralized mechanisms offered by LLD methodologies (cf.

Cimiano et al. 2020). A notable feature of LLD is the use of so-called

URIs as data identifiers (that is, using Web addresses to identify

words, word senses, labels, and concepts in the semantic hierarchy),

which allow one to reference data elements and link additional

content. This approach can be likened to how Web pages employ

links. Instead of linking Webpages, however, Evoke and its use of

LLD enable users to link data. Although use of the Evoke interface

is not mandatory for creating such links, users can use it to add

information easily by annotating content.

Annotating a specific word, for instance, can be achieved in Evoke by

typing a sentence with a label (indicated by a hashtag). Doing so will

automatically create a piece of Linked Data annotation that adheres

to the Web Annotation standard of W3C (see #riddle47 in Figure

Evoke is available at

http://evoke.ullet.net.

A demonstration of its

functionalities can be

found at http://evoke.

ullet.net/demo.

Figure 1. Navigating the

semantic hierarchy of A

Thesaurus of Old English

in Evoke

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LEXICALAReview 29 ❘ July 2021

5; cf. Sanderson et al. 2017). The novelty here is that annotations

created in Evoke are not stored in a database but are instead stored

locally in the user’s browser. The annotations can be downloaded

as a file for backup, and backups can be reactivated in the browser.

The publisher of the original content therefore does not need to host

these annotations. Moreover, the annotations themselves only contain

references to the identifiers, or URIs, of the original content without

including that content in the annotation itself. As alluded to before,

this methodology can entice users to explore a lexicographic work and

interact with it, formulate a plan of research, and only at a later stage

take the hurdle in activating an account and getting support for further

research – be it in the form of a more open license or in getting access

to advanced services from the publisher of the resource.

(2) A Thesaurus of Old English: An LLD resource

The first lexicographic resource made available in Evoke as LLD is A

Thesaurus of Old English (Stolk 2019). This thesaurus captures lexis

of Old English, the early medieval variant of English spoken between

roughly 500 and 1100 AD. Upon its first publication in 1995, this

resource has been met with high praise, having been called “the most

Figure 2. A list of Old

English words that denote

“the voice”

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LEXICALAReview 29 ❘ July 2021

important contribution to Old English studies for years”, since the

“comprehensive analysis” that it forms allows scholars to “investigate

what distinctions Anglo-Saxons felt important enough to make in the

lexicon” (Görlach 1998). The value of lexicographic works such as

this is evident, then, for the audience which they target. As pointed

out, dictionaries and thesauri allow one to explore not just language

but also culture. They offer a lens through which users can learn many

details on words in a given vocabulary, including (but not limited to)

nuances in meaning, part of speech, and restrictions in regional or

temporal use.

Many scholars who have used or reviewed A Thesaurus of Old

English have indicated their wish to include additional information,

such as indications of region, etymology, metaphorical use, and so

on (e.g. Dance 1997, Bremmer 2002, Anderson et al. 2016). Given

the fact that lexicographers cannot cater to every research need, this

calls for extendibility of the dataset. That is to say, researchers (and

other users) would benefit from the means to add data, form new

queries over the combined information, and visualize the connections

to acquire new insights. Indeed, the team behind the lexicographic

Figure 3. Chart in Evoke

on the distribution of Old

English word senses over

categories in the semantic

hierarchy; a selection of

senses found in the text

Exeter Riddle 47 (orange)

are compared to all known

ones (blue).

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LEXICALAReview 29 ❘ July 2021

resource itself could benefit from such engagement with their work,

too, being able to accumulate feedback, incorporate more data,

and offer services based on their innate knowledge of the structure

of the lexicon that is at the heart of the research being done. Such

extendibility constitutes the precise functionality of Evoke that was

demonstrated to be of great value in both research and educational

use, as will be discussed in the next section.

(3) Exploring Early Medieval English Eloquence

To assess the usefulness of Evoke both in research and for education,

a research project was formulated with the title Exploring Early

Medieval English Eloquence. Based on the case study of a single

thesaurus, this project has brought together 17 scholars from

universities and lexicographic institutions from across Europe to

explore the contents of A Thesaurus of Old English using Evoke.

The various aspects of research approach the information from

the perspective of a specific discipline, namely that of linguistics,

literary-criticism, history, lexicography, and philology. In their

explorations, the researchers (and in educational settings, their

students) set about viewing other material next to that of A Thesaurus

Figure 4. Chart in Evoke

on the distribution of Old

English word senses over

the depth of the semantic

hierarchy; a selection of

senses found in the text

Exeter Riddle 47 (orange)

are compared to all known

ones (blue).

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LEXICALAReview 29 ❘ July 2021

of Old English, some by linking an already existing source and others

by using the annotation system in Evoke.

Novel research done within this project include analyses of lexis

used in specific texts (e.g. Beowulf) or used by specific authors

(e.g. Ælfric). Their analyses offer us new insights into the semantic

choices made by authors or present in genres. Such onomasiological

profiles may act as semantic fingerprints in identifying authorship

or in positioning other work. Other research focuses on metaphors

associated with anger and their development through the history of the

language. Lastly, various researchers work on linking Old Frisian and

Old Dutch lexis with the semantic hierarchy of the thesaurus. This will

allow us to contrast how many nuances these language communities

respectively had, next to those of Old English, in expressing certain

concepts such as kinship or greetings. All these researchers have

linked up additional information to the original thesaurus content.

Results have been presented at the 21st International Conference of

English Historical Linguistics (ICEHL21, Leiden University) and will

Figure 5. Information on

one of the senses of the

Old English word þeof

[thief] in Evoke, including

an annotation from the

dataset “riddle47” that

marks this specific sense.

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LEXICALAReview 29 ❘ July 2021

be published in a special issue of the journal Amsterdamer Beiträge

zur älteren Germanistik, entitled Exploring Early Medieval English

Eloquence, to be published in open access in fall 2021.

As regards the usefulness of thesauri in education, in the past two

years students at Leiden University and the University of Groningen

have used Evoke and A Thesaurus of Old English to explore aspects

of Old English language and culture. Dr. Kees Dekker presented

his experience on the use of Evoke as part of an introductory course

on Old English at the University of Groningen; students at Leiden

University participate in a 2-hour workshop that familiarizes them

with digital tools and resources for studying Old English (A Thesaurus

of Old English, Evoke, and the Dictionary of Old English and its

Corpus). Workshop materials, created by Dr. Thijs Porck and Sander

Stolk, are available on request. The learning exercises created at both

universities will be incorporated in the Evoke website. Courtesy of

Prof. Carole Hough (University of Glasgow), these will include units

from Learning with the online Thesaurus of Old English. The resulting

online material is due to be made public in fall this year.

References

Anderson, W., E. Bramwell and C. Hough (eds.). 2016. Mapping

English Metaphor through Time. Oxford: Oxford University Press.

A Thesaurus of Old English. http://oldenglishthesaurus.arts.gla.ac.uk.

Bremmer Jr, R.H. 2002. Treasure Digging in the Old English

Lexicon. NOWELE 40, 109–14.

Cimiano, P., Chiarcos, C, McCrae, J.P. and J. Gracia. 2020.

Linguistic Linked Data: Representation, Generation and

Applications. Heidelberg: Springer.

https://www.springer.com/gp/book/9783030302245.

Dance, R. 1997. Review of A Thesaurus of Old English. Medium

Ævum 66:2, 312–13.

Dictionary of Old English. https://www.doe.utoronto.ca/.

Görlach, M. 1998. Review of A Thesaurus of Old English. Anglia

116:3, 398-401.

Hough, C. and C. Kay. (eds.). 2017. Learning with the online

Thesaurus of Old English. https://oldenglishteaching.arts.gla.ac.uk/

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Sanderson, R., Ciccarese, P. and B. Young (eds.). 2017. Web

Annotation Data Model: W3C Recommendation 23 February

2017. https://www.w3.org/TR/annotation-model/.

Stolk, S. 2019. A Thesaurus of Old English as Linguistic Linked Data:

Using OntoLex, SKOS and lemon-tree to Bring Topical Thesauri

to the Semantic Web. In Proceedings of the eLex 2019 conference,

2019. 223–247.

https://elex.link/elex2019/wp-content/uploads/2019/09/

eLex_2019_13.pdf.