Stelios Piperidis

Also published as: S. Piperidis, Stelios Piperdis

2022

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Constructing Parallel Corpora from COVID-19 News using MediSys Metadata
Dimitrios Roussis | Vassilis Papavassiliou | Sokratis Sofianopoulos | Prokopis Prokopidis | Stelios Piperidis
Proceedings of the Thirteenth Language Resources and Evaluation Conference

This paper presents a collection of parallel corpora generated by exploiting the COVID-19 related dataset of metadata created with the Europe Media Monitor (EMM) / Medical Information System (MediSys) processing chain of news articles. We describe how we constructed comparable monolingual corpora of news articles related to the current pandemic and used them to mine about 11.2 million segment alignments in 26 EN-X language pairs, covering most official EU languages plus Albanian, Arabic, Icelandic, Macedonian, and Norwegian. Subsets of this collection have been used in shared tasks (e.g. Multilingual Semantic Search, Machine Translation) aimed at accelerating the creation of resources and tools needed to facilitate access to information in the COVID-19 emergency situation.

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SciPar: A Collection of Parallel Corpora from Scientific Abstracts
Dimitrios Roussis | Vassilis Papavassiliou | Prokopis Prokopidis | Stelios Piperidis | Vassilis Katsouros
Proceedings of the Thirteenth Language Resources and Evaluation Conference

This paper presents SciPar, a new collection of parallel corpora created from openly available metadata of bachelor theses, master theses and doctoral dissertations hosted in institutional repositories, digital libraries of universities and national archives. We describe first how we harvested and processed metadata from 86, mainly European, repositories to extract bilingual titles and abstracts, and then how we mined high quality sentence pairs in a wide range of scientific areas and sub-disciplines. In total, the resource includes 9.17 million segment alignments in 31 language pairs and is publicly available via the ELRC-SHARE repository. The bilingual corpora in this collection could prove valuable in various applications, such as cross-lingual plagiarism detection or adapting Machine Translation systems for the translation of scientific texts and academic writing in general, especially for language pairs which include English.

This paper provides an overview of the ongoing European Language Equality(ELE) project, an 18-month action funded by the European Commission which involves 52 partners. The primary goal of ELE is to prepare the European Language Equality Programme, in the form of a strategic research, innovation and implementation agenda and a roadmap for achieving full digital language equality (DLE) in Europe by 2030.

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Categorizing legal features in a metadata-oriented task: defining the conditions of use
Mickaël Rigault | Victoria Arranz | Valérie Mapelli | Penny Labropoulou | Stelios Piperidis
Proceedings of the Workshop on Ethical and Legal Issues in Human Language Technologies and Multilingual De-Identification of Sensitive Data In Language Resources within the 13th Language Resources and Evaluation Conference

In recent times, more attention has been brought by the Human Language Technology (HLT) community to the legal framework for making available and reusing Language Resources (LR) and tools. Licensing is now an issue that is foreseen in most research projects and that is essential to provide legal certainty for repositories when distributing resources. Some repositories such as Zenodo or Quantum Stat do not offer the possibility to search for resources by licenses which can turn the searching for relevant resources a very complex task. Other repositories such as Hugging Face propose a search feature by license which may make it difficult to figure out what use can be made of such resources. During the European Language Grid (ELG) project, we moved a step forward to link metadata with the terms and conditions of use. In this paper, we document the process we undertook to categorize legal features of licenses listed in the SPDX license list and widely used in the HLT community as well as those licenses used within the ELG platform

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Introducing the Digital Language Equality Metric: Technological Factors
Federico Gaspari | Owen Gallagher | Georg Rehm | Maria Giagkou | Stelios Piperidis | Jane Dunne | Andy Way
Proceedings of the Workshop Towards Digital Language Equality within the 13th Language Resources and Evaluation Conference

This paper introduces the concept of Digital Language Equality (DLE) developed by the EU-funded European Language Equality (ELE) project, and describes the associated DLE Metric with a focus on its technological factors (TFs), which are complemented by situational contextual factors. This work aims at objectively describing the level of technological support of all European languages and lays the foundation to implement a large-scale EU-wide programme to ensure that these languages can continue to exist and prosper in the digital age, to serve the present and future needs of their speakers. The paper situates this ongoing work with a strong European focus in the broader context of related efforts, and explains how the DLE Metric can help track the progress towards DLE for all languages of Europe, focusing in particular on the role played by the TFs. These are derived from the European Language Grid (ELG) Catalogue, that provides the empirical basis to measure the level of digital readiness of all European languages. The DLE Metric scores can be consulted through an online interactive dashboard to show the level of technological support of each European language and track the overall progress toward DLE.

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Collaborative Metadata Aggregation and Curation in Support of Digital Language Equality Monitoring
Maria Giagkou | Stelios Piperidis | Penny Labropoulou | Miltos Deligiannis | Athanasia Kolovou | Leon Voukoutis
Proceedings of the Workshop Towards Digital Language Equality within the 13th Language Resources and Evaluation Conference

The European Language Equality (ELE) project develops a strategic research, innovation and implementation agenda (SRIA) and a roadmap for achieving full digital language equality in Europe by 2030. Key component of the SRIA development is an accurate estimation of the current standing of languages with respect to their technological readiness. In this paper we present the empirical basis on which such estimation is grounded, its starting point and in particular the automatic and collaborative methods used for extending it. We focus on the collaborative expert activities, the challenges posed, and the solutions adopted. We also briefly present the dashboard application developed for querying and visualising the empirical data as well as monitoring and comparing the evolution of technological support within and across languages.

2021

Europe is a multilingual society, in which dozens of languages are spoken. The only option to enable and to benefit from multilingualism is through Language Technologies (LT), i.e., Natural Language Processing and Speech Technologies. We describe the European Language Grid (ELG), which is targeted to evolve into the primary platform and marketplace for LT in Europe by providing one umbrella platform for the European LT landscape, including research and industry, enabling all stakeholders to upload, share and distribute their services, products and resources. At the end of our EU project, which will establish a legal entity in 2022, the ELG will provide access to approx. 1300 services for all European languages as well as thousands of data sets.

2020

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Proceedings of the 1st International Workshop on Language Technology Platforms
Georg Rehm | Kalina Bontcheva | Khalid Choukri | Jan Hajič | Stelios Piperidis | Andrejs Vasiļjevs
Proceedings of the 1st International Workshop on Language Technology Platforms

CLARIN is a European Research Infrastructure providing access to digital language resources and tools from across Europe and beyond to researchers in the humanities and social sciences. This paper focuses on CLARIN as a platform for the sharing of language resources. It zooms in on the service offer for the aggregation of language repositories and the value proposition for a number of communities that benefit from the enhanced visibility of their data and services as a result of integration in CLARIN. The enhanced findability of language resources is serving the social sciences and humanities (SSH) community at large and supports research communities that aim to collaborate based on virtual collections for a specific domain. The paper also addresses the wider landscape of service platforms based on language technologies which has the potential of becoming a powerful set of interoperable facilities to a variety of communities of use.

With regard to the wider area of AI/LT platform interoperability, we concentrate on two core aspects: (1) cross-platform search and discovery of resources and services; (2) composition of cross-platform service workflows. We devise five different levels (of increasing complexity) of platform interoperability that we suggest to implement in a wider federation of AI/LT platforms. We illustrate the approach using the five emerging AI/LT platforms AI4EU, ELG, Lynx, QURATOR and SPEAKER.

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Verbal Aggression as an Indicator of Xenophobic Attitudes in Greek Twitter during and after the Financial Crisis
Maria Pontiki | Maria Gavriilidou | Dimitris Gkoumas | Stelios Piperidis
Proceedings of the Workshop about Language Resources for the SSH Cloud

We present a replication of a data-driven and linguistically inspired Verbal Aggression analysis framework that was designed to examine Twitter verbal attacks against predefined target groups of interest as an indicator of xenophobic attitudes during the financial crisis in Greece, in particular during the period 2013-2016. The research goal in this paper is to re-examine Verbal Aggression as an indicator of xenophobic attitudes in Greek Twitter three years later, in order to trace possible changes regarding the main targets, the types and the content of the verbal attacks against the same targets in the post crisis era, given also the ongoing refugee crisis and the political landscape in Greece as it was shaped after the elections in 2019. The results indicate an interesting rearrangement of the main targets of the verbal attacks, while the content and the types of the attacks provide valuable insights about the way these targets are being framed as compared to the respective dominant perceptions and stereotypes about them during the period 2013-2016.

Multilingualism is a cultural cornerstone of Europe and firmly anchored in the European treaties including full language equality. However, language barriers impacting business, cross-lingual and cross-cultural communication are still omnipresent. Language Technologies (LTs) are a powerful means to break down these barriers. While the last decade has seen various initiatives that created a multitude of approaches and technologies tailored to Europe’s specific needs, there is still an immense level of fragmentation. At the same time, AI has become an increasingly important concept in the European Information and Communication Technology area. For a few years now, AI – including many opportunities, synergies but also misconceptions – has been overshadowing every other topic. We present an overview of the European LT landscape, describing funding programmes, activities, actions and challenges in the different countries with regard to LT, including the current state of play in industry and the LT market. We present a brief overview of the main LT-related activities on the EU level in the last ten years and develop strategic guidance with regard to four key dimensions.

With 24 official EU and many additional languages, multilingualism in Europe and an inclusive Digital Single Market can only be enabled through Language Technologies (LTs). European LT business is dominated by hundreds of SMEs and a few large players. Many are world-class, with technologies that outperform the global players. However, European LT business is also fragmented – by nation states, languages, verticals and sectors, significantly holding back its impact. The European Language Grid (ELG) project addresses this fragmentation by establishing the ELG as the primary platform for LT in Europe. The ELG is a scalable cloud platform, providing, in an easy-to-integrate way, access to hundreds of commercial and non-commercial LTs for all European languages, including running tools and services as well as data sets and resources. Once fully operational, it will enable the commercial and non-commercial European LT community to deposit and upload their technologies and data sets into the ELG, to deploy them through the grid, and to connect with other resources. The ELG will boost the Multilingual Digital Single Market towards a thriving European LT community, creating new jobs and opportunities. Furthermore, the ELG project organises two open calls for up to 20 pilot projects. It also sets up 32 national competence centres and the European LT Council for outreach and coordination purposes.

The current scientific and technological landscape is characterised by the increasing availability of data resources and processing tools and services. In this setting, metadata have emerged as a key factor facilitating management, sharing and usage of such digital assets. In this paper we present ELG-SHARE, a rich metadata schema catering for the description of Language Resources and Technologies (processing and generation services and tools, models, corpora, term lists, etc.), as well as related entities (e.g., organizations, projects, supporting documents, etc.). The schema powers the European Language Grid platform that aims to be the primary hub and marketplace for industry-relevant Language Technology in Europe. ELG-SHARE has been based on various metadata schemas, vocabularies, and ontologies, as well as related recommendations and guidelines.

2018

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The ILSP/ARC submission to the WMT 2018 Parallel Corpus Filtering Shared Task
Vassilis Papavassiliou | Sokratis Sofianopoulos | Prokopis Prokopidis | Stelios Piperidis
Proceedings of the Third Conference on Machine Translation: Shared Task Papers

This paper describes the submission of the Institute for Language and Speech Processing/Athena Research and Innovation Center (ILSP/ARC) for the WMT 2018 Parallel Corpus Filtering shared task. We explore several properties of sentences and sentence pairs that our system explored in the context of the task with the purpose of clustering sentence pairs according to their appropriateness in training MT systems. We also discuss alternative methods for ranking the sentence pairs of the most appropriate clusters with the aim of generating the two datasets (of 10 and 100 million words as required in the task) that were evaluated. By summarizing the results of several experiments that were carried out by the organizers during the evaluation phase, our submission achieved an average BLEU score of 26.41, even though it does not make use of any language-specific resources like bilingual lexica, monolingual corpora, or MT output, while the average score of the best participant system was 27.91.

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Managing Public Sector Data for Multilingual Applications Development
Stelios Piperidis | Penny Labropoulou | Miltos Deligiannis | Maria Giagkou
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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European Language Resource Coordination: Collecting Language Resources for Public Sector Multilingual Information Management
Andrea Lösch | Valérie Mapelli | Stelios Piperidis | Andrejs Vasiļjevs | Lilli Smal | Thierry Declerck | Eileen Schnur | Khalid Choukri | Josef van Genabith
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

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Discovering Parallel Language Resources for Training MT Engines
Vassilis Papavassiliou | Prokopis Prokopidis | Stelios Piperidis
Proceedings of the Eleventh International Conference on Language Resources and Evaluation (LREC 2018)

2016

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The ILSP/ARC submission to the WMT 2016 Bilingual Document Alignment Shared Task
Vassilis Papavassiliou | Prokopis Prokopidis | Stelios Piperidis
Proceedings of the First Conference on Machine Translation: Volume 2, Shared Task Papers

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Parallel Global Voices: a Collection of Multilingual Corpora with Citizen Media Stories
Prokopis Prokopidis | Vassilis Papavassiliou | Stelios Piperidis
Proceedings of the Tenth International Conference on Language Resources and Evaluation (LREC'16)

We present a new collection of multilingual corpora automatically created from the content available in the Global Voices websites, where volunteers have been posting and translating citizen media stories since 2004. We describe how we crawled and processed this content to generate parallel resources comprising 302.6K document pairs and 8.36M segment alignments in 756 language pairs. For some language pairs, the segment alignments in this resource are the first open examples of their kind. In an initial use of this resource, we discuss how a set of document pair detection algorithms performs on the Greek-English corpus.

2015

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A Data Sharing and Annotation Service Infrastructure
Stelios Piperidis | Dimitrios Galanis | Juli Bakagianni | Sokratis Sofianopoulos
Proceedings of ACL-IJCNLP 2015 System Demonstrations

2014

This article provides an overview of the dissemination work carried out in META-NET from 2010 until early 2014; we describe its impact on the regional, national and international level, mainly with regard to politics and the situation of funding for LT topics. This paper documents the initiatives work throughout Europe in order to boost progress and innovation in our field.

This paper presents META-SHARE (www.meta-share.eu), an open language resource infrastructure, and its usage since its Europe-wide deployment in early 2013. META-SHARE is a network of repositories that store language resources (data, tools and processing services) documented with high-quality metadata, aggregated in central inventories allowing for uniform search and access. META-SHARE was developed by META-NET (www.meta-net.eu) and aims to serve as an important component of a language technology marketplace for researchers, developers, professionals and industrial players, catering for the full development cycle of language technology, from research through to innovative products and services. The observed usage in its initial steps, the steadily increasing number of network nodes, resources, users, queries, views and downloads are all encouraging and considered as supportive of the choices made so far. In tandem, take-up activities like direct linking and processing of datasets by language processing services as well as metadata transformation to RDF are expected to open new avenues for data and resources linking and boost the organic growth of the infrastructure while facilitating language technology deployment by much wider research communities and industrial sectors.

2013

2012

The FLaReNet Strategic Agenda highlights the most pressing needs for the sector of Language Resources and Technologies and presents a set of recommendations for its development and progress in Europe, as issued from a three-year consultation of the FLaReNet European project. The FLaReNet recommendations are organised around nine dimensions: a) documentation b) interoperability c) availability, sharing and distribution d) coverage, quality and adequacy e) sustainability f) recognition g) development h) infrastructure and i) international cooperation. As such, they cover a broad range of topics and activities, spanning over production and use of language resources, licensing, maintenance and preservation issues, infrastructures for language resources, resource identification and sharing, evaluation and validation, interoperability and policy issues. The intended recipients belong to a large set of players and stakeholders in Language Resources and Technology, ranging from individuals to research and education institutions, to policy-makers, funding agencies, SMEs and large companies, service and media providers. The main goal of these recommendations is to serve as an instrument to support stakeholders in planning for and addressing the urgencies of the Language Resources and Technologies of the future.

This paper presents a metadata model for the description of language resources proposed in the framework of the META-SHARE infrastructure, aiming to cover both datasets and tools/technologies used for their processing. It places the model in the overall framework of metadata models, describes the basic principles and features of the model, elaborates on the distinction between minimal and maximal versions thereof, briefly presents the integrated environment supporting the LRs description and search and retrieval processes and concludes with work to be done in the future for the improvement of the model.

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The META-SHARE Language Resources Sharing Infrastructure: Principles, Challenges, Solutions
Stelios Piperidis
Proceedings of the Eighth International Conference on Language Resources and Evaluation (LREC'12)

Language resources have become a key factor in the development cycle of language technology. The current prevailing methodologies, the sheer number of languages and the vast volumes of digital content together with the wide palette of useful content processing applications, render new models for managing the underlying language resources indispensable. This paper presents META-SHARE, an open resource exchange infrastructure, which aims to boost visibility, documentation, identification, openness and sharing, collaboration, preservation and interoperability of language data and basic language processing tools. META-SHARE is implemented as a network of distributed repositories of language resources. It offers providers and consumers of resources the necessary functionalities for describing, storing, searching, licensing and downloading language resources in a single integrated technical platform. META-SHARE favours and aligns itself with the growing open data and open source tools movement. To this end, it has prepared the necessary underlying legal framework consisting of a Charter for language resource sharing, as well as a set of licensing templates aiming to act as recommended licence models in an attempt to facilitate the legal interoperability of language resources. In its current version, META-SHARE features 13 resource repositories, with over 1200 resource packages.

2011

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Proceedings of the Workshop on Language Resources, Technology and Services in the Sharing Paradigm
Nicoletta Calzolari | Toru Ishida | Stelios Piperidis | Virach Sornlertlamvanich
Proceedings of the Workshop on Language Resources, Technology and Services in the Sharing Paradigm

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Proceedings of the Workshop on Language Technologies for Digital Humanities and Cultural Heritage
Cristina Vertan | Milena Slavcheva | Petya Osenova | Stelios Piperidis
Proceedings of the Workshop on Language Technologies for Digital Humanities and Cultural Heritage

2010

In this paper we present the LREC Map of Language Resources and Tools, an innovative feature introduced with this LREC. The purpose of the Map is to shed light on the vast amount of resources and tools that represent the background of the research presented at LREC, in the attempt to fill in a gap in the community knowledge about the resources and tools that are used or created worldwide. It also aims at a change of culture in the field, actively engaging each researcher in the documentation task about resources. The Map has been developed on the basis of the information provided by LREC authors during the submission of papers to the LREC 2010 conference and the LREC workshops, and contains information about almost 2000 resources. The paper illustrates the motivation behind this initiative, its main characteristics, its relevance and future impact in the field, the metadata used to describe the resources, and finally presents some of the most relevant findings.

Currently, research infrastructures are being designed and established in many disciplines since they all suffer from an enormous fragmentation of their resources and tools. In the domain of language resources and tools the CLARIN initiative has been funded since 2008 to overcome many of the integration and interoperability hurdles. CLARIN can build on knowledge and work from many projects that were carried out during the last years and wants to build stable and robust services that can be used by researchers. Here service centres will play an important role that have the potential of being persistent and that adhere to criteria as they have been established by CLARIN. In the last year of the so-called preparatory phase these centres are currently developing four use cases that can demonstrate how the various pillars CLARIN has been working on can be integrated. All four use cases fulfil the criteria of being cross-national.

2009

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Machine Translation and its Philosophical Accounts
Stelios Piperidis
Proceedings of the EACL 2009 Workshop on the Interaction between Linguistics and Computational Linguistics: Virtuous, Vicious or Vacuous?

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Proceedings of the Workshop Multilingual resources, technologies and evaluation for central and Eastern European languages
Elena Paskaleva | Stelios Piperidis | Milena Slavcheva | Cristina Vertan
Proceedings of the Workshop Multilingual resources, technologies and evaluation for central and Eastern European languages

2008

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Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)
Nicoletta Calzolari | Khalid Choukri | Bente Maegaard | Joseph Mariani | Jan Odijk | Stelios Piperidis | Daniel Tapias
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

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Condensing Sentences for Subtitle Generation
Prokopis Prokopidis | Vassia Karra | Aggeliki Papagianopoulou | Stelios Piperidis
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

Text condensation aims at shortening the length of an utterance without losing essential textual information. In this paper, we report on the implementation and preliminary evaluation of a sentence condensation tool for Greek using a manually constructed table of 450 lexical paraphrases, and a set of rules that delete syntactic subtrees that carry minor semantic information. Evaluation on two-sentence sets show promising results regarding grammaticality and semantic acceptability of compressed versions.

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Foundation of a Component-based Flexible Registry for Language Resources and Technology
Daan Broeder | Thierry Declerck | Erhard Hinrichs | Stelios Piperidis | Laurent Romary | Nicoletta Calzolari | Peter Wittenburg
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

Within the CLARIN e-science infrastructure project it is foreseen to develop a component-based registry for metadata for Language Resources and Language Technology. With this registry it is hoped to overcome the problems of the current available systems with respect to inflexible fixed schema, unsuitable terminology and interoperability problems. The registry will address interoperability needs by refering to a shared vocabulary registered in data category registries as they are suggested by ISO.

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Building a Greek corpus for Textual Entailment
Evi Marzelou | Maria Zourari | Voula Giouli | Stelios Piperidis
Proceedings of the Sixth International Conference on Language Resources and Evaluation (LREC'08)

The paper reports on completed work aimed at the creation of a resource, namely, the Greek Textual Entailment Corpus (GTEC) that is appropriate for guiding training and evaluation of a system that recognizes Textual Entailment in Greek texts. The corpus of textual units was collected in view of a range of NLP applications, where semantic interpretation is of paramount importance, and it was manually annotated at the level of Textual Entailment. Moreover, a number of linguistic annotations were also integrated that were deemed useful for prospect system developers. The critical issue was the development of a final resource that is re-usable and adaptable to different NLP systems, in order to either enhance their accuracy or to evaluate their output. We are hereby focusing on the methodological issues underpinning data selection and annotation. An initial approach towards the development of a system catering for the automatic Recognition of Textual Entailment in Greek is also presented and preliminary results are reported.

2006

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Language Resources Production Models: the Case of the INTERA Multilingual Corpus and Terminology
Maria Gavrilidou | Penny Labropoulou | Stelios Piperidis | Voula Giouli | Nicoletta Calzolari | Monica Monachini | Claudia Soria | Khalid Choukri
Proceedings of the Fifth International Conference on Language Resources and Evaluation (LREC’06)

This paper reports on the multilingual Language Resources (MLRs), i.e. parallel corpora and terminological lexicons for less widely digitally available languages, that have been developed in the INTERA project and the methodology adopted for their production. Special emphasis is given to the reality factors that have influenced the MLRs development approach and their final constitution. Building on the experience gained in the project, a production model has been elaborated, suggesting ways and techniques that can be exploited in order to improve LRs production taking into account realistic issues.

2004