=Paper= {{Paper |id=Vol-1899/CfWNs_2017_proc8-paper_8 |storemode=property |title=The Concept of Lexical Platform |pdfUrl=https://ceur-ws.org/Vol-1899/CfWNs_2017_proc8-paper_8.pdf |volume=Vol-1899 |authors= Maciej Piasecki,Tomasz Walkowiak,Ewa Rudnicka,Tomasz Naskręt,Francis Bond |dblpUrl=https://dblp.org/rec/conf/ldk/PiaseckiWRNB17 }} ==The Concept of Lexical Platform== https://ceur-ws.org/Vol-1899/CfWNs_2017_proc8-paper_8.pdf
                           The Concept of Lexical Platform

                              Maciej Piasecki1, Tomasz Walkowiak,1
                          Ewa Rudnicka,1 Tomasz Naskręt,1 Francis Bond2
    1
        G4.19 Research Group, Wrocław University of Science and Technology, Wrocław, Poland
                         {maciej.piasecki,tomasz.walkowiak,
                      ewa.rudnicka,tomasz.naskret}@pwr.edu.pl
            2
                Computational Linguistics Lab, Nanyang Technological University, Singapore
                                           bond@ieee.org



            Abstract. The paper presents an idea of Lexical Platform proposed as a means
            for a lightweight integration of various lexical resources into one complex
            (from the perspective of non-technical users). All LRs will be represented as
            software web components implementing a minimal set of predefined
            programming interfaces providing functionality for querying and generating
            simple common presentation format. A common data format for the resources
            will not be required. Users will be able to search, browse and navigate via
            resources on the basis of anchor elements of a limited set of types. Lexical
            resources linked to the platform via components will preserve their identity.

            Keywords: lexical resources, wordnet, interoperability of lexical resources.


1         The need for the integration of lexical resources
Lexical resources (LRs) have recently become more numerous for many languages.
They describe different aspects of their lexical systems. However, their impact on
popular, commercial and even research applications is surprisingly limited. One
reason for this is the fact that existing LRs often originate from a variety of research
projects, are based on different models and are encoded in different formats. All these
factors make combining them into one complex system a challenging task. From the
point of view of text processing applications, there seems to be no other way than
mapping all resources to one common model and a limited number of formats in order
to be able to identify links between individual resources or even to augment them
with appropriate links.
Non-technical users of LRs, interested in consulting and browsing them, also face
challenges in accessing them. LRs are spread across the web. Even if different LRs
can be found in some virtual catalogues like CLARIN VLO,1 every individual LR
usually has to be accessed separately via different dedicated browsing and searching
systems. Still, for such uses, we need only limited knowledge about a LR: what kind
of elements we can ask for and how to present the query and search results to the
users.

1
    https://www.clarin.eu/content/virtual-language-observatory-vlo
Our goal is to present an idea of a lexical platform as a virtual place for aggregating
different type of LRs as separate individual components in a way that they form an
interconnected system, a complex LR, from the user’s point of view. We assume that
the descriptions provided for LRs must be minimal and no common format should be
required to make the construction of the platform feasible. The platform should be
open for all types of LRs, but wordnets are in the focus since they are usually very
large resources, providing rich descriptions, but are not so easily accessible for many
users.


2      Related works
There are three main problems in linking LRs of different types: no common format
(even for wordnets), different models (also for wordnets) and, different solutions for
technical aspects of storing, accessing and linking the data within LRs. The first two
problems require different interpretations from the point of view of applications.

2.1      Formats and standards
One common format for LRs could solve most of the problems. Several standards
have been proposed but none of them gained overwhelming coverage.
Implementations of RDF for wordnets were proposed, but used only for single
wordnets, e.g. Princeton WordNet (PWN) ([8]) and DanNet ([16]). Several
implementations of Lexical Markup Framework (LMF), a generic ISO standard, have
been proposed for wordnets, e.g. KYOTO LMF ([22]), GermaNet LMF ([10]), UBY
LMF ([9]). However, KYOTO LMF is concentrated only on the representation of
synsets, and the other two also do not allow for full representation of all existing
wordnets, e.g. many features of plWordNet related to lexical units ([12]).
    Lemon (13]) has been proposed as an ontology-based representation for lexicons
and machine-readable dictionaries and linking them to the Semantic Web and the
Linked Data cloud. The Lemon-based representation is still very much focused on
PWN and cannot represent many elements present in different wordnets, but its
various applications have already shown its potential as a candidate for the future
`common format’. The main obstacle for the existing formats is the lack of effective
means for expanding them with new elements of the data format in a way which does
hamper existing applications.
    In human-oriented lexicography lexicons are mostly encoded as a tree, a
hierarchical data structure of parent-child relations ([15]). Many authors ([1], [11],
[15]) propose to use graph representation.

2.2      Platforms
UBY LMF2 platform ([7]) was built as a solution for integrating LRs on both
structural and semantic level. 12 LRs3 have been linked into a complex system.

2
    https://dkpro.github.io/dkpro-uby/
3
    https://www.ukp.tu-darmstadt.de/data/lexical-resources/uby/
However, all these LRs have been converted to one common implementation of LFM.
There is only one type of anchoring elements that are word senses.
     CILI that is Collaborative Interlingual Index is described as “a flat list of
concepts” which is currently based on PWN 3.0 set of synsets ([23]). It is intended to
serve as an intermediary between wordnets of different languages within the Open
Multilingual WordNet (OMW) ([4]). Currently, there are plans to extend CILI with
concepts lexicalised in languages other than English. CILI will require consistency in
the understanding of lexical and semantic relations among different languages. There
will be persistent identifiers for CILI entries. Concepts will never be deleted, only
deprecated or superceded. Candidates for new ILI concepts must be linked to a
concept in its ‘mother’ wordnet by one of well-known relations (hypernymy,
meronymy, antonymy) and indirectly linked via this concept to the already existing
CILI concept. CILI is available on open licence.
     OMW4 is an open platform aggregating wordnets of different languages linked
via PWN 3.0 ([5]). Its component wordnets share a common representation format,
i.e. currently CILI LMF format. For many wordnets the conversion to CILI LMF is
unidirectional, i.e. it is not possible to reconstruct the original structure of a wordnet
due to the flattening of the relation structure and the impossibility to reconstruct it.
     PANACEA5 ([3]) is a FP7 project focused on building a system of language
resources (enhanced with a handful of tools) for Machine Translation. Wide range of
resource for several languages have been developed and integrated, but LMF standard
was chosen as the data format for dictionaries6.
     LEAP (Lexical Engine and Platform)7 is a commercial product, focused on
multilingual dictionary data, semantically linked combined with asymmetrical
translation     memory.        It    offers    a    REST       API      for    developers.
Léacslann ([14]) is a platform for working with sets of lexical entries of arbitrary
structures. A collection of entries, called stocks, can be monolingual, bilingual,
terminology database, a collection of proverbs or a set of references to other
resources.
     Lexonomy8 (a descendant of the Léacslann) is a tool aimed for writing and
publishing dictionaries. An entry includes mainly: a lemma (a headword form), PoS,
word sense defined by a simple textual description and sense usage examples. Each
entry description can be a mixture of text and marked elements (inline XML markup)
corresponding to different elements of the entry structure. The dictionary has a
structure of graph ([15]).




4
   http://compling.hss.ntu.edu.sg/omw/
5
   http://www.panacea-lr.eu/
6
   http://www.panacea-lr.eu/system/deliverables/PANACEA_D3.4.pdf
7
   https://www.oxforddictionaries.com/our-story/leap
8
  http://www.lexonomy.eu/_info/
3    Basic Assumptions

The idea of the Lexical Platform (LexP) originated from a handful of observations
and intuitions.
     LexP should group together different LRs as independent components,
implemented as software modules. Only a minimal set of requirements should be
imposed on developers. Moreover, individual identity of all LRs must be visible and
preserved inside the platform. Crucially, LexP is not supposed to become a ‘super-
resource’, because that may cause reluctance of resource creators to join in.
     LexP will promote the use of a limited set of common formats, but it will not
enforce any specific data format on its components. A component may be located in
any freely selected network location. It does not need to be copied to LexP altogether
with the LR data. This can be an interesting option from the point of view of IPR
issues and data protection. A component will be accessible via a set of Programming
Interfaces (PIs). They can be implemented, e.g. as traditional Web Services (WSs).
One PI can be implemented as a one separate WS, or several PIs can be provided by a
single WS - this is a matter of a detailed design decisions for LexP. Still, some
minimal set of PIs will be specified and required to be implemented by every
component (including PIs that allow the user to obtain the description of a
component, access an element of the resource or get the visual representation of a
resource element). However, components can provide any number of additional PIs.
     LexP would not allow for any changes in the content of individual resources, as
well as in the links between them. LexP is meant only to be a tool for accessing a
complex system of linked resources, not a system supporting development of LRs.
     The access to the data from the component lexical resources will be constrained
in order to make the LexP construction feasible. LexP components will encapsulate
the data, i.e. the only access to the data will be possible only via the PIs of the
components. Every component can provide data in any format, but some formats, e.g.
Lemon (or its expansions), may be suggested as common ones. Construction of
converters from native formats to a limited number of common ones will be
promoted. Every component will be required to support addressing elements of LexP
via anchoring elements of limited and predefined types that will be specified by an
ontology. Still every LexP-complaint component can offer expanded methods of
addressing LR elements.
     Inter-linking of LRs via LexP components is a key issue. It will be based
exclusively on the content of LRs. Each component recognises references to elements
of the limited set of types. Such elements serve as selected points by which the data
from different components are anchored to the whole platform and inter-linked
between them. Such selected data elements will be called anchor elements. Anchor
elements should naturally originate from the construction of a LR. They should be its
characteristic elements which users browse it by or which users most usually search
for. Anchor elements should be also those data elements that provide native (or
natural, typical) mapping to other LR (or knowledge resources). The selection of
anchor element types can be left to resource creators, but if an anchor element is to be
used by other resources of the same type the way of naming it must be known to the
creators of those resources. The following types of anchor elements are expected to be
provided by different components, (a provisional list to be worked out in detail during
the design process): word form (or word, including multi-word expressions), lemma
(or literals, canonical forms, entry form, basic form), lexical unit (word sense), synset,
frame (syntactic and/or semantic), domain (context), and concept. Every component
will provide on request (via a PI) a list of anchor element types that it can recognise.
An ontology of anchor element types will be created (if possible based on an existing
one) and maintained as the only central knowledge resource of LexP, but this
ontology should be limited.
     The primary functionality of LexP will be focused on non-technological users and
will be close to the idea of Federated Content Search9 of CLARIN: the ability to
search from one single point across many corpora, but with a limited query language.
Users will be able at least
     ● to learn about existing LRs and the range of information provided by them,
     ● to search across combined LRs on the basis of anchor elements supported by
          different components and to browse LRs by lists of anchor elements
          retrieved from the components,
     ● to manually browse across linked LRs on the basis of names of anchor
          elements,
     ● and finally, to find out how to obtain and download original resources and to
          learn how to browse different LRs in their native browsers.
     In order to make manual browsing of different LRs from LexP, it is assumed that
all components are required to provide a PI generating a specified presentation format
for a specified anchor element. The generated presentation should highlight anchor
elements and user’s clicks on the anchor elements should be reported together with
the anchor element’s name to LexP in order to enable interactive browsing. The exact
presentation format is a matter of design decisions, but it should be as simple and as
popular as possible (in order to simplify the construction of components), e.g. HTML,
XML; SVG, etc.
     Users should be also able to list anchor elements described by a component and
the whole LexP. For this purpose, we need PIs that allow listing together with some
forms of filtering, e.g. PoS, UPOS, language, supertype (for ontologies), hypernym
(for lexico-semantic networks), semantic domains etc. Lists retrieved from
components will be collected by LexP and presented to the users as merged lists.
     It would be hard to follow versions of individual LR elements, so LR versions
will be reported by the description PI of a component.
     In the case of technological users, the support provided by LexP will be naturally
limited without the guaranteed mapping to a common format, but still some functions
can be envisaged. LexP can be used for collecting data sub-structures describing
specified anchor elements in a native format or some other format if a converter is
available. PIs for calculating similarity measures between anchor elements can be
envisaged. Other possible functions could provide, e.g., some statistics, clustering of
elements, mapping texts onto substructures extracted from LexP components.




9
    https://www.clarin.eu/content/content-search
4     Platform architecture

4.1    Lexical microservices
LexP will link diversified LRS in a flexible and autonomous way, i.e. the resources
linked will not be merged in one big `super-resource’, but each resource will be
preserved as a separate module and will keep its identity. Such a strategy should help
to convince a large group of resource creators for linking their resources to the
platform.
     The existing API for LRs are developed in different languages (Java, C++,
Python). Moreover, many of them (e.g. plWordNet [12], Walenty [18]) stores very
large data sets. Therefore, the time of loading such a component is much longer than
processing a single task. The solution is to run a LR component as a service with data
loaded into memory. Each service is running its own process. The usage of services
communicating with others by lightweight mechanisms solves also a problem of
variety of technologies used by LR components since there is no need for tight
integration. It results in a set of “cohesive, independent processes interacting via
messages” [6]. Microservices [21] and a service-oriented architecture [3] have
recently started gaining wide popularity. The microservice architecture will enable
continuous development/deployment [19] of LexP.
     Each LR will be represented inside the platform as a separate microservice.
Access to any LR requires some time, therefore it is worth to run several instances of
microservices for a given LR component. A queuing system will be used to distribute
requests among microservices. Each LR component will be assigned its own queue.
LexP microservice will collect tasks from a given queue and send back messages
when results are available. Such a solution will facilitate effective scalability
capabilities since a queuing system acts as a load balancer.
     Every LexP component implemented as a microservice will provide a set of
required PIs. A minimal set of required (obligatory) PIs will encompass functions:
     ● description - delivers meta-data for the resource and the component
          (including license information) and information about the PIs provided by
          the component, facilitates component registration in LexP,
     ● getElement - returns all descriptions related to a specified resource anchor
          element in their native format, e.g. description of all synsets for a given
          lemma in a wordnet,
     ● getHtml - generates a simple visualisation of a specified resource anchor
          element in HTML that can be easily rendered in web browser without the
          need of interpretation of the data,
     ● list - returns a list of anchor elements, several ways of filtering are
          envisaged.
The list could be extended for the specific needs of a LR, e.g. functions such as the
following (depending on the licence of the resource):
     ● getResource - returns a URL/URLs to the zipped resource (with data in a
          resource specific format/formats).
4.2      System architecture
The planned LexP architecture is presented in Fig. 2. We propose to use the AMQP10
protocol for lightweight communication with lexical microservices and the open
source RabbitMQ11 broker for a queuing system. AMQP protocol has clients for a
large number of different software platforms as required by technologies used by LR
PIs. In the proposed architecture, the additional server grants the access from Internet.
It works as a proxy for the core system delivering synchronous HTTP-based REST
API. Such an approach allows for easy integration with almost any kind of
applications including JavaScript. For applications oriented on asynchronous
processing the AMQP based access will be granted.
     It is assumed, that all data (requests, responses) will be sent in JSON format. In
the case that a given LR is not able to serialize a resource into JSON, results in other
formats (for example XML) will be encapsulated in JSON strings.




                         Fig. 1. Lexical Platform architecture

     In addition, a LexP orchestrator is planned to be developed. It is meant to process
all incoming requests to the platform. No external application will have a direct
access to any lexical microservice. The orchestrator is aimed to:
     ● filter all wrong requests,
     ● add mapping between an external resource name and an internal
         microservice name,
     ● send simple requests to a given type of a microservice (lexical resource),
     ● process complicated tasks (built on a sequence of calls to the lexical

10
     https://www.amqp.org
11
      https://www.rabbitmq.com
         resources, such as):
              ○ results for a list of anchor elements,
              ○ results for all types of resources for a single element,
              ○ selected combination of resources or their parts in the form of a
                   graph;
     ● process other tasks, for example:
              ○ listing of available resource types,
              ○ conversion of output formats,
              ○ providing access to the whole resource in a given resource specific
                   format,
              ○ logging of external tasks and users’ data (IP, user names) for
                   platform usage analysis;
     ● add prioritisation of tasks:
              ○ for example a simple task will be performed faster than a request for
                   a huge set of elements.
    The platform’s microservices can be deployed on the central server of LexP or on
servers of their suppliers (or authors, owners, etc.). If the external microservice is not
able to follow AMQP protocol, a specific, resource oriented adapter (see. Fig. 2) can
be developed to connect any external resource to the platform. A resource adapter can
include a cache capabilities to speed up the resource access.
    The proposed architecture includes also a service registry. It plays a role of a
simple database of microservices names. Microservice instances on the startup
registers itself in the given queue and deregistered on shutdown. Moreover, the
RabbitMQ broker may invoke a microservice health check to verify that an instance is
able to handle requests (if not the instance is removed from a list of the queue
consumers). The service registry monitors the number of clients of each queue and
provides a list of working components.
    The RabbitMQ is able to work in the distributed way. Several instances of
RabbitMQ could cooperate in different manners12 (with clustering, with federation,
and using the shovel). Therefore, it will be easy to distribute LexP among different
data centres.




12
     https://www.rabbitmq.com/distributed.html
  Fig. 2 An illustration of the working of Lexical Platform, within which modules
making available specific resources provide a presentation widget (here for simplicity
                   called HTML) for an element chosen by the user
4.3      Central web application
The architecture described in the previous chapter is oriented toward access to LRs
for programs. To allow humans access to the platform a central web application will
be developed. It will communicate with the platform core by a HTTP, JSON based
REST API. The user will be able to access any functionality provided by the platform
API. The results will be displayed on the screen by interactive widgets. Each of the
LRs will have a specific JavaScript widget that will graphically present the requested
resource. For example, in case of a wordnet, it can be an interactive graph that shows
the synsets and all related synsets. In case a specific resource widget is not available
(or not yet developed), the generic one will be called. It will use the basic HTML
result from a lexical microservice (the result of the getHTML function of the lexical
microservice).
    Moreover, the user will be able to easily search the LexP resources. Thus, LexP
expands in some sense the idea of Federated Content Search to the federated lexical
resources search. Technical users, despite the easier download of the whole resources
in accordance with their licences, will be able to download selected combinations of
resources or their parts as a graph.


5       Illustration: Integration of Polish Lexical Resources
Integration of a set of comprehensive but heterogeneous and bilingual LRs for Polish
can be a first case study for LexP idea. The set includes:
    ● plWordNet 3.0 emo (Słowosieć)13 ([12]) - a very large wordnet for Polish,
13
     http://plwordnet.pwr.edu.pl
         partially manually annotated with sentiment and basic emotions ([24])
         emotive annotation - anchor elements: lemma (170k), lexical unit (245k),
         synset (184k),
     ● enWordNet 1.0 - a significantly expanded Princeton WordNet 3.1 ([20]) - a
         very large wordnet for English, plWordNet has been manually mapped onto
         it and vice versa - anchor elements: lemma (163k), lexical unit (215k), synset
         (124k),
     ● Walenty14 ([18]) - a Polish valence dictionary, describing both syntactic and
         semantic argument structures, frames are defined for lemmas and lexical
         units that correspond to large extent to lexical units from plWordNet -
         anchor elements: lemma (15k), lexical unit, frame,
     ● Polimorf15 - a Polish morphological dictionary and SGJP16 - a grammatical
         dictionary of Polish - anchor elements: word form (~4M), lemma,
     ● NELexicon 2.017 - a lexicon of Polish Proper Names described with semantic
         categories, - anchor elements: lemma (~2.4M), synset (representing semantic
         classes),
     ● MWELexicon18 - a lexicon of Polish Multi-word Expressions described by
         their lexicon-syntactic structures, all MWEs are described as lemmas in
         plWordNet 3.0 emo - anchor elements: word form, lemma (54k),
     ● Hask19 ([17]) - a set of collocational databases - anchor elements: word form,
         lemma (150k for English).
    All the LRs mentioned above form a huge system, but they are not now
connected for browsing, and a user needs to consult several different specialised
browsers to learn how much information he can obtain from the system. However,
there are web applications for all these LRs, they already offer some presentation
formats for the web, so construction of LexP components for them should not be a
very difficult exercise.
    A minimal set of anchor element types provides links between all these resources.
So having the exercise done, a user can come with a word form, e.g. from a text, next
he can learn potential lemmas (highlighted in the presentation format) from the
morphological components, navigate through lemma links to plWordNet component,
check the possible valence frames in Walenty component, collocations from Hask,
learn about potential translations of the lexical meanings through mapping presented
by plWordNet component etc.




14
   http://zil.ipipan.waw.pl/Walenty
15
   http://zil.ipipan.waw.pl/PoliMorf
16
   http://sgjp.pl/leksemy/
17
   http://hdl.handle.net/11321/247
18
   http://hdl.handle.net/11321/274
19
   http://pelcra.pl/hask_en/
6    Further Works
We have started implementing the first version of LexP for the use cases for Polish
LRs described shortly above. The idea of LexP has been thoroughly discussed inside
CLARIN and several groups declared support for it. This can be the first step for
collaborative development of LexP.
     LexP should allow for better promotion and accessibility of existing LRs. Non-
technical users will be able to discover and browse LRs from a single access point.
Technical user will see the content of many LRs in a single place. However, LexP
will not be a new `super-resource’ which fully integrates the information in the
various resources, at the cost of obscuring the individual sources. Instead, all LRs
linked to LexP will preserve their identity. LRs can be kept in the original sites, which
also allows for the possibility to provide access protected by authentication to those
LRs that require restricted access.
     LexP will be open for relatively easy linking of new resources to it. One of the
biggest problems to be solved is proper treatment of information about versions of
different resources, e.g. lexical units from Walenty correspond to a certain version of
plWordNet, while LexP in its simplest form will present the latest version of
plWordNet. There are several potential solutions, but a final one must preserve
simplicity of the LexP idea. The platform can be also a good tool for promoting the
need for developing one common format for LRs and converging descriptions of their
models.

Acknowledgments
    This work was co-financed as a part of the investment in the CLARIN-PL
research infrastructure (www.clarin-pl.eu) funded by the Polish Ministry of Science
and Higher Education.


References
    1.   Aguado-de-Cea, G., Montiel-Ponsoda, E., Kernerman, I., Ordan, N. (2016). From
         dictionaries to cross-lingual lexical resources. In: Kernerman Dictionary News, 24,
         pp. 25-31.
    2.   Bel, N., Poch, M., Toral, A. (2012). PANACEA (Platform for Automatic,
         Normalised Annotation and Cost-Effective Acquisition of Language Resources
         for Human Language Technologies). In Proceedings of the 16th Annual
         Conference of the European Association for Machine Translation: EAMT 2012:
         Trento Italy, May 28th - 30th 2012. pg. 90.
    3.   Bell, M.: SOA Modeling Patterns for Service-Oriented Discovery and Analysis.
         Wiley & Sons (2010).
    4.   Bond, F., Paik, K. (2012). A survey of wordnets and their licenses. In Proceedings
         of the 6th Global WordNet Conference (GWC 2012). Matsue. 64–71.
    5.   Bond, F., Foster, R. (2013). Linking and extending an open multilingual wordnet. In
         51st Annual Meeting of the Association for Computational Linguistics: ACL-2013.
         Sofia. 1352–1362. http://aclweb.org/anthology/P/P13/P13-1133.pdf
    6.   Dragoni, N., Giallorenzo , S., Lluch-Lafuente, A., Mazzara M., Montesi F., Mustafin
         R., Safina L.: Microservices: yesterday, today, and tomorrow, CoRR, vol
         abs/1606.04036 (2016).
7.    Eckle-Kohler, Gurevych, I., Hartmann, S., Matuschek, M., Meyer, Ch.M. (2013).
      UBY-LMF - exploring the boundaries of language-independent lexicon models, in
      Francopoulo, G. (ed.) LMF Lexical Markup Framework, ISTE / Wiley (2013).
8.    Fellbaum, Ch. (ed) (1998). WordNet: An electronic lexical database, MIT Press,
      Cambridge.
9.    Gurevych, I., Eckle-Kohler, J., Hartmann, S., Matuschek, M., Meyer, Ch.M., Wirth,
      Ch. (2012). UBY - A Large-Scale Unified Lexical-Semantic Resource Based on
      LMF. EACL 2012.
10.   Heinrich, V., Hinrichs, E. (2010). Standardizing Wordnets in the ISO Standard
      LMF: Wordnet-LMF for GermaNet. Proceedings of COLING 2010.
11.   Klimek, B., Brummer, M.. (2015). Enhancing lexicography with semantic language
      databases. In: Kernerman Dictionary News, 23, pp. 5-10.
12.   Maziarz, M., Piasecki, M., Rudnicka, E., Szpakowicz, S., Kędzia, P.: (2016)
      plWordNet 3.0 - a Comprehensive Lexical-Semantic Resource. In: Calzolari, N.,
      Matsumoto, Y., Prasad, R. (eds.), COLING 2016, 26th International Conference on
      Computational Linguistics, Proceedings of the Conference: Technical Papers,
      December 11-16, pp. 2259-2268, Osaka (2016).
13.   McCrae, J., Cimiano, J. P., Montiel-Ponsoda, (2012). Integrating WordNet and
      Wiktionary with lemon. In Linked Data in Linguistics. eds. Chiarcos, Ch., Nordhoff,
      S., Hellman, S. Springer.
14.   Mechura, M. (2012). Léacslann: A platform for building dictionary writing systems,
      Proceedings of the 15th Euralex International Congress. Oslo: 855-861.
15.   Mechura, M. (2016). Data Structures in Lexicography: from Trees to Graphs.
      RASLAN 2016 Recent Advances in Slavonic Natural Language Processing, 97.
16.   Pedersen, B. S., Nimb, S., Asmussen, J., Sørensen, N. H., Trap-Jensen, L. and
      Lorentzen, H. (2009). DanNet -- the challenge of compiling a WordNet for Danish by
      reusing a monolingual dictionary        Language Resources and Evaluation.
      Volume 43:3 pp. 269-299.
17.   Pęzik, Piotr. Graph-Based Analysis of Collocational Profiles. In Phraseologie Im
      Wörterbuch Und Korpus (Phraseology in Dictionaries and Corpora), edited by Vida
      Jesenšek and Peter Grzybek, 227–43. ZORA 97. Maribor, Bielsko‑ Biała, Budapest,
      Kansas, Praha: Filozofska fakuteta, 2014.
18.   Przepiórkowski, A. Hajnicz, E., Patejuk, A. Woliński, M., Skwarski, F. Świdziński,
      M. Walenty: Towards a comprehensive valence dictionary of Polish. In Nicoletta
      Calzolari, Khalid Choukri, Thierry Declerck, Hrafn Loftsson, Bente Maegaard,
      Joseph Mariani, Asuncion Moreno, Jan Odijk, and Stelios Piperidis, editors,
      Proceedings of the Ninth International Conference on Language Resources and
      Evaluation, LREC 2014, pages 2785–2792, Reykjavík, Iceland, 2014. ELRA.
19.   Richardson, Ch. (2016). What are microservices? http://microservices.io/
20.   Rudnicka, E., Witkowski, W., Kaliński M. (2015). “Towards the Extension of
      Princeton WordNet”. Cognitive Studies 15, 335-351. Retrieved from:
      https://ispan.waw.pl/journals/index.php/cs-ec/article/download/cs.2015.023/1774.
21.   Wolff, E. (2016). Microservices: Flexible Software Architectures, Addison-Wesley.
22.   Vossen, P., Soria, C. , Monachini, M. (2013). Wordnet-LMF: A Standard
      Representation for Multilingual Wordnets. In {LMF} - Lexical Markup Framework.
      ed.. Francopoulo, G. ISTE Ltd + John Wiley \& sons, Inc.
23.   Vossen P., Bond, F., McCrae, J., Fellbaum, Ch. (2016). CILI: the Collaborative
      Interlingual Index. In Eighth meeting of the Global WordNet Conference (GWC
      2016), Bucharest.
24.   Zaśko-Zielińska, M., Piasecki, M., Szpakowicz, S. (2015). A Large Wordnet-based
      Sentiment Lexicon for Polish. In Proceedings of RANLP 2015. pp.721-730.