Amblard Maxime
email: maxime.amblard@univ-lorraine.fr

Miguel Couceiro
email: miguel.couceiro@univ-lorraine.fr

A Broad NLP Training from Speech to Knowledge

In 2018, the Master of Science programe in NLP 1 opened at the IDMC 2 . Far from being a creation ex-nihilo, it is the product of a history and many reflections on the field and its teaching. This article proposes epistemological and critical elements on the opening and maintainance of this so far new master's programe in NLP.

This article discusses the epistemological background of the creation of the Master of Science program in natural language processing (NLP) at the University of Lorraine in 2018. It puts forward a critical analysis of the environment, of the methodology chosen to produce this program, and it highlights the salient elements for the teaching of NLP.

Currently, the master's degree is taught at the IDMC of the University de Lorraine. It is accessible to students trained within the undergraduate programe of the institute or to students that successfully apply to the programe. A jury from the pedagogical team evaluates the adequacy of the candidates' profile with the requirements and expectations of the training. For the detailed description of the master's degree in NLP, please visit pour dedicated website 3 .

We propose a singular training at the French level, and probably at the international level. It is a Master's degree that gives the tools and methods to carry out language data processing. If NLP is at the heart of the training, we have opened up to speech and knowledge processing. The objective is to train tomorrow's professionals in both the economic and academic fields for language data processing.

In this article we present the Master's degree in NLP at the IDMC. After quickly reviewing the

History

The Department of Mathematics and Computer Science at the University of Nancy 2 pursued a policy of opening up both of these disciplines to human and social sciences. At the beginning of the 2000s, the department proposed a training program based on these aspects by integrating economics and business management. Following this interdisciplinary view, the pedagogical team created a bachelor's degree program in cognitive sciences. Several thematic openings were made, in particular, towards psychology, biology, linguistics and neurosciences. The dynamics was successful and paved the way to the opening of a complete master's programe in Cognitive Sciences (two years). The core of the training has clearly been the cognitive sciences.

Research environment

The French higher education and research implies that research and teaching are carried out in different components. Thus, the teachers carry out their research in a different research laboratory. In Nancy (France), two laboratories are particularly concerned: Loria 4 and ATILF 5 . These two laboratories are mixed research units, i.e., university laboratories co-accredited by a research center. This co-accreditation makes it possible to integrate staff who only have research duties. It appears as a quality label for the research carried out. The ATILF is co-accredited by the CNRS 6 and the Loria is co-accredited by the CNRS and Inria 7 . The two laboratories ensure a sustained research activity in the field in Nancy. ATILF is organized with three themes: lexicons; corpora and knowledge; and dynamic aspects of language. Atilf is known for the Trésor de la Langue Française Informatisé, a large online dictionary of French.

Research in computer science is carried out jointly by loria and the Inria Nancy Grand-Est center. Beyond institutional issues, the researchers work jointly on all computer science domains. In particular, Loria is organised into research departments, one of which, the largest, is entirely devoted to NLP research. The department gathers about fifty permanent staff members in eight teams of different sizes (Cello, Team K, Multispeech, Orpailleur, Read, SMarT, Sémagramme, Synalp).

Creation of a training program in NLP

The dynamics of the teaching of mathematics and computer science open to other disciplines, and the strong research activity in Nancy have proven to be a favorable ground for the creation of a training program in NLP. In the early 2000s, the Master's degree in Cognitive Science integrated languagerelated issues into some of its courses. A DESS, an applied training program at the master's level, was also opened for a few years under the direction of Fiammetta Nammer and Yannick Toussaint. However, as the people in charge were not in the teaching component and the theme was not yet explicitly recognized by the French industry, this attempt had to be stopped quickly. It nevertheless established the possibility of developing a curriculum in NLP.

It was in 2005 that the main turning point took place. At that time, a double dynamic was set up, embodied by Patrick Blackburn and Guy Perrier. The latter was a university professor in computer science and set up a training program integrating students from computer science programs with linguistics programs within the Master's degree in Cognitive Science. During this time, Patrick Blackburn was working on the creation of the Erasmus Mundus Language and Communication Technologies consortium, of which Nancy would be the partner for France.

The Erasmus Mundus european program on Language and Communication Technologies8 is a joint master's program between seven European Universities. The program is supported by Europe and propose grants for students. They are selected at the international level for the qualitiy of their trainning and motivation. Some students integrate the program as self-funded. Each student spends one year in one partner university of the consortium and the second year in another one. They share some activities and events all together during the year.

In

Other contextual elements

In addition to the synergy between the cognitive science and NLP courses, it is worth noting the presence of other important training factors. On the one hand, there is a Master's degree in Language Sciences as well as a second Erasmus Mundu program specialized in Lexicology: EMLEX12 . This program works very differently because the classes share semesters together on a given campus. The students are therefore not systematically present in Nancy. In all cases, they are also international students selected for their results and motivation.

In addition, the Université de Lorraine integrates engineering schools into its structure. In particular, the Ecole des Mines de Nancy. This engineering training is recognized as being of high quality in France. However, students from this type of training rarely go on to complete a PhD, despite their qualities. For those who are interested in this type of opening, it is traditional to offer double courses with Master's programs. Thus we have set up an exchange protocol that allows students from the Ecole des Mines to join the Master's program during the last year of the program.

All these elements made the Université de Lorraine a suitable environment for developing the master's program in NLP.

Definition of the NLP program

The first question is to define for whom the program is intended. To do this we went back to the ambition we wanted to give to the program. Once the objective was clarified, we were able to work on defining the content of the program.

Program's objectives

The first observation made in 2016 was that there was an effective increase in the need for NLP, both for industrial issues and for the development of research. At that time, a very strong dynamic was already in place, driven by AI and deep learning.

We realized that the training we had developed until then was attached to a more traditional definition of NLP, rooted in computer science and linguistics. Its objectives being mainly to accompany students towards research, this was not very surprising, but it proved to be out of step with scientific and societal evolutions.

The project took shape in the idea of considering that students should leave the Master's program for industry as much as for research. We already considered that a significant part of the companies concerned were also concerned with research issues. This shift towards more applicative issues also seemed necessary to us to be able to integrate more students into the training.

Moreover, our experience with the second year of the Master's program showed us that the students who successfully completed the program could have very heterogeneous profiles. The challenge for us was more to define the type of profile that we wanted to find at the end of the training and to propose paths to bring the students there. This being the case, in view of the size of the classes, it was not possible to multiply the paths and above all, it seemed important to us that the profiles be built in interaction with each other. To achieve this, we need to have a precise vision of the type of training we can accept.

We have therefore chosen to build a training program centered on computer science and mathemat-ics for the NLP that is as open to research issues as it is to applications.

Methodology

To build the program, a project manager was appointed in 2015 by the teaching component in the person of Maxime Amblard with the task to design a project to be presented to the University in June 2016. Some others are used are underpinning as [START_REF] Bender | Building a flexible, collaborative, intensive master's program in computational linguistics[END_REF].

The project manager made the choice to start from scratch, considering that the contents present at that time needed to be renovated. He set up a working group gathering members of the Loria and ATILF teams working on language data who wanted to invest in the new training. The aim was to integrate new colleagues, new views and possibly new themes/issues.

A shared space was set up online allowing all parties to access the working material as it became available. The working group started with 13 people and ended up with 25 people. It was decided to meet the equivalent of once a month until July 2026. After each meeting, the leader wrote a report that was sent to all members, as well as a doodle to choose the date of the next meeting and the agenda of this meeting. The participants thus had the agenda well in advance, which allowed them to prepare the meeting as well as possible or to send their points of view and their work in case of absence. This methodology ensured that no information was lost and that the work dynamic was maintained throughout the year. In addition, meeting times were strictly adhered to. We return to the major orientations in the following section.

Higher education and research are undergoing numerous transformations. This is obviously the case in France. In particular, at that time, major programs were being launched and it was important to position training in this ecosystem. In the end, we quickly dismissed this issue, considering that the constitution of a scientifically solid program would always be easier to defend.

After several discussion sessions, we came to conclusions:

• the environment has many competences as well in data processing as in linguistics, which moreover with habits of work in common

• the Erasmus Mundus LCT obliged us to teach in English, which is not always easy in France, but this should be a strength for the recruitment of international students

• we had a scientific positioning neither in computer science nor in linguistics, clearly based on mathematics and computer science

• it is now possible to award a French diploma in NLP

• the needs both in the industrial and academic world are important

We have also considered two hypotheses on the organization of the training: the non-opening of the training to distance learning because it requires another type of organization that we cannot propose for now, and the possibility of carrying out the training in alternation. This program is a French specificity which allows students to study while being employed by a company. Thus, the training alternates (in the literal sense) periods of training at the institute and periods of work in a company.

One important aspect is to have concluded that if we have many strengths in the field of NLP, we have the specificity of covering a wider field of language data processing. If we are not the only ones in France, we wanted to make a specificity of our mathematic and computer science positioning in the field of language data processing. We have therefore decided to offer a curriculum entitled "Computer Science, Speech, Text and Knowledge". Thus, the new program deals with speech processing, NLP and knowledge. It is obvious that the reconciliation of formal and statistics tools operated in the last ten years facilitates this closeness.

Broad Program Directions

We have therefore chosen to integrate students whose initial training is either in computer science or linguistics, with an appetite for formalization, programming and mathematics. A single pathway is proposed through the training that brings together these different profiles. The objective is to bring all students to the same exit point. Beyond this declaration of intent, it is obvious that we cannot transform in two years linguists who have never done programming into operational computer scientists, just as we cannot transform computer scientists into linguists in the same time. On the other hand, students must be comfortable enough to overcome the paralysis of working in a new field, to go beyond naive approaches and above all to be able to discuss the different aspects precisely with specialists in the other field. To achieve this, there is nothing better than to mix these profiles throughout the training.

This mixing adds entropy to the construction of individual paths. To compensate for this, we have proposed a very legible and regular architecture in the training. This apparently very rigid organization allows students to build their path together.

Moreover, as we have already mentioned, the aim is to offer a course with a strong research component, while at the same time offering numerous applications.

It was therefore decided that the first year would serve as a substrate to establish the background by opening up to the problematic of long time.

The second year would focus on NLP topics, with many more applications and especially a significant amount of time devoted to an internship either in a laboratory or in a company. The training is given over two years, i.e. 4 semesters:

• two semesters of the first year of 260 effective teaching hours each -30 credits each

• one long semester of the second year of 350 effective hours of teaching each -30 credits

• one internship of at least 5 months (one semester) -30 credits

The architecture of each of the three semesters is the same with 5 teaching units of equal importance in the validation of the training. The organization of studies in France implies that each semester validates 30 credits (ECTS).

Renewal of Teaching Practices

As we have already mentioned, we did not want to transform our teaching practices by switching to distance learning, especially because we thought it was important to have different profiles working together. It is difficult to measure this at a distance.

However, we questioned these practices to propose more applied teaching or with effective data manipulation, as well as the implementation of group work, in particular in the form of projects.

Concerning the discovery of research, we propose a project in groups of 2 to 4 students, called "supervised project". This is a project carried out during the first year, at the initiative of a researcher, and which leads to the writing of two reports. The first part of the year is a bibliographic work. It consists of taking the time to read and understand scientific articles on the state of the art and to put them in perspective with the proposed project. The work is synthesized in a bibliographic report which opens to the second part of the work which is a more classical realization part. The students produce a report, which is a first experience of long writing before their final report of master, as well as a defense of 20 minutes in front of a jury and the presentation of a poster. The objective is to have them carry out a research project over a long period of time, with links to the literature on the one hand and actual achievements on the other, and also to master the codes of scientific presentation. This work often leads to publications in international conference workshops.

As an example, here are some titles of projects carried out in recent years on different themes: Speaker Adaptation Techniques for Automatic Speech Recognition, Testing Greenberg's Linguistic Universals on the Universal Dependencies Corpora using a Graph Rewriting tool, Does my question answer your answer, Anomaly detection with deep learning models, ... The counterpart of this work is the realization of an applied project, in group, also on the long time. It is set up in the second year by groups of 3 to 4 students. The initiative is left to the students, who are nevertheless supervised by two teachers. Once the application is identified, the students implement the concepts they have encountered in their training to produce an application. The functional and deployable applications are put online to showcase the work done. The students also produce a report explaining their approach and their achievement, and they make a defense. Here some examples of realization subjects:

• GECko+ is built on top of two Artificial Intelligence models in order to correct spelling and grammar mistakes, and tackling discourse fallacies with BERT [START_REF] Devlin | Bert: Pre-training of deep bidirectional transformers for language understanding[END_REF].

• Askme is a Question Answering model built on the Stanford Question Answering Dataset (SQuAD) with a fine-tuned BERT. Askme is able to automatically answer factual questions without being aware of the context.

• IGrander Essay: Automated Essay Grading systems provide an easy and time-efficient solution to essay scoring.

• Multilingual multispeaker expressive Textto-speech system: The main goal of this work is from text input to be able to generate speech with expressivity for multiple languages, which are currently French and English, with an end-to-end multilingual text-tospeech (TTS) system.

The first experiences have shown that both formats are very formative. It is common for groups of students to go from very enthusiastic to overwhelmed phases. In both cases, although very different from each other, the situation allows them to better understand where the interests of NLP are and especially where the difficulties are. Working over a long period of time shows them the importance of anticipating problems in both research and development. We make sure that the groups are mixed in terms of profiles to avoid the pitfall of groups stuck on IT developments, as well as groups missing out on linguistic issues. We note that an additional exercise is paper writing in the format of the main conferences in the field.

Support for internationalization

As part of the development of French universities, the gouvernement has set up the development of major projects, under the name Project Investment of the Future (PIA). The Université de Lorraine benefits from a major project of this type called Lorraine University of Excellence (LUE). This project covers several themes around systems engineering.

The training program has benefited from financial support from this program to support internationalization. For this purpose, we are translating the presentation documents into several languages, in particular into Russian, Persian, Greek and Turkish. The objective is to accompany as effectively as possible the arrival of students in the training.

In addition, we have made a promotional film for international students to highlight the necessary complementarity between computer science and linguistics that is achieved within our training. The production was made in a professional way by relying on the students and their profile. Once again, the aim is to highlight the diversity and quality of the students' profiles.

Program Design

Education

It is not a question here of making an advertising brochure of the training, also we do not give explic-itly the titles of each teaching unit. This being said, the training is thought to put forward continuum between the semesters, as much as possible on the whole training, at least between the semesters. It is this dynamic that we put forward. We invite the readers to refer to the descriptions of the training for more details. We have the three semesters with regular teaching. Units of the first semester are numbered 70X, ones of the second semester with 80X and those of the last semester with 90X, where X takes its value in {1, 2, 3, 4, 5}

The first units gathers the fundamental teachings in mathematics and computer science. For this unit, the continuum is natural: on one side probabilities and statistics -machine learning -neural network; on the other one programming -semantic web -data mining/recommendation 701 Probabilities, Statistics and Algorithms for AI:

The The second units gathers the teachings around corpora and formal toolsFor units two and three in the second year, we make sure to offer state of the art teaching applied to language data.. 702 Design and Acquisition of corpus: This course aims to introduce techniques of construction, structuring, annotating and archival of textual oral or multimodal corpora, which play an essential role in the analysis of the structure of spoken and written language, and on the other hand in the training and evaluation of NLP algorithms. This subject is complex as it is necessary that (1) the corpora be restricted to a reasonable size in order to guarantee the proper collection of corresponding data and that (2) this data sufficiently represents the phenomena studied (Written Corpora; and Spoken Corpora).

802 Formal Tools: This course unit is dedicate to the introduction to theoretical frameworks and logic used in symbolic approaches to the modeling of language. It consists of mathematical logic and of formal languages. The objective is to familiarize the students with these formal models, their properties, the demonstration techniques associated with them, and the notions of calculability and complexity.

902 Text and Speech Processing: Automatic processing of texts and speeches involves different methods of machine learning. This class will introduce these methods and illustrate their use through examples and practical application using tools developed (Speech processing, Processing Textual Data, Terminology and ontology).

The third units gathers the teaching on software engineering and data sciences. Finally, the fifth units is the project-based teaching that we have detailed above, to which we add language teaching (French for non-French speakers, English for the others). In the second year, we add opening lessons, in particular around ethical issues.

705 This course unit is composed of the first part of the year-long supervised project (which will be finalized in the second semester), as well as language classes. The project consists of group work (in pairs), which is supervised by researchers, in which the students will carry out the bibliographic part of the final report. Language classes will allow nonanglophone students to become more familiar with scientific english, the language in which all courses are conducted, whereas the french classes will facilitate non-francophone students' social and cultural integration. The course allows students to test their first skills acquired during the semester while synthesizing the different research issues concerned by a more open research topic. Students are evaluated on the acquisition of targeted skills, identified for the Sc. Master.

805 This course unit is made up of language classes as well as the second part of the yearlong supervised project (UE 705) which is finalized during the second semester. The second part of the year-long project begins by following through with the procedure introduced in the first semester groupwork, and leads up to the presentation at the end of the year, explaining the implementation of the project, which puts to test all of the skills the student acquires during the first year of the program. The language classes allow students to become more comfortable with the knowledge of scientific english.

905 Projects and Foreign Language: This course unit gathers many teaching including the project and language classes (Software project; Law and ethics; Research methods; Professional integration; Foreign language courses (French or English))

To compensate for the differences in levels, the technical courses of the first semester are accompanied by a refresher course.

The teachers are free to choose the teaching methods they follow, within the general perspective of the program. We clearly share the objectives for the end of the program where students are autonomous in dealing with the scientific literature and in participating to produce new results.

Example of a course

It is obviously not possible to describe the all courses of the training and it is not the object of this article. We want to highlight one course in particular which allows us to put forward the principle of training by project by mixing profiles. This is Methods4NLP given in unit 704. It is one of the very first courses introducing NLP to students. The teaching is divided into several sequences: a first one allowing to set up a common culture around NLP, a second academic one presenting the basic formalizations that they will develop throughout the two years of training, and the setting up of a project.

The first phase can be divided into three parts:

• a first phase of seminar to set the spectrum of NLP, from linguistic aspects to technical developments. This teaching allows to give a common culture to the students at the beginning of the program by positioning NLP in relation to the challenges of AI.

• a phase of apprehension of the concepts by experimentation with unplugged activities [START_REF] Bell | Computer science unplugged: School students doing real computing without computers[END_REF]) [START_REF] Romero | Analyse comparative d'une activité d'apprentissage de la programmation en mode branché et débranché[END_REF]: one simulating machine learning with a machine playing Nim's game, the other on Hoffman coding with groundhogs. The students meet the two paradigms of NLP in an intuitive way.

• first experiments to highlight the possibility of getting results with few developments with two labs: one on FastText [START_REF] Bojanowski | Enriching word vectors with subword information[END_REF]) [START_REF] Joulin | Bag of tricks for efficient text classification[END_REF] and theone on Sckitlearn [START_REF] Pedregosa | Scikit-learn: Machine learning in Python[END_REF], are proposed. The objective is to make all students aware of the ease of manipulating data without understanding what is behind it, and the difficulty of confronting how to improve the results.

The two other phases are carried out in parallel. For the project part, the students form groups of 4 in a balanced way between the profiles. It is requested that the students of the same nationality do not stay together and especially that all the groups have explicit different profiles (linguist and computer scientist). The groups choose the subject of their development. They are only required to explicitly include NLP aspects in their project (POS tagging, Named Entity recognition, Machine learning, etc.).

This project is shared with another course that deals with written corpora. For this course, the project must contain the constitution of a corpus, its normalization, as much as possible its annotation with study of the quality of the annotation, and thus implementation in a defined context. Thus, the themes of the projects are more naturally related to NPLP than to speech processing, or even to knowledge processing.

For information, here are a few topics chosen by the students: Gender bias in young targeted literature: 19th century vs. early 21st century, Author Identification for Philosophers, Song Lyrics Generator, Autonomous Vocabulary Assistant, ... It is interesting to let the students choose a topic that interests them. Sometimes we see students with very specific subjects, letting them work on them allows us to build on their engagement. If the subject is not relevant, it allows us to put them back into a more appropriate training perspective. There is no such thing as a bad topic. The different topics make students aware of the difference between the desire to achieve a development and the possibility of achieving it. In general, we see that some groups prefer to stay close to a very classical topic and often regret not having explored more diversity of topics. Moreover, a recurrent element appears on the question of the evaluation of development. This practice makes them aware of the significance of anticipating the implementation of the evaluation in order to measure the quality of the final project.

Students are monitored weekly. They have to make a 1 minute presentation of the progress of their developments in front of the whole class. They may not have made any progress, what is important is that all students follow the progress of all groups. During the Covid-19 period, the followup was done by videoconference and it was difficult to share this experience with the whole class. During the semester, students submit 3 progress reports, the first ones being only a few pages long. They are used to document problems, issues and progress. The final report is due before the exam period during which a defense is organized.

Finally, the last part consists of more academic teaching that takes up the two main paradigms of NLP and defines them explicitly [START_REF] Agarwal | Teaching the basics of NLP and ML in an introductory course to information science[END_REF]. The first part deals with out-of-context grammars and automata. These concepts are often known by students more or less well. This allows on the one hand to bring everyone up to speed and on the other hand to show how basic concepts in computer science find links with linguistics. This is done by looking at Turing's work on abstract machines, or through Chomsky's hierarchy. Then the course highlights the use of statistical techniques by explaining Bayes' models and automatic classification as done by Jurafsky [START_REF] Jurafsky | Speech and language processing[END_REF]. Finally, the last part explains dynamic programming by focusing on the syntax with the algorithm of CKY [START_REF] Dexter C Kozen | The cocke-kasami-younger algorithm[END_REF]. This part of the course is carried out in a traditional way with plenary teaching and tutorials. This teaching is the course which launches the training. Indeed, if it begins with a phase requiring little knowledge a priori, it continues with a phase that requires the mobilization of technical knowledge delivered in the other courses, as well as linguistic knowledge. The fact of leaving the choice of the theme allows to motivate the students, while showing them the need to be autonomous and proactive in the training. In addition, a very traditional part of the course allows students to establish common ground by building epistemological bridges between computer science and linguistics.

Analysis of student profiles

After having presented the structure, the organization and the stakes of the training, we propose to come back on quantitative elements concerning the disciplinary profile of the students, the diversity of their origin and their success. In order to give a little more perspective to these elements, we rely on the data of the Master since 2018, that is to say 3 academic years, as well as on the M2 TAL speciality over the 3 previous years.

Before the definition of the program, we had made a study on the 2008-2017 classes. We noted that 36% of the students were French, 45% from another European country and 19% from a non-European country, which is proof of a good diversity of origin. Of those who continued their studies after the course, 40% joined a company, 33% were doing a thesis and 27% had an academic post.

The table 1 presents the evolution of the number of candidates and students in the training before the creation of the Master (3 years) and for the first 3 years of the training. It also contains the distribution of students according to the profiles (Fosler-Lussier, 2008): computer science, mixed or linguistics. We observe that the distribution is homogeneous over the different years of training, with an average of 41.6% computer scientists over the first three years of the Master's program for 33.5% linguists. This good distribution makes it possible to build balanced work groups. Moreover, we observe that the opening as a Master has significantly increased the average number of this profile from 27 to 33.5. This implies reinforcing the course for this type of profile and increasing the means implemented on their programming skills.

Another interesting element that appears in this table is the increase in the number of candidates, with 117 candidates for the M1 year in 2020-21. It should be noted that this number of applicants does not include students trained within the IDMC or Erasmus Mundus LCT students who are selected through another process. For M2 students, only a few students are selected, the majority coming from the first year of training. Our experience leads us to limit even more the number of students entering the second year directly, because on the one hand these students have gaps that they are unable to fill, and on the other hand they have difficulties integrating the class. These elements must of course be put into perspective because the effects of the health crisis must also be taken into account.

Finally, the other axis of analysis proposed is to look at the nationalities of the students. It can be seen that the average number of French students has decreased significantly, from 44% to 34.5%. This decrease did not affect the rate of oversea students, keeping their number slightly above 50.

Finally, an important element is to analyze the profiles at entry with the success at the end of the Master's degree. The first element is that the students who follow the two years of training have better results and rankings. This supports the idea that the training has singular characteristics that are difficult to catch up on. This is understandable because it is necessary to master concepts in computer science and linguistics, and moreover it is necessary to master the tools and methods of AI, which are characteristic and rather abstract.

One should not believe that a profile at the entrance would be privileged in this type of training. The ringleader or the first ones of the promotions do not have a priori determined profiles. They may come from traditional computer science or linguistics. What seems to make the difference is, in addition to their aptitude at entry, their investment in the training throughout the two years. This reassures us that the aim is to bring together the profiles, while respecting their original specificities.

Conclusion and perspectives

We highlighted the process of creating the Master's degree in NLP at the IDMC. This training is unique in that it delivers a French diploma in NLP. The students who enter the program have a background either in computer science or in linguistics. The training aims to give them strong skills to train future professionals in language data processing.

We have integrated collaboration with several components in our environment (Erasmus Mundus LCT, EMLEX, Ecole des Mines, etc.). The training is attractive and has good results. The students trained in this way are currently making choices for their careers rather than being affected by the economic situation, despite the health crisis.

Over the number of internship proposals on the one hand and job offers on the other hand are constantly increasing. We see the search for profiles explicitly in NLP. Moreover, our opening towards more applied profiles has not been at the expense of the relationship with the academic world. Out of the first class that followed the 2 years of the training, 7 are pursuing a thesis which is very positive. These two dynamics reinforce our commitment to the development of the program.

For the future, we want to consolidate the training by slightly increasing the flow of students until we reach 40 students per year, especially with students from the European area. In addition, we are working on developping an alternation for research, which would allow us to offer training courses of very good quality towards PhD.

  2009, Maxime Amblard took over the responsibility of the Master's program on Cognitive Sciences (SC), institutionalizing the existence of the NLP theme in the university. From that moment on, he has been in charge of the NLP theme, first as head of the SC Master's program from 2009 to 2012 9 , and then as head of the M2 TAL 10 speciality from 2010 to 2012 and from 2015 to 2018. He carried out two years of sabatical leave 11 fully dedicated to research.He was then the project leader for the creation of the Master's program in NLP that was opened in 2018. He was the creator and organizor of the teaching from 2009 to today, both in Cognitive Sciences and in NLP. The responsibilities of 2nd year of the NLP program were assumed by Fabienne Venant in 2009-2010, Laure Buhry in 2013-14, then Miguel Couceiro from 2018. The coordination of the Erasmus Mundus LCT was carried by Miguel Couceiro since 2015.

Table 1 :

 1 the different years observed, we note that # applic. # students Comp. Mixed ling Distribution of students in the training over the last 6 years: number of candidates, number of students, then distribution of students in percentage (%) between the 3 profiles, then according to their nationality.

	Fr	Eu	World

Natural Language Processing

Institut des Sciences du Digital, du Management et de la Cognition https://idmc.univ-lorraine.fr/

https://idmc.univ-lorraine.fr/idmc-master-degree-innatural-language-processing/ history, we present the approach explaining the constitution of the program, then we return to the program itself. Finally we put forward some elements of analysis.

https://www.loria.fr/en/

https://www.atilf.fr//

Centre National pour la Recerhche Scientifique https://www.cnrs.fr/

Institut National de la Recherche en Informatique et Automatique https://inria.fr/

https://lct-master.org/

The responsibility of the SC master has since been assumed by Manuel Rebuschi

10 "Traitement automatique des langues" that then became NLP.

https://www.emlex.phil.fau.eu/


P Kervella

P Fouqué

The angular sizes of dwarf stars and subgiants (Research Note) Non-linear surface brightness relations in BV R c I c from interferometry

Keywords: Stars, fundamental parameters, Techniques, interferometric

The angular sizes of dwarf stars and subgiants -Non-linear surface brightness relations in BVRcIc from interferometry

Pierre Kervella, Pascal Fouqué

Introduction

The surface brightness-color (hereafter SBC) relations link the emerging flux per solid angle unit of a light-emitting body to its color. They express the Stefan-Boltzmann relation between total brightness and effective temperature in measurable quantities such as angular diameter, magnitude and color. It basically assumes that temperature and bolometric correction can be translated into a color measurement. These relations have many astrophysical applications, such as the estimation of Cepheid distances (through the Baade-Wesselink method), extrasolar planet transit studies or the characterization of microlensing sources. Different colors produce tighter or more dispersed relations, simply because color also depends on other variables such as gravity or metallicity, at a different level depending on the adopted photometric bands. It has been shown that a combination of visible and near-IR bands, such as (V -K), is probably optimal (see, e.g., Fouqué & Gieren 1997, in the case of Cepheids). However, nearinfrared photometry is not always available, for instance due to catalogue incompleteness or field crowding of IR atlases such as 2MASS in the Galactic disk. As a consequence, SBC relations in the visible domain remain very useful.

Although they are relatively similar for stars of different luminosity classes, the literature gives appropriate relations for Cepheids (Kervella et al. 2004c), giants (van Belle 1999, Nordgren et al. 2002), M giants and supergiants (van Belle et al. 1999, Groenewegen 2004), and dwarf or subgiant stars Send offprint requests to: P. Kervella Correspondence to: Pierre.Kervella@obspm.fr (Kervella et al. 2004b, hereafter K04). Here we limit our discussion to dwarf stars and subgiants, and revise and extend K04's work, which was based on Johnson photometric bands and was limited to linear SBC relations. In the present Note, we calibrate the SBC relations based on Cousins R c and I c photometric bands, of more common use than Johnson's R and I, and we adjust non-linear SBC relations that are a better fit to the observations than linear laws. In this process, we use exclusively direct interferometric angular diameter measurements, thus avoiding cross-correlations with previously calibrated SBC relations.

Interferometric and photometric data

We collected from the literature all the available interferometric angular diameter measurements of dwarf and subgiant stars. From this list, we removed the stars for which the angular diameter was uncertain by more than 5%. The major sets of new interferometric measurements of dwarf and subgiant stars since K04 are from Berger et al. (2006), Baines et al. (2008), Boyajian et al. (2008) and Kervella et al. (2008), all four based on measurements obtained with the CHARA array (ten Brummelaar et al. 2005). The only star from Berger et al. (2006) that has an angular diameter more precise than 5%, GJ 15A, was removed from our list as it is a flare star, and its photometry is therefore uncertain. This was also the case for several other M dwarfs. Most of the candidate stars present variability at a certain level. In order to reject those stars for which the variability amplitude could be large, we checked their variability status in the GCPD (Mermilliod et al. 1997) and the GCVS (Samus 2008). All stars listed in "γ Cas" or "UV Ceti" classes have been rejected. Low amplitude "δ Scuti", such as α Lyr or β Leo, "BY Dra" like ǫ Eri, GJ 570 A, GJ 699, 61 Cyg A, HR 511, or possible "RS Cvn", such as δ Eri, have been kept. As a remark, DY Eri (a "UV Ceti" type flare star) is not GJ 166 A, as stated in the SIMBAD database, but GJ 166 C, therefore we kept the former in our list. We also removed the known very fast rotating stars (v sin i 100 km.s -1 ), including the pole-on rotator α Lyr (Aufdenberg et al. 2006;Peterson et al. 2006). The effective temperature of fast rotating stars is inhomogeneous over their apparent disk, they can be surrounded by circumstellar material (Kervella & Domiciano de Souza 2006) and their photospheres can be spectacularly distorted (Monnier et al. 2007). All these phenomena combine to bias their surface brightness compared to normal stars. Overall, our selection procedure resulted in the removal of about one third of the available interferometric measurements (Table 1).

The limb darkened (LD) angular diameters were available in all cases from the original publication, except the measurementd of Sirius by Hanbury Brown et al. (1974) and Davis & Tango (1986), for which we applied the LD correction by Claret (2000), as discussed in Sect. 5.4 of Kervella et al. (2004a). For Mozurkewich et al.'s (2003) measurements we considered the combined LD values listed by these authors. In all cases, we chose to keep the original LD values instead of correcting the uniform disk values by recomputing the limb darkening corrections, because there is a remarkable concensus in the literature to use the predictions from Kurucz's atmosphere models, approximated using Claret's laws (Claret et al. 1995;Claret 2000;Claret 2000) to estimate the brightness distribution over the stellar disk. In fact, all the listed angular diameters were computed using these LD models, except the recent measurement of α Cen B published by Bigot et al. (2006) who employed 3D hydrodynamical models. Even in this case, the derived angular diameter was less than 1σ away from the 1D Kurucz model result. Claret (2008) recently showed that theoretical atmosphere models do not perfectly reproduce the observed stellar intensity profiles from transiting exoplanets and eclipsing binaries. However, these discrepancies are negligible for our purpose, considering the star-to-star residual dispersion with respect to the adjusted empirical laws (Sect. 3).

The starting point for the photometry listed in Table 2 is the Hipparcos Input Catalogue (1993) as retrieved from SIMBAD, which lists V and B-V, and the Hipparcos and Tycho Catalogues (1997), which list V -I. Notes in these catalogues give the origin of the listed values. When original photometry in Cousins system exists for V -R c and V -I c , it was checked from the on-line version of the Lausanne General Catalogue of Photometric Data (1997), averaged over original sources according to their number of measurements, and finally combined to the V band Hipparcos photometry to get R c and I c magnitudes. More details are given in the Notes of Table 2.

Surface brightness-color relations

Contrary to visible-infrared colors from K04, the dependence of the zero-magnitude limb-darkened angular diameter (ZMLD, defined for m λ = 0), as a function of the color is non linear in the visible. For this reason, we selected polynomial SBC relation models of the form:

log(θ LD ) = a 0 + a 1 C + a 2 C 2 + a 3 C 3 + a 4 C 4 -0.2 m λ (1)
where C is the color of the star from two dereddened photometric bands among BVR c I c (e.g. B -V, V -R c ,...), m λ the dereddened magnitude of the star in one of the bands, and θ LD the limbdarkened angular diameter, measured in milliarcseconds (mas).

Note that this expression is independent of the distance of the star. For the empirical fit to the observations, we selected the smallest polynome degree that gave a satisfactory fit of all the data points. This led us to select a higher degree (four) for the B -V based polynomial fits. We would like to stress that the computed relations are valid only for a given range of colors, with only little margin for extrapolation. In particular, the SBC laws undergo steep variations for red objects. The results of the fits are presented in Fig. 1 for 3. The residual dispersions σ(θ LD )/θ LD give the relative accuracy of the angular diameter predictions for each relation.

Discussion

Reddening corrections and metallicity

When a SBC relation is applied to a star suffering some amount of absorption, its colors must be corrected for extinction before applying the relation. The amount of extinction is generally measured by the color excess E(B -V), and the conversion to other photometric bands depends on the intrinsic color of the star and on the amount of extinction (Dean et al. 1978). For blue stars, the color excess ratios are typically 3.

E(V -R c ) = 0.60 E(B -V)
and E(V -I c ) = 1.25 E(B-V). For red stars, the coefficients may increase by up to 10%. All the stars in our list are very nearby. In average, we do not expect a significant deviation of their metallicity compared to that of the Sun. The exoplanet stars observed by Baines et al. (2008) probably present a slight overmetallicity, but the effect on the dispersion of the adjusted SBC relations is taken into account in the dispersions stated in Table 3. As discussed by K04, the effect of metallicity on the visible-infrared SBC relations is undetectable. For the visible SBC relations presented here, different metallicities will translate into more significant photometric color differences. However, we expect them to be small compared to the measured intrinsic dispersion of the relations, at least over a ±0.5 dex range around solar metallicity.

Application to transits and microlensing

The existence of exoplanetary transits in front of a star allows to retrieve its linear radius, as well as the planetary radius. However, when the parallax is not known accurately and/or the star is too faint for high accuracy angular velocity measurements (from high resolution spectroscopy), they are based on an a priori radius for the star. The relations established in the present Research Note are useful in this context, as they allow to retrieve Table 3. Polynomial coefficients of the adjusted surface brightness-color relations: log(θ LD ) = a 0 +a 1 C+a 2 C 2 +a 3 C 3 +a 4 C 4 -0.2 m λ (θ LD expressed in milliarcseconds). N is the number of measurements used for the calibration. The listed C min and C max values correspond to the minimum and maximum color index of the stars included in the polynomial fitting procedure. They represent the limits outside of which the adjusted relations are unreliable and should not be employed. The standard deviation of the residuals of the fit in log scale is listed in the σ(log θ LD ) column, and the corresponding relative uncertainties on the predicted angular diameter is given in the rightmost column, in percentage. Due to the proximity of this star, we neglect the reddening. For these bands, the surface brightness relation is (Table 3):

λ C N C min C max a 0 a 1 a 2 a 3 a 4 σ(log θ LD ) σ(θ LD )/θ LD B B -V 42 0.
log(θ LD ) = 0.4992 + 0.6895 (V -I c ) -0.0657 (V -I c ) 2 -0.2 V(2)
and we obtain θ LD (HD189733) = 0.352 ± 0.020 mas. The attached 6% uncertainty contains the photometric uncertainties and the intrinsic dispersion of the (V, V -I c ) relation. Together with the Hipparcos parallax of this star π = 51.94 ± 0.87 mas, we obtain a linear photospheric radius of 0.728 ± 0.044 R ⊙ . This is in excellent agreement with the radius derived from HS T transit observations by Pont et al. (2007) of 0.755 ± 0.011 R ⊙ . We can also compare the (V, V -I c ) angular diameter to the one computed from the infrared (V, V -K) linear relations calibrated by K04. The 2MASS catalogue (Skrutskie et al. 2006) lists K = 5.541 ±0.021, giving θ LD (HD189733) = 0.372 ±0.007 mas. Although this value is within 1σ of the (V, V -I c ) value, the uncertainty on this visible-infrared prediction is only one third of the visible version. A complete review of the properties of this system can be found in Torres, Winn & Holman (2008).

Another important application of SBC relations is related to gravitational microlensing studies, when one needs to estimate the source radius from color-magnitude diagram (CMD) in the direction of the Galactic Bulge. Deredenned source magnitude and color are obtained from the relative position of the source in a CMD, with respect to the mean position of the Red Giant Clump (RGC). As the intrinsic position of the RGC is calibrated from nearby stars by Hipparcos, the assumption that the source suffers the same amount of extinction as the clump avoids the need for an estimate of the extinction (see Yoo et al. 2004 for details). Generally, the magnitudes are measured in the I c band, and the measured color is (V -I c ), because this is what OGLE measures. A caveat of K04's SBC relations is that they are attached to the Johnson R and I bands, and this has been a source of confusion in the past. Let's take the example of the recently discovered 3 Earth mass planet event MOA-2007-BLG-192 (Bennett et al. 2008). The source appears to be fainter than the RGC by 5.7 mag in I c , and redder by 0.07 mag in (V -I c ). At the source distance (7.5 kpc), the RGC is at I c0 (RGC) = 14.13 and (V -I c ) 0 (RGC) = 1.04, so the source has I c0 (MOA 192) = 19.84 ± 0.24 and (V -I c ) 0 (MOA 192) = 1.11 ± 0.24 (see Bennett et al. 2008 for a detailed discussion of these values). Applying the appropriate (I c , V -I c ) SBC relation from Table 3 gives an estimated angular diameter of θ LD (MOA 192) = 0.99 ± 0.14 µas, which is resolved by the caustic crossing (or cusp approach).

Comparison with other calibrations

In their early publication, Barnes et al. (1978) obtained a linear SBC relation F V = 3.964 -0.333 (B -V) for 0.10 (B-V) 1.35, with a typical residual scatter of σ(F V ) = ±0.025. Following K04, it can be expressed as log(θ LD ) = 0.5134 + 0.666 (B -V) -0.2 V with a scatter of σ(log θ LD ) = ±0.05, equivalent to σ(θ LD ) = ±12%. Over their common range of applicability, the relative difference ρ in θ LD with our polynomial relation (coefficients listed in Table 3) is ρ(B78) = [θ LD (B78) -θ LD (K08)] /θ LD (K08) = 3.6 ± 3.5%. (3)

We can also compare our (B, B -I) predictions (as an example) with the (V, V -K) relations calibrated recently by Beuermann (2006, hereafter B06). The S V (V -K) relation of this author's Table 2 can be reformulated as: log θ LD = 0.524 (V -K) 2 + 0.267 (V -K) -1.221 10 -3 -0.2 V(4)

For the 34 stars in our sample, we obtain an average value of the relative difference with our calibration of ρ(B06) = 4.1 ± 5.2%. One should note that B06's calibration relies on several data sources, including indirect angular diameter estimates. The same comparison with K04's (V, V -K) relation gives ρ(K04) = 0.7±4.6%. The present calibration of the visible SBC relations is therefore compatible with previously determined SBC relations using visible and visible-IR color indices.

Conclusion

We computed polynomial SBC relations in BVR c I c that can be used to predict the angular size of individual stars for which only broadband photometry is available. The visible-infrared linear relations established by K04 usually provide more accurate angular size estimates. However, in many cases the JHK band magnitudes of field stars are not available (due to crowding in 2MASS for instance), and the present BVR c I c relations will provide a reliable photospheric angular diameter prediction with a typical uncertainty of ≈ 5%. Their compatibility with visible-IR relations gives further confidence in their accuracy.

  (a) Bessell 1990; (b) Cousins 1980b; (c) Cousins 1980a; (d) Celis 1986; (e) Thé 1984; (f) Laing 1989; (S) Holmberg et al. 2006; (C) Hipparcos catalogue, Field H42 = C (C*) for 61 Cyg A and B, we transformed (V -I) j from Ducati (2002) to (V -I) c according to Hipparcos precepts when Field H42 = C (F) Hipparcos catalogue, Field H42 = F (F*) for 55 Cnc, we converted (R -I) c = 0.388 ± 0.003 from Taylor (2003) to (V -I) c according to Hipparcos precepts when Field H42 = F (G) Hipparcos catalogue, Field H42 = G (H) Hipparcos catalogue, Field H42 = H (I*) for GJ380, we converted (B -V) t from Tycho to (V -I) c according to Hipparcos precepts when Field H42 = I B and V and in Fig. 2 for R c and I c . The polynomial coefficients and the domain of validity of each relation, are listed in Table

Fig. 1 .

 1 Fig. 1. Adjusted polynomial relations giving the zero-magnitude limb-darkened disk angular diameter (ZMLD λ ) in the B and V bands as a function of different color combinations. The corresponding polynomial coefficients are listed in Table3.

Fig. 2 .

 2 Fig. 2. Adjusted polynomial relations in the R c and I c bands.

Table 1 .

 1 Interferometric data. The error bars are listed in small characters as exponents.

	Star	Spect.	λ θ UD (mas)	θ LD (mas) Ref.
	α CMa A	A1V	B 5.600 0.070	5.896 0.074	1
	α CMa A	A1V	B 5.630 0.080	5.928 0.084	2
	α CMa A	A1V	K 5.936 0.016	6.039 0.019	3
	α CMa A	A1V	V	5.993 0.108	4
	α PsA	A3V	K 2.197 0.023	2.228 0.023	5
	β Leo	A3V	K 1.429 0.027	1.449 0.027	5
	94 Cet	F8V	K 0.774 0.026	0.788 0.026	6
	α CMi A	F5IV-V	V 5.190 0.040	5.430 0.070	7
	α CMi A	F5IV-V	V	5.446 0.054	4
	α CMi A	F5IV-V	K 5.376 0.047	5.448 0.053	8
	τ Boo	F7V	K 0.771 0.015	0.786 0.016	6
	υ And	F8V	K 1.091 0.009	1.114 0.009	6
	η Boo	G0IV	V 2.170 0.060	2.280 0.070	7
	η Boo	G0IV	V	2.269 0.025	4
	η Boo	G0IV	K	2.200 0.031	9
	µ Her	G5IV	V	1.953 0.039	4
	ζ Her A	G0IV	V	2.367 0.051	4
	ζ Her A	G0IV	V 2.370 0.080	2.490 0.090	7
	α Cen A	G2V	K 8.314 0.016	8.511 0.020	10
	Sun	G2V		1919260 10
	70 Vir	G5V	K 0.986 0.023	1.009 0.024	6
	µ Cas A	G5Vp	K 0.951 0.009	0.973 0.009	11
	HR 7670	G6IV	K 0.682 0.019	0.698 0.019	6
	55 Cnc	G8V	K 0.834 0.024	0.854 0.024	6
	β Aql	G8IV	V 2.070 0.090	2.180 0.090	12
	τ Cet	G8V	K 2.032 0.031	2.078 0.031	5
	54 Psc	K0V	K 0.773 0.026	0.790 0.027	6
	σ Dra	K0V	K 1.224 0.011	1.254 0.012	11
	HR 511	K0V	K 0.747 0.021	0.763 0.021	11
	δ Eri	K0IV	K	2.394 0.029	9
	η Cep	K0IV	V 2.510 0.040	2.650 0.040	12
	α Cen B	K1V	K 5.881 0.021	6.000 0.021	13
	GJ 166A	K1V	K 1.600 0.060	1.650 0.060	14
	ǫ Eri	K2V	K 2.093 0.029	2.148 0.029	5
	GJ 570A	K4V	K 1.190 0.030	1.230 0.030	14
	GJ 845	K4.5V	K 1.840 0.020	1.890 0.020	14
	61 Cyg A	K5V	K	1.775 0.013	15
	61 Cyg B	K7V	K	1.581 0.022	15
	GJ 380	K7V	HK 1.268 0.040	1.175 0.040	16
	GJ 887	M0.5V	K 1.366 0.040	1.388 0.040	17
	GJ 411	M1.5V HK 1.413 0.030	1.464 0.030	16
	GJ 699	M4Ve	HK 0.987 0.040	1.026 0.040	16
	References: (1) Hanbury Brown et al. 1974; (2) Davis & Tango 1986.
	(3) Kervella et al. 2003a; (4) Mozurkewich et al. 2003; (5) Di Folco et
	al. 2004; (6) Baines et al. 2008; (7) Nordgren et al. 2001; (8) Kervella
	et al. 2004a; (9) Thévenin et al. 2005; (10) Kervella et al. 2003b; (11)
	Boyajian et al. 2008. (12) Nordgren et al. 1999; (13) Bigot et al. 2006;
	(14) Kervella et al. 2004b; (15) Kervella et al. 2008; (16) Lane et
	al. 2001; (17) Ségransan et al. 2003;

Table 2 .

 2 Photometric data. When the uncertainty on the photometric measurements was not available, we adopted an arbitrary ±0.05 value.

	Star	B	V	R c	I c	Ref.
	α CMa A	-1.43 0.01	-1.44 0.01	-1.43 0.05	-1.42 0.05	ab
	α PsA	1.25 0.02	1.17 0.02	1.11 0.05	1.09 0.05	bc
	β Leo	2.23 0.01	2.14 0.01		2.04 0.05	H
	94 Cet	5.65 0.01	5.07 0.01	4.75 0.05	4.44 0.05	c
	α CMi A	0.83 0.03	0.40 0.03	0.15 0.06	-0.09 0.06	bc
	τ Boo	5.00 0.03	4.49 0.03		3.98 0.04	C
	υ And	4.63 0.01	4.09 0.01		3.51 0.03	C
	η Boo	3.26 0.01	2.68 0.01		2.03 0.05	H
	µ Her	4.16 0.03	3.41 0.03		2.70 0.04	G
	ζ Her A	3.46 0.01	2.81 0.01		2.11 0.03	G
	α Cen A	0.70 0.05	-0.01 0.03	-0.37 0.06	-0.70 0.06	a
	Sun	-26.11 0.02 -26.75 0.01 -27.10 0.01 -27.44 0.01	S
	70 Vir	5.69 0.01	4.98 0.01		4.21 0.05	G
	µ Cas A	5.87 0.03	5.17 0.03		4.34 0.04	G
	HR 7670	6.50 0.01	5.75 0.01		4.92 0.07	F
	55 Cnc	6.83 0.02	5.96 0.01		5.13 0.07	F*
	β Aql	4.57 0.01	3.72 0.01	3.26 0.05	2.83 0.05	bc
	τ Cet	4.22 0.01	3.50 0.01	3.07 0.05	2.68 0.05	bc
	54 Psc	6.73 0.02	5.88 0.02		5.05 0.02	G
	σ Dra	5.46 0.01	4.68 0.01		3.83 0.02	G
	HR 511	6.43 0.01	5.63 0.01		4.82 0.05	G
	δ Eri	4.44 0.02	3.53 0.01	3.02 0.05	2.59 0.05	bc
	η Cep	4.34 0.01	3.43 0.01		2.49 0.04	G
	α Cen B	2.25 0.04	1.35 0.03	0.88 0.06	0.47 0.06	a
	GJ 166A	5.25 0.01	4.43 0.01	3.96 0.05	3.54 0.05	bc
	ǫ Eri	4.61 0.01	3.73 0.01	3.22 0.05	2.78 0.05	bc
	GJ 570A	6.75 0.03	5.72 0.03	5.07 0.06	4.54 0.06	d
	GJ 845	5.74 0.02	4.69 0.01	4.06 0.05	3.54 0.05	bcd
	61 Cyg A	6.27 0.03	5.20 0.03		3.89 0.04	C*
	61 Cyg B	7.41 0.03	6.06 0.02		4.50 0.04	C*
	GJ 380	7.97 0.02	6.60 0.01		5.09 0.02	I*
	GJ 887	8.83 0.01	7.35 0.01	6.38 0.05	5.33 0.05	ce
	GJ 411	9.00 0.02	7.50 0.01	6.49 0.05	5.35 0.05	d
	GJ 699	11.11 0.03	9.54 0.03	8.31 0.06	6.76 0.06	acdf
	References:

Acknowledgements. This research made use of the SIMBAD and VIZIER databases at the CDS (Strasbourg, France), the Hipparcos catalogues, the Lausanne General Catalogue of Photometric Data, the General Catalogue of Variable Stars, and NASA's ADS Bibliographic Services. We also received the support of PHASE, the high angular resolution partnership between ONERA, Observatoire de Paris, CNRS, and University Denis Diderot Paris 7.