Sylvain Kahane

Bernard Caron

Emmett Strickland

Kim Gerdes

Annotation guidelines of UD and SUD treebanks for spoken corpora: a proposal

This paper presents practical and theoretical guidelines for the development of treebanks for spoken languages in the UD and SUD annotation schemes. We discuss text-sound alignment, segmentation into "sentences", use of "punctuation", paradigmatic lists, disfluencies, and paratactic constructions. This proposal is based on the development of (Surface-Syntactic) Universal Dependencies treebanks for spoken French, Naija, and Beja.

Introduction

This paper presents our recommendations for the development of treebanks for spoken languages, based on our experience in the development of several treebanks for spoken French [START_REF] Gerdes | Speaking in piles: Paradigmatic annotation of French spoken corpus[END_REF], Lacheret et al. 2014[START_REF] Batchelor | Universal dependencies for Scottish Gaelic: syntax[END_REF], Cantonese [START_REF] Wong | Quantitative comparative syntax on the Cantonese-Mandarin parallel dependency treebank[END_REF], and more recently a large treebank for spoken Naija, an English-lexifier pidgincreole from Nigeria which is spoken by more than 100 million people [START_REF] Caron | A Surface-Syntactic UD Treebank for Naija[END_REF], as well as a small treebank for Beja, an Afro-Asiatic language spoken in Sudan [START_REF] Kahane | A morph-based and a word-based treebank for Beja[END_REF]. All of these treebanks are dependency-based, and our more recent treebanks use the SUD (Surface-Syntactic Universal Dependencies) framework [START_REF] Gerdes | SUD or Surface-Syntactic Universal Dependencies: An annotation scheme near-isomorphic to UD[END_REF][START_REF] Gerdes | Improving Surface-syntactic Universal Dependencies (SUD): surface-syntactic functions and deep-syntactic features[END_REF](Gerdes et al. , 2021)), which can be automatically converted into UD (Universal Dependencies) (de [START_REF] De Marneffe | Universal Dependencies[END_REF]. Previous attempts to provide guidelines for UD-based spoken treebanks include [START_REF] Dobrovoljc | The Universal Dependencies treebank of spoken Slovenian[END_REF] and Øvrelid et al. (2018).

The need for special guidelines for spoken language treebanks arises from several particularities of spoken language corpora and spoken language grammar.

Spoken corpora are transcriptions of audio and video recordings. We will not discuss the issue of these transcriptions, as conventions can vary from language to language. 1 However, the relationship between the written text and the sound file which characterizes oral corpora introduces some specificities in the treebank itself, which are discussed in Section 2. The identification of speakers and the marking of overlaps between speakers are also considered.

The next challenge in the transcription of spoken languages is the fact that recorded speech does not contain any consistent sentence boundaries. A segmentation based on prosody is sometimes adopted, especially for interlinear glossed texts (IGTs), but prosodic units can be strongly divergent from syntactic units [START_REF] Beliao | Interface intono-syntaxique en français parlé : compter quoi, compter comment, compter pourquoi ?[END_REF][START_REF] Kahane | Syntax and prosody mapping: What and how? The case of intonational periods and illocutionary units[END_REF]. Section 3 is devoted to segmenting 1 Each language we considered is bound by different constraints. French has a strong tradition of orthographic normalization (even if there remains some room for discussion, see [START_REF] Dister | Orthographic and phonetic transcriptions of Rhapsodie recording[END_REF]. Naija orthography has yet to be codified, even if the language now enjoys some official written media presence through outlets like BBC News Pidgin (https://www.bbc.com/pidgin). We therefore gave our transcriptors the freedom to choose how best to represent the language in writing. Beja has no written tradition whatsoever, which means that our Beja corpus is an interlinear glossed text with a phonetic transcription and a word segmentation done by a linguist [START_REF] Vanhove | The Beja Corpus[END_REF].

spoken texts into maximal syntactic units. Following the French tradition of studies of the syntax of spoken French (Blanche-Benveniste 1990, Berrendoner 1990), we consider two levels of analysis, referred to as microsyntax and macrosyntax in the French scholarly tradition: microsyntax, which is the syntax of government (Fr. rection), describes marked relations where one word imposes its form, category, or position on another; macrosyntax concerns looser relations, such as those involving detached/dislocated units, parentheses, inserts, discourse markers, etc. Macrosyntactic units generally correspond to units that are delimited by punctuation in written texts. The choice of the delimiters also requires some discussion.

One particularity of spoken productions is the great number of paradigmatic lists or "piles", which are successions of units piled up in the same syntactic position. This is the case with coordination, but also reformulation, or apposition. Section 4 proposes a homogeneous treatment of these constructions.

Section 5 is devoted to the analysis of disfluencies due to incomplete units.

The last characteristic of spoken languages we examine is the variety of paratactic constructions used in spoken production. In Section 6 we propose splitting the parataxis relation of UD into seven different subtypes.

Text-sound alignment and speech turns

UD-based treebanks are encoded using the CoNLL-U format (https://universaldependencies.org/ format.html). In this tabular format, each sentence is encoded separately. Each token occupies a row and information associated with that token is divided into 10 columns (see Fig. 1).2 Metadata associated with a given sentence precede the table describing the dependency tree. These metadata must contain the text of the sentence (# text) and a sentence id (# sent_id). For spoken corpora, two main pieces of information should be added: a (permanent) link to the sound file (# sound_url) and, if the corpus is not a monologue, an id for each speaker (# speaker_id). With the sound url and an additional temporal alignment, it is possible to listen to the sound associated with each word. In (S)UD_Naija-NSC and in (S)UD_Beja-NSC, each word is time-aligned using the features AlignBegin and AlignEnd, with a value in milliseconds from the start of the sound file. 3 If the corpus features punctuation marks, the two features should typically be equal in value unless the symbol corresponds to a prosodic break. These word-level features also allow one to determine the timespan of a given utterance: the AlignBegin value of the first token correspond to the beginning of the utterance, while the AlignEnd value of the final token corresponds to the end. For corpora with only a sentence-level alignment, we recommend adding a single AlignBegin feature to the first token, and an AlignEnd feature to the last.

For the time being, (S)UD_Naija-NSC, (S)UD_Beja-NSC, and (S)UD_French-ParisStories are the only (S)UD treebanks that provide a link towards a sound file. UD_English-GUM (Zeldes 2017), a third of which represents spoken data, contains # speaker and # addressee features, which are, to our knowledge, the only way to distinguish spoken from written utterances. UD_Polish-LFG [START_REF] Patejuk | From Lexical Functional Grammar to Enhanced Universal Dependencies: Linguistically informed treebanks of Polish[END_REF]) contains a feature # genre = spoken (prepared) to distinguish the spoken data. UD_Frisian_Dutch-Fame (Braggaar & Vander Goot 2021) and UD_Scottish_Gaelic-ARCOSG [START_REF] Batchelor | Universal dependencies for Scottish Gaelic: syntax[END_REF]) have a # speaker feature, while UD_Norwegian-NynorskLIA (Øvrelid et al. 2018) has metadata including compound features like # dialect: eidsberg speakerid: eidsberg_uio_03, which include both a location and a speaker id. UD_Latvian-LVTB [START_REF] Pretkalniņa | Deriving enhanced Universal Dependencies from a hybrid dependency-constituency treebank[END_REF]) has a feature # newpar id, which probably contains the speaker id of new participant. Other treebanks of spoken languages (UD_Turkish_German-SAGT, UD_Slovenian-SST, UD_Cantonese-HK, UD_Komi_ Zyrian-IKPD, UD_Swedish_Sign_Language-SSLC, UD_Chukchi-HSE)4 do not contain any specific metadata, while some treebanks (UD_English-Lines, UD_Greek-GDT, UD_Persian-Seraji) that are partially composed of spoken data do not contain any metadata allowing one to distinguish between speech and writing. For mixed corpora, we think that a feature # genre = spoken should be used to facilitate the identification of speech. Outside of (S)UD, the CHAT transcription system used in the CHILDES database of childhood speech marks each utterance with a three-letter speaker identifier, each of which is associated with a name and role (i.e., father, mother, child) in the file header. Additional information may be provided about a speaker's background (age, socioeconomic status) and the context of the recording, while special punctuation can be used to designate overlapping speech [START_REF] Macwhinney | The CHILDES Project: Tools for Analyzing Talk. 3rd Edition[END_REF].

Note that in (S)UD corpora only one speaker and one # speaker_id is allowed for each utterance. In instances of co-constructions between two speakers, we use the special features AttachTo and Rel. By co-constructions, we mean two trees T1 and T2 from two different speakers that form a cohesive syntactic construction, as in (1) from SUD_French-Rhapsodie.5

(1) $L3 ^et c'est récupéré ( bien sûr ) par l'équipe $-argentine //+ $L2 qui -$ sont de nouveau en possession ( les Argentins ) du "euh" ballon // '$L3 ^and it is recovered ( of course ) by the $-Argentinian team //+. $L2 who -$ are again in possession ( the Argentines ) of the "uh" ball //' One token from T1 is the governor of the root of T2 in this new construction. In (1), L2's utterance is a relative clause that modifies the noun équipe 'team' from L3's utterance. This is indicated on the root of the second tree by the feature AttachTo=11@Rhap_D2003-92bis indicating that this utterance could be attached to the 11th token of tree Rhap_D2003-92bis, and by the feature Rel=mod@relcl indicating the relation between the two tokens (see Fig. 2 and3). 6 # macrosyntax = ^et c'est récupéré ( bien sûr ) par l'équipe $-argentine //+ # text_ortho = et c'est récupéré, bien sûr, par l'équipe, euh, argentine. In cases of overlap between two speech turns, words that overlap have a feature Overlap whose value is the id of the overlapping sentence. In our previous example, argentine, of sentence Rhap_D2003-92bis, has a feature Overlap=Rhap_D2003-92ter, indicating that it overlaps with sentence Rhap_D2003-92ter, more specifically with the word qui 'who', which itself carries the feature Overlap=Rhap_D2003-92bis. Overlaps can also be deduced from time alignment, but some corpora indicate overlaps without also containing temporal information, and for most query engines it is much simpler to request overlaps if a feature is present.

# speaker = L3 # sent_id = Rhap_D2003-92bis 1 et et CCONJ _ _ 3 cc _ _ 2 c' ce PRON _ Gender=Masc|Number=Sing|Person=3|PronType=Dem 3 subj@pass _ _ 3

Sentence segmentation and punctuation

With the exception of rehearsed speeches and other kinds of highly prepared oratory, oral language cannot typically be segmented into units equivalent to the written sentence. Instead, we segment our corpora into illocutionary units (IUs) [START_REF] Cresti | Speech act units and informational units[END_REF], Pietrandrea et al. 2014). An IU is defined as a speech segment that corresponds to a single speech act, i.e., a single question, declaration, or command. Consider the following examples from French and Naija.

(2) ceux qui sont en location < la moyenne < c'est environ trois ans // those who are on lease < the average < it is about three years // 'For those that rent, the average lease is about three years.' (3) e get one lady < hm she just enter inside shop o // there was one lady < hm she just came into the shop // These utterances represent cohesive linguistic units serving to express a single primary idea. One can split these into internal units sharing no marked relations of dependency with one another, separated in these examples by the character <. The cohesiveness of these units can nevertheless be demonstrated by their varying degrees of autonomy. For example, the utterances c'est environ trois ans 'it is about three years' and hm she just enter inside shop o 'hm she just came into the shop' form perfectly acceptable utterances in isolation that carry the same basic message as the original utterance. However, la moyenne 'the average' or e get one lady 'there was one lady' would either be unacceptable or serve a very different illocutionary purpose in isolation. In oral corpora, we recommend preserving this cohesiveness by using the IU as the primary unit of segmentation. Within each IU, internal components can be delimited through special symbols, either placed directly in the list of tokens, or in a dedicated sentence feature containing the macrosyntactic annotation (and replaced in the text by standard punctuation signs; see Note 5).

In our corpora, the end of each IU is marked by a symbol indicating an IU boundary. In the corresponding CoNLL-U file, these may be integrated directly into the list of tokens and annotated as punctuation marks. In order to better identify the modality of each IU, we recommend introducing a separate boundary marker for each type of utterance. In our corpus of spoken Naija, the symbol // is used to mark the end of an assertion, ?// the end of a question, and !// the end of an order or an exclamation. The symbol &// is used to mark the end of an interrupted or incomplete utterance. However, more traditional symbols such as periods and question marks may also be used so long as they are used consistently as IU boundary markers.

(4) I no pass all di subjects // 'I didn't pass all of the subjects.' (5) wetin be Ponzi Scheme ?// 'what is a Ponzi Scheme?' (6) listen attentively !// 'listen attentively!' (7) e get things wey you &// 'there are things that you…'

As demonstrated previously in examples ( 2) and (3), IUs can contain internal units with varying degrees of autonomy. All completed utterances must contain at least one (and typically only one) nucleus, a fully autonomous macrosyntactic unit capable of forming an acceptable utterance when spoken alone in the same discursive position [START_REF] Pietrandrea | Macrosyntactic annotation[END_REF]. Examples (4-6) are each composed of one nucleus, but IUs can also contain multiple adnuclei located to the left or right peripheries of the nucleus. These are illocutionarily dependent on the nucleus and typically lack any marked microsyntactic relationship with the elements of the nucleus. These can be divided into prenuclei, located to the left of the nucleus, and postnuclei, located to the right. Like the IU boundaries, we recommend explicitly delimiting these units using a dedicated set of symbols. In our corpora, we favor using < to mark the ends of prenuclei (see ex. 8-9) and > to mark the beginning of postnuclei (ex. 10-11). However, more traditional symbols such as commas may also be used.

(8) les chaises < il faut me les donner // 'the chairs, you need to give them to me.' (9) en ce qui me concerne < j'aimerais enseigner dans un établissement public // 'as for me < I would like to teach in a public school' (10) dat's what de use to do > some of dem o // 'that's what they used to do, some of them.' (11) good evening > my daughter // 'good evening, my daughter.'

Note that it is possible for an IU to contain strings of adnuclei ( 12) donc < alors < ça date de quand à peu près > ce fauteuil-là ?// 'so, then, it dates from when approximately, this armchair?' (13) Osas < dis your wedding wey you dey prepare < me < I dey look forward to di ting o !// 'Osas, that wedding of yours that you are preparing, me, I'm looking forward to it!'

These adnuclei are typically connected to the root of the utterance using the UD relations dislocated, vocative, discourse, and in some cases parataxis. These are discussed in Section 6. 7

It is important to note that our segmentation generally avoids coordination between main verbs in a single IU, since each part can form an autonomous utterance. ( 13) shows a string of consecutive IUs each containing a single main verb. ( 14) vous oubliez vos produits habituels.

et vous mettez à l'intérieur la boule magique, la boule de lavage avec vos vêtements. et vous allez voir le résultat. 'you forget your usual products. and you put inside the magic ball, the washing ball with your clothes. and you will see the result.'

Paradigmatic lists

The annotation of paradigmatic structures is challenging in any analysis that marks heads, such as dependency-and X-bar-based phrase structure, because the idea of paradigm itself supposes that two or more elements jointly qualify as the head of a phrase. SUD and UD use the same set of basic relations to encode paradigmatic structures: The conj and cc relations for standard coordination, the list relation that is absent from the analysis of spoken data that we propose, 8 and finally the orphan and reparandum relations used respectively for ellipsis and disfluency.

As shown in Blanche-Benveniste et al. (1990) and [START_REF] Gerdes | Speaking in piles: Paradigmatic annotation of French spoken corpus[END_REF], reformulation is hard to delimit on a spectrum from coordination to actual repairs, where a second phrase replaces the first. Are (15a) and (15b) coordinations or reformulations? (15) a. et puis après, ben, j'ai travaillé sur les micro-processeurs, l'informatique. 'and then, well, I worked on microprocessors, computers.' b. mais comme toujours, l'acte d'écrire peut prendre différents masques, différentes valeurs. (Rhap_2009-2) 'but as always, the act of writing can take on different masks, different values.'

7 Fillers uttered by the listener, such as Fr. mh 'hum', are considered discourse markers attaching to the speaker's utterance. They have their own tree but carry the features AttachTo and Rel=discourse.

8 list encodes a list containing only fragments such as address information or phone numbers.

Reformulations are not necessarily repairs but rather elaborations that are also frequently used by rhetorically skilled speakers.

( We excluded the reparandum relation from the analysis of spoken data in our SUD annotation scheme, and instead use the concept of paradigmatic lists developed by [START_REF] Blanche-Benveniste | Le français parlé (études grammaticales)[END_REF] and produce a simple typology of paradigmatic lists (Kahane & Pietrandrea 2012) by annotating three sub-relations of the conj dependency:

• conj:coord: the standard coordination, where each conjunct denotes a different referent;

• conj:dicto: used for several denotations of the same referent, which are repetitions or reformulations of the same denotation, as in ( 16), including disfluencies as in (16b); • conj:appos: used for double denotations of the same referent, as in (17). 9

We decided not to distinguish reformulation and disfluencies because the line between voluntary and unvoluntary reformulation or correction is very difficult to draw. 10 In the transfer to UD annotation, conj:dicto is renamed reparandum, even if it is not exactly a standard reparandum annotation, because the first conjunct remains the head. 'and it is in this spirit that Szymanoski proposes the opening of the concert, his opus twelve.' c. eh bien, le secret, il est là, dans ce petit bruit que l'on entend. (Rhap_D2011-57) 'well, the secret is there, in this small noise that we hear.'

In the case of a partial answer to a wh-question, we also consider that the answer forms a conj:appos pile with the wh-word, encoded using the AttachTo and Rel features. 9 UD uses the same appos relation for appositions that form paradigmatic lists and appositions where one unit modifies the other. We propose encoding the latter as a standard modification (mod in SUD or nmod in UD) or as subtype of modification (mod:appos in SUD or nmod:appos in UD) since the two constructions have different semantic and prosodic properties: in conj:appos, the two conjuncts are separate prosodic units, the apposed unit being in a different register, while in mod:appos, the two elements form one cohesive prosodic unit (my brother John, le journal Le Monde). 10 The initial Rhapsodie annotation considered seven different cases of paradigmatic lists (Kahane & Pietrandrea 2020). The distinction between disfluencies and reformulation was based on purely formal criteria (repetition of a unit) to avoid poor interannotator agreement [START_REF] Bawden | Correcting and Validating Syntactic Dependency in the Spoken French Treebank Rhapsodie[END_REF]).

11 The notion of reparandum presupposes that the second conjunct repairs the first [START_REF] Shriberg | Preliminaries to a theory of speech disfluencies[END_REF]. Following Blanche-Benveniste (1990), we instead consider that, in reformulations, even involuntary ones, information is cumulative, and nothing that has been said can be completely forgotten.

(18) $L1 Magalie utilise depuis combien de temps notre boule magique? $L5 depuis deux mois. '$L1 how long has Magalie been using our magic eight ball? $L5 for two months.'

Disfluencies

One kind of disfluency, often called repair, is observed when a unit, then called the reparandum, gets overridden by a new unit, the repair. As shown in section 4, this is a subtype of the common mechanism of listing, which is not necessarily disfluent and which we formalize with the relation conj:dicto.

Another case of disfluency corresponds to incomplete units. In this case, UD chooses to promote one element as the head of the unit and to attach the other elements to it [START_REF] Dobrovoljc | The Universal Dependencies treebank of spoken Slovenian[END_REF]. When this produces nonstandard relations, we propose adding a feature. In SUD, we add the feature scrap on these relations using @ as a separator (@scrap) This is converted into UD by inserting the Scrap=Yes feature on the dependent. Fig. 4 and 5 show some uses of @scrap. This feature is particularly useful for error mining: for instance, a relation between a verb and a determiner, as in Fig. 4, should not be allowed without a @scrap.

'it can have some …' Figure 4. Incomplete object (comp:obj@scrap).

'and they REFL, they both fall' Figure 5. Unknown relation inside a reparandum (unk@scrap).

Paratactic constructions

Paratactic constructions are particularly frequent in spoken corpora. The UD parataxis relation covers all cases where a finite verbal construction is neither the root of an utterance, nor a governed clause. In our corpora, we have identified seven different situations that we propose to distinguish: parataxis:obj, parataxis:discourse, parataxis:parenth, parataxis:insert, parataxis:dislocated, parataxis:mod, parataxis:conj.

The first occurs when an illocutionary unit occupies a governed position. The most common situation is reported speech in the object position of a verb of saying. In such cases, UD uses the relation parataxis, which we propose replacing with parataxis:obj. We add the feature Reported=Yes on the head of the reported IU, because some of them are not directly governed, such as the second reported IU in ( 19), ça pourrait être grave, encoded as a separate sentence.12 (19) après, elle a dit, on est aux affaires. ça être grave.

'then she said, we're in business. it could be serious.'

Thanks to the feature Reported=Yes, a standard comp:obj relation can be used in SUD and should be preferred because reported speech can commute with a complementizer phrase and, in accordance with SUD principles, two units that are in the same commutation paradigm must have the same syntactic function.

Another case of an IU in a governed position is called a graft by [START_REF] Deulofeu | Recherches sur les formes de la prédication dans les énoncés assertifs en français contemporain (le cas des énoncés introduits par le morphème que)[END_REF]. A graft is an IU that is produced in a position where a noun phrase is expected, such as the IU disons ma carrière pour simplifier 'let's say my career to simplify', which occupies a subject position.

(20) vous avez dit que, euh, disons ma carrière pour simplifier, témoigne de ma bonne conduite.

'you said that, uh, let's say my career to simplify, shows my good behavior.'

In such a case we use a plain subj relation rather than a parataxis relation, but we add a feature Graft=Yes. Some graft constructions are lexicalized such as the construction (21) from SUD_French-ParisStories, where an IU is introduced by the idiom en mode 'in the mode', or the construction ( 22), where a question is apposed to the word question 'question'.

(21) et là lui il l'a regardée en mode euh mais ça va madame ? 'and there he looked at her in the mode uh but is it ok miss ?' (22) alors on pourrait poser la question les écrivains ont-ils existé ?

'then one could ask the question did the writers exist?'

UD uses the relation discourse for discourse markers, except for verbal expressions, such as I mean, I guess, you know, etc., as in ( 23), as well as tag questions, where parataxis is used.13 This is a categorybased distinction that we believe is unwarranted. 14 In SUD, we decided to extend discourse for these cases, which is automatically converted into parataxis:discourse in UD. The relation has already been introduced in the UD spoken Slovenian treebank [START_REF] Dobrovoljc | The Universal Dependencies treebank of spoken Slovenian[END_REF]. ( 23) you know gote na kind of delicacy weh dem dey prepare // you know gote is a kind of delicacy which they prepare.'

The third case is parenthetical clauses or parentheses, which are real illocutionary units that could be autonomous, but which are inserted in the middle of another illocutionary unit, as my mama dey dat time 'my mum was alive at the time' in the Naija sentence (24) or je suis désolée 'I'm sorry' in the French sentence (25). We note them as parataxis:parenth.

(24) sometimes ( my mama dey dat time //) she go help me carry small // 'Sometimes, my mum was alive at the time, she would help me to carry a little.' (25) sauf que le clip, enfin, je suis désolée, mais il faisait pas très professionnel, hein.

(ParisStories_2020_concoursInstagram_49) 'except that the clip, well, I'm sorry, but it was not very professional, eh'

The fourth situation is that of incises or inserts, which are distinguished from parenthetical ones by the fact that they are not saturated and could not form an independent statement [START_REF] Bonami | On the syntax of direct quotation in French[END_REF]. They belong to a more formal register (news, sermons, stories, etc.). In French, they are also characterized by the inversion of the subject. We annotate them as parataxis:insert. An insert can be found at the end of an illocutionary unit. The fifth case is that of verbal constructions in the prenucleus position where they function as dislocations. In example (28), j'ai des copines actuellement 'I have friends at present' is clearly not an illocutionary unit (it is not asserted by the speaker that she has friends). It is a prenucleus, which can switch with a nominal phrase like mes copines 'my friends'. For the time being, we use dislocated for these cases in SUD and UD, but we consider revisiting it as parataxis:dislocated in UD. The sixth case of paratactic construction is the case of clausal modifiers that are not introduced by a subordinating conjunction. As in the previous case, the first clause creche no dey my office, lit. 'daycare is not (in) my office', is not asserted by the speaker and is a clear prenucleus. For such cases, we use parataxis:mod or simply mod in SUD (equivalent to UD advcl).

(29) creche no dey my office now < e for no dey easy // 'If I hadn't had a daycare in my office, it wouldn't have been easy.'

UD makes a seventh use of the parataxis relation, to link juxtaposed propositions, as in ( 19), taken from the spoken part of UD_English-GUM.

(30) God, I didn't spend the night, that's what makes me so mad, I'm grounded for nothing.

Our IU segmentation avoids this case most of the time; thus (30) can be perfectly split into three autonomous assertions. Nevertheless, in cases where we do not separate two juxtaposed or coordinated statements, we propose using parataxis:conj. In SUD_Naija-NSC, this relation has been used for sequences of parallel IUs. So far, we have not found any examples of parataxis which do not fit into one of the seven cases considered, and as we have shown, quite a few can be done away with in SUD (e.g. parataxis:obj, parataxis:discourse and parataxis:mod).

Conclusion

The goal of this paper was to present the additional features we have introduced in our spoken treebanks and to give some proposals for future developments of spoken treebanks, in order to converge on a common set of features. This concerns both practical recommendations for text-sound alignment (# sound_url, BeginAlign, EndAlign), and theoretical propositions concerning text segmentation into sentences, paradigmatic lists, and paratactic constructions.

Our set of relations and tags are meant to be extended to the annotation of constructions typical of spoken texts in other languages as well. This can only be verified by the elaboration of more spoken treebanks for typologically different languages. We hope that the phenomena presented in this paper will motivate other linguists to work on spoken language treebanks and that this paper can serve as a first guide in this endeavour.

#

  sound_url = http://www.tal.univ-paris3.fr/trameur/iTrameur-naija/mp3/KAD_22_Chatting-At-The-Restaurant_DG.mp3 #speaker_id = Sp205 #text = na wa for dat woman o !// #text_en = It's a shame for that woman! #text_ortho = Na wa for dat woman

Figure 2 .Figure 3 .

 23 Figure 2. Encoding of a co-construction (from SUD_French-Rhapsodie)

  11

(

  17) a. match nul, zéro partout pour Lille au Mans. (Rhap_M2006-72) 'draw, zero all for Lille at Le Mans.' b. et c'est dans cet esprit qu'est proposée par Szymanoski l'ouverture du concert, son opus douze. (Rhap_D2012-47)

'

  and he told me but you are wasting your time.' Figure 7. Reported speech.

  (26) vraiment, dit Job, la vie de l'homme sur terre est une corvée. (Rhap_M2003-33) 'truly, says Job, man's life on earth is a chore.' (27) alors, que va faire maintenant le président ? se demande Le Progrès à Lyon. (Rhap_D2013-45) 'So what will the president do now? wonders Le Progrès in Lyon.'

(Figure 8 .

 8 Figure 8. Parataxis:dislocated.

'

  then they went to the river, and they swam.' 15 Figure 9. Parataxis:conj.

observe me || dey observe my attitude

  16) a. from dat day < as I go meet am for shop < im con { dey

	} // (ABJ_GWA_12_Accident_MG__123)
	'From that day, as I went to meet him in the shop, he started observing me, observing my
	attitude.'
	b. mais le, le dis~, le commissaire du district, le préfet du lieu ne voulait pas de, de femme non
	mariée. (Rhap_D2004-11)
	'but the, the dis~, the district commissioner, the prefect of the place did not want any,
	unmarried woman.'
	c. euh, deux petites phrases, deux vraies options qui dessinent votre route, une route qui
	témoigne d'une certaine, d'une bonne, d'une très bonne conduite. (Rhap-D2001-3)
	'uh, two small sentences, two real options that draw your road, a road that testifies to a certain,
	a good, a very good conduct.'

SUD_Naija-NSC uses a macrosyntactic markup (see Section

3) with special punctuation signs, such as < or //. This markup is part of the annotated text, given in #text. An orthographic variant is proposed in #text_ortho, with traditional punctuation signs and an uppercase at the beginning of the sentence. Moreover an English translation is given in # text_en, as well as a gloss for each token.3 In the case of SUD_Naija-NSC, only some time boundaries were stored during the transcription process; others have been roughly assessed by dividing each time segment by the number of words. It would have been also possible to keep the features on some words only.

UD-Chukchi-HSE[START_REF] Tyers | Dependency annotation of noun incorporation in polysynthetic languages[END_REF] has a feature # text[phon], with a phonetic transcription, but it is not a feature specific to spoken corpora.

SUD_French-Rhapsodie is the former SUD_French-Spoken, which was initially the Rhapsodie treebank[START_REF] Kahane | Syntax and prosody mapping: What and how? The case of intonational periods and illocutionary units[END_REF]. The treebank has been renamed due to the introduction of a new treebank of spoken French, SUD_French-ParisStories. Rhapsodie uses a markup, where sentence boundaries are indicated by // and co-constructions by //+. Overlaps are indicated by $-…-$. But contrary to SUD_Naija-NSC, # text is based on standard punctuations and the macrosyntacic markup is stored in # macrosyntax.

UD requires the root of a tree to have the relation root.

Another solution could be to add quotation marks during the transcription, but this might become unreadable as the reported speech can span over a whole set of illocutionary units.

As shown by[START_REF] Kahane | Les parenthétiques comme « Unités Illocutoires Associées » : une perspective macrosyntaxique[END_REF], verbal discourse markers have properties that distinguish them from parentheses. They do not accept tense modifications and they cannot be modified. And they have a transitive verb without an overt object, but which takes its host as its object argument.

Many distinctions for relations are category-based in UD, such as nsubj vs csubj, for nominal vs clausal subjects, obj vs ccomp for nominal vs clausal objects, or amod vs advmod vs nmod, for adjectival vs adverbial vs nominal or adpositional modifiers.

Acknowledgements

We would like to thank our reviewers for their valuable remarks. Several people have participated in the development of our annotation schemes for spoken language. We are particularly grateful to Marine Courtin, Vanessa Gaudray-Bouju, Menel Mahamdi, and Mariam Nakhlé.


Liudmyla Klochko

Jörg Baschnagel

Joachim Wittmer

Alexander Semenov

Stress Fluctuations in Glass-Forming Systems: Elastic Response and Long-Range Correlations

Keywords: viscoelasticity, vitrification, polydispersity, colloids, correlations

The dynamics of two model glass-formers (3D oligomer melt and 2D polydisperse colloidal system) are analyzed using MD simulations. It is found that the standard deviation of the shear modulus shows a striking peak near the glass transition T g , which is explained with a quantitative theory. The simulation data well below T g suggest that static multi-point correlations of local stress are long-range. The obtained correlation functions of time-dependent and wavevector-resolved stress for the 2D system are in excellent agreement with the developed theory indicating that the frozen-in stress inhomogeneities in the glassy state are correlated according to a power law.

Introduction

Some liquids (in particular, polymer melts) can be easily supercooled avoiding crystallization (even if the crystal state is favorable thermodynamically). Such supercooled liquids show dramatic slowdown of their dynamics (reflected in a strong increase of the α-relaxation time τ α ) as temperature T is cooled towards the vitrification point T g where the system becomes kinetically arrested and forms an amorphous solid. Below T g the relaxation time τ α exceeds the time-scale t lab accessible experimentally (or in a computer simulation). The glass transition region around T g is characterized by a number of anomalies including a jump of the heat capacity, or an emergence of elasticity (of a finite quasi-static shear modulus µ) in a nearly discontinuous manner. However, this solidification is not accompanied by a significant change of the liquid structure which remains disordered. In particular, the static structure factor S(q) changes very little near T g . [1, 2] This common view implies that structural correlations in glass-forming systems must remain shortrange near and below T g . There is however a growing opinion that (at least for fragile glass-formers) the glassy structure is characterized by some (perhaps hidden and subtle) long-range correlations that are not visible in S(q). Indeed, this idea is supported by the mosaic or random first order transition (RFOT) theories [3, 4] , by the concept of frustration-limited domains [5, 6] and other approached. [3, 7, 8] In the present paper we show that investigations of stress fluctuations provide a powerful tool to study both the emergence of shear rigidity µ at the glass transition and the long-range structural correlations in supercooled liquids. [9, 10] We study two distinct glass-forming systems both theoretically and using MD simulations: The first system is a 3-dimensional (3D) melt of M oligomer chains, each of 4 beads. [10, 11] The beads interact pairwise with a Lennard-Jones potential u LJ (r) = 4 r -12 -r -6 (r is the distance between two particles) which was truncated at r cut = 2.3 and shifted so that u LJ (r) = 0 for r ≥ r cut . The bond potential is harmonic, u b (r) = 0.5k bond (r -l bond ) 2 with k bond = 1110 and l bond = 0.967 chosen to avoid chain crossings. The second system is a 2-dimensional (2D) polydisperse mixture of spherical LJ particles. Each pair of particles (of sizes d i and d j ) interact with energy u LJ (r/d ij ), where

d ij = (d i + d j ) /2.

Simulation details

The 3D system consists of M = 3072 or M = 768 4-mers. It was kept at pressure P = 0. It was equilibrated at different temperatures T by several relaxation stages as described in refs. [11, 12] . An ensemble of m = 100 independent configurations was produced. The stress tensor was recorded at regular time points t i :

t i = iδt, i = 0, 1, ..∆t/δt (1)
with the step δt = 0.05LJ over the whole sampling time of ∆t = 10 5 LJ (the time is measured using the LJ time unit [10] ). The 2D system [13, 14] involves N = 10 4 particles. The particle size d i , i = 1..N, is uniformly distributed between 0.8 and 1.2. The system was kept at constant external pressure P = 2 (in LJ units). It was equilibrated using the particle swap technique. [15] Periodic boundary conditions are always applied.

Results

Viscoelastic properties of a liquid can be characterized by the shear relaxation modulus G(t) which is a central rheological function of a material. G(t) is closely related to the dynamical moduli G ′ (ω),

G ′′ (ω), where t is time and ω, the angular frequency. To obtain G(t) for both systems we benefit from its relation to the temporal correlation functions of mechanical stress: where V is the system volume, σ(t) = σ xy (t) is the shear stress (xy component) averaged over the whole system, and the brackets ... mean averaging over the equilibrium ensemble which is equivalent to averaging over the time t ′ (below T g we consider a quasi-equilibrium ensemble corresponding to a particular glassy state, i.e., a metabasin in the configurational space).

C(t) = V T σ(t + t ′ )σ(t ′ )
The generalized relation coming from the fluctuation-dissipation theorem (FDT) [10, 12] reads:

G(t) = µ A + C(t) -C(0)
where µ A is the affine shear modulus providing the instantaneous stress response to a small affine deformation of the system (µ A was calculated as described before [10] ). Using the above relation, G(t) was obtained in the range 0 ≤ t ≤ 10 5 , and then the quasi-equilibrium shear modulus µ was calculated as a time-average of G(t): [10, 12]

µ = G(t i -t j ) = µ A -µ F
where ... here mean simple arithmetic average over i and j (cf. eq. 1), and µ F = (V /T ) (σ(t) -σ) 2 is the fluctuation modulus. [10, 12] The modulus µ defined above is close to G(t) for t ∼ ∆t both above and below T g . The obtained T -dependencies of µ = µ(T ) are shown in Fig. 1 (thick solid curves); the dotted vertical lines in Fig. 1 indicate T g in energy units. It is clear that µ is very small at high T , but starts to grow sharply right below T g . The standard deviation δµ of the modulus (across the ensemble of m independent configurations) is also shown in Fig. 1 (thin curves). The peak of δµ near T g obtained for both systems can be explained by the rigorous theory based on the assumption that the stress fluctuations are Gaussian. [10] The theoretical results are shown as dashed curves in Fig. 1. While the agreement is good around T g and above it, it is obvious that well below T g the simulated δµ is much higher than the theoretically predicted δµ (G) F . This discrepancy indicates that stress fluctuations must be strongly non-Gaussian at low T 's. Recalling that the Gaussian character of random variables averaged over a large system volume V naturally comes from their short-range correlations, the latter result also means that correlations of stress fluctuations must become longrange well below T g . This conclusion is also supported by the revealed system size dependence of the non-Gaussian part (δµ

(nG) F
) of δµ F : our data show that at low temperatures δµ (nG) F decreases with V slower than 1/V suggesting that the 4-point correlations of local shear stress decay with distance r slower than 1/r D , where D = 3 is the space dimension. [10] To study the stress correlation range for the 2D system more directly we analyzed the correlation function of the stress tensor σ αβ at different wave-vectors q (in addition to the space-averaged stress corresponding to q = 0). For each q we define the natural coordinate system with axis 1 along the wave-vector and axis 2 perpendicular to it. The generalized correlation functions are then defined as

C αβγδ (q, t) = V T σ αβ (q, t + t ′ )σ * γδ (q, t ′ )
where α, β, γ, δ = 1 or 2. The simulation results for C 2 (t) = C 2222 (q, t) are shown in Fig. 2 for q = 2π/L (L ≈ 100 is the system box size) at T = 0.3 and T = 0.24 (above and below T g ≈ 0.26).

The theoretical results obtained using the FDT relations derived before [9] are shown in Fig. 2 in Fig. 2. The ensemble of simulation data supports the theoretical prediction [9] that the only correlation function surviving coarse-graining at t t c is C 2222 . The smoothed version of this function, C 2∼ (t), just weakly depends on q for q ≪ q peak ∼ 5 (more precisely, it is independent of q with accuracy ∼ 5% for q 1). This leads to the following distance dependence of the time-smoothed correlation function of the local shear stress σ xy (r, t):

σ xy (r + r ′ , t + t ′ )σ xy (r ′ , t ′ ) ≃ T π C 2∼ (t) 1 r 2 - 8x 2 y 2 r 6
where r = (x, y). The above equation is valid for t ≫ t c and d ≪ r ≪ L. It means that the stress correlations decay as 1/r 2 in agreement with the previous simulation results [16] and theoretical predictions [9] .

Conclusions

For the 3D oligomer system we demonstrated that the quasi-equilibrium shear modulus µ shows an anomalously strong dispersion near the dilatometric glass transition temperature T g [10, 12] and that the system size dependence of this dispersion is indicative of the long-range 4-point static stress-correlations below T g (showing a slow power-law decay, possibly with an infinite correlation length). [10] The MD results for tensorial stress correlations in the 2D polydisperse system we studied show an excellent quantitative agreement with the theory that we developed before [9] both above and below T g . These new data also indicate that below T g the time-smoothed local stresses exhibit longrange spatial correlations decaying as 1/r 2 with distance r. In other words, the inherent structures of this system are characterized by pronounced correlations of the anisotropic stress [9] with almost infinite range, in agreement with the behavior reported for 2D and 3D Kob-Andersen (binary LJ) models. [16, 17]

FIG. 1 :

 1 FIG. 1: (a) Temperature dependence of the quasi-equilibrium shear modulus µ (thick solid line shows µ/4), its standard deviation δµ (thin solid line), and δµ (G) F , the theoretical Gaussian approximation of δµ F ≈ δµ (dashed curve) for the 3D 4-mer system with 12288 beads, with dilatometric T g = 0.38. (b) Similar dependencies of µ/8, δµ and δµ (G) F for the 2D polydisperse LJ system of N = 10 4 particles, T g = 0.26. In both cases the sampling time is ∆t = 10 5 LJ. The dotted vertical lines indicate T g .

  aswell. An excellent quantitative agreement (with no adjustable parameters) is evident. A similar agreement was also observed for other components of the correlation tensor C αβγδ , other T 's and other wave-vectors.It is instructive to coarse-grain the time-dependence of C αβγδ to remove the short-time oscillations with the period ∼ 2π/ (qc L ) ∼ 10 LJ, where c L is the longitudinal sound velocity. Such smoothed correlation functions C 2∼ (t) (with the coarsening time-scale t c ∼ 4π/ (qc L ) ∼ 20 LJ) are also shown

FIG. 2 :

 2 FIG.2:(a) Time-dependence of the stress correlation function C 2 (t) at wave-vector q = 2π/L for the 2D polydisperse LJ system at T = 0.3 (above T g ): direct simulation data (thin solid curve), theoretical predictions (thick dashed curve). Note that the two curves superimpose almost exactly. Thick solid curve corresponds to the smoothed correlation function C 2∼ (t) with no oscillations; t is time in LJ units, 0 < t < 10 5 . (b) Similar data for T = 0.24 (below T g ).