English. This paper presents the first release of LICO, a Lexicon for Italian COnnectives. LICO includes about 170 discourse connectives used in Italian, together with their orthographical variants, part of speech(es), semantic relation(s) (according to the Penn Discourse Treebank relation catalogue), and a number of usage examples.
Discourse connectives are explicit lexical markers that are used to express functional relations between parts of the discourse. As an example, the italian word “quando” in the sentence “Quando si preme sul bottone, la porta si apre da sola” (When you press the button, the door opens by itself) expresses a conditional relation between two parts of the sentence (from now on, arguments).
Work on discourse connectives in
Computational Linguistics was initially part of Rhetorical
Structure Theory
Our work on connectives is mainly motivated by the fact that, to the best of our knowledge, still there is no high coverage resource of discourse connectives available for Italian. LICO, the Lexicon for Italian COnnectives, aims at filling this gap, providing a repository of Italian connectives aligned with recent developments in discourse relations (i.e. the last version (3.0) of the Penn Discourse Treebank (PDTB)).
In addition, the LICO lexicon takes advantage
from DimLex, a similar repository for German
LICO is freely distributed under a CC-BY licence.
1http://www.cs.brandeis.edu/ clp/conll16st/
The definition of discourse connective is controversial both in traditional grammar and in the linguistic literature. Our definition is based on the encyclopedia entry on connectives by Ferrari (2010), included in the reference work for the Italian language recently published by Treccani. In this entry, connectives are defined as “each of the invariable forms [...], that introduce relations that structure “logically” the meanings of the sentence and of the text”2. The definition provided in Ferrari (2010) is restrictive, as it does not include variable forms, i.e. those forms which are subject to morphological modifications, such as ne consegue/conseguiva che ‘it follows/followed/ that’, nor does it include pragmatic uses of connectives (also known as discourse markers) such as causal perche´ ‘why’ in “Che ore sono? Perche´ ho dimenticato l’orologio” (‘what time is it? Because I forgot my watch’). On the other end, it assumes that logical relations marked by connectives hold between events or assertions, and therefore includes as arguments for the relation nominal expressions such as “dopo il pressante invito ...” ‘after the pressing invitation ...’, i.e. expressions that contain an event nominal, - although the event is, in this case, referred to instead of predicated.
In our work, we partly drop the invariability criteria; we do not include forms which exhibit morphological inflection or conjugation, but we do include connectives which show a certain degree of lexical variability that is, multi-word expressions which are not totally rigid from a lexical point of view (ad esempio/per esempio ‘for example’; see section 3). 3
Each entry in the LICO lexicon corresponds to a connective (including its variants). Currently, for each entry LICO specifies: whether the connective (or its variants) is composed by a single token (“part = single”, e.g. perche´) or by more than one token (“part = phrasal” e.g. di conseguenza); whether the connective is composed by correlating part (“orth = discont”) or not (“orth 2“Il termine connettivo indica in linguistica ciascuna delle forme invariabili [...], che indicano relazioni che strutturano ‘logicamente’ i significati della frase e del testo”. = cont”) and the specification of the two correlating parts, e.g. “orth = discont”: da una parte (“part = phrasal”), dall’altra (“part = phrasal”); “orth = cont”: perche´ (“part = single”); possible orthographic variants: e.g. cio` nonostante (“part = phrasal”) and ciononostante (“part = single”); possible lexical variants: e.g dopo di che´ and dopo di cio`. Notice that in some cases this lexical variants determine a different syntactic environment, such as in modo da and in modo che, the first being followed by infinitive form, the following by a subjunctive form; pos category: adverbs, preposition subordinating or coordinating conjunctions; the semantic relation(s) that the connective indicates, according to the PDTB 3.0 schema (see section 3.1); examples of the connectives for each semantic relation; possible alignments with lexicon of connectives in other languages.
Table 1 shows the entry for quando, which presents more than one semantic relation, and the entry for ciononostante, cio` nonostante, nonostante cio`, as example of a connective with orthografic variants in LICO. 3.1
For the annotation of the semantic relation we
used the PDTB 3.0 schema of relations
The schema is a most recent version of PDTB
2.0
rel. to German id: 116 entry-id orth part
variant orth part
variant orth part variant TEMPORAL: Asynchronous tag is used for connectives that indicate a before-after relation between the arguments. The third level (subtype level)3 varies according to the role of the two arguments involved in the relation. For example, CONTINGENCY:Cause:Reason is used if the argument introduced by the connective -Arg2- is the reason for the situation in the other argument -Arg1(e.g. I stayed at home, because it was raining), while CONTINGENCY:Cause:Results is used if Arg2 represents the result/effect of Arg1 (e.g. It was raining, therefore I stayed at home). Not every type has a further subtype.
In the LICO structure, each connective is assigned with one or more three-level tags. 4
In this Section, we present the current resource and its construction. In particular, we focus on describing how the list of entries has been identified so far and how we proceeded to acquire the semantic information for each entry.
List of connectives. Currently, LICO is composed by 173 entries, each one corresponding to 3The names of the levels are taken form Prasad et al. (2007). a connective and its orthographical or lexical variants. In order to compile this list we used a number of grammatical and lexical resources for Italian and for other languages.
First, we retrieved the list of connectives
mentioned by Ferrari (2010) in the Enciclopedia
Treccani for the entry connettivi4 for a total of 33
connectives. Then, we retrieved the list of connectives
tagged as congiunzione testuale in Sabatini Coletti
2006
In LICO connectives are tagged with the semantic relations that the connective can indicate in a text, selecting the most appropriate ones in the PDTB 3.0 schema. In this process we took advantage from the information which was already 4http://www.treccani.it/enciclopedia/connettivi (Enciclopediadell’Italiano)=, last access July 21st 2016.
5https://github.com/discourse-lab/dimlex dopo dopo di che dopodiche´ dopotutto dunque e ebbene eccetto eppure
dopo dunque e
DimLex
(equivalent)
dopo
dopodiche´ dopo di che
dopotutto
dunque
ebbene
eppure
dunque
e
eccetto
eppure
present in the resources we used for building the
list. In fact, the DimLex resource provides this
information for the German connectives, and both
the Italian resources previously mentioned
provide useful information about the semantic
relation triggered by the connective.6 A total of 23
different PTDB relations have been used to describe
LICO entries. In order to validate the tagging of
semantic relations, we conducted a research by
observing examples of the use of the connectives in
corpora, i.e. we wanted to verify whether the
relation that a connective introduces in a portion of
text is one of the relations already tagged for that
same connective in the first step. In particular, we
searched for 20 connectives in the ItWac corpus
To further confirm the corpus-driven evidences for the semantic relations, we asked two annotators (one being an expert annotator, the other not) to perform the same tagging task. We then calculated the interannotator agreement between the two annotators adopting the Dice’s coefficient (Ri6In particular, in the online version of Sabatini Coletti (http://dizionari.corriere.it/dizionarioitaliano/D/dizionario .shtml, last access July 21st 2016) the semantic relations the connectives can trigger are described in the definition of the connective itself, e.g. “quindi, cong. testuale: Con valore deduttivo-conclusivo, percio`, di conseguenza, per questo motivo, dunque”. Ferrari (2010) in the Enciclopedia Treccani proposes a non hierarchical classification which includes the following relations: “temporal relation” “causal relation”, “consequence relation”, “condition relation”, “opposition relations”. jsbergen, 1997)7 for three configurations, one for each level of the relation schema: class agreement, type agreement, subtype agreement. We considered that there was agreement if both annotators identify exactly the same class, type, subtype respectively. The Dice values result in 0,78 for class agreement and 0,71 for both type agreement and subtype agreement.
Observing cases of disagreement, we can make the following preliminary considerations. The main cases of disagreement regard the COMPARISON:Contrast relation (on one hand) and the COMPARISON:Concession and EXPANSION:Substitution relations (on the other hand). These relations in fact appear to be the ones that connect arguments that are in contrast. As an example, the connective anziche´ ‘rather than’ in Example (1) has been annotated as COMPARISON:Contrast by annotator1 and as EXPANSION:Substitution:Arg1-as-subst by annotator2: the first enlightens the contrast between “emissione attraverso il Tesoro” and “usare il tradizionale sistema”, the second emphasises that Arg2 represents the alternative to the Arg1. (1) [..] chiedeva l’ emissione di dollari in banconote statunitensi attraverso il Tesoro anziche´ usando il tradizionale sistema della Federal Reserve.
Another interesting case concerns the disagreement between the relations TEMPORAL:Asynchronous:precedence (in which Arg2 follows Arg1) and CONTINGENCY:Cause:Result (in which Arg2 is the results of Arg1), being the two strictly connected (i.e. in a cause-effect relation, the effect follows the cause). As an example, in (2) one annotator marks the connective as indicator of the temporal sequence of Arg1 and Arg2, while the other prefers to mark it as an indicator of the cause-effect relation. (2) [..] Il bello e` che i tipi hanno pure accennato a prendersela con me, al che io gli ho abbaiato contro una sequela di insulti [..] In general, the relations that were initially as7Dice’s coefficient measures how similar two sets are by dividing the number of shared elements of the two sets by the total number of elements they are composed by. This produces a value from 1, if both sets share all elements, to 0, if they have no element in common. signed to these connectives were confirmed by the corpus-based exercise (i.e. at least one annotator assigns the tag in at least one portions of text); viceversa, in some cases one of the two annotators assigned a relation that was not initially identified.8 5
In this paper we have presented LICO, a new resource for the Italian language describing lexical properties of discourse connectives. While LICO fills a gap with respect to similar resources existing for other languages, it is still under construction under several aspects. Our short term plans include the completion of the lexical entries with corpus derived examples and the observation of the connectives in Italian corpora, in order to acquire more information about the semantic relations that each connective can indicate and thus extend the annotation of the semantic relations in LICO.
We acknowledge Denise Pangrazzi for her contribution to identify the Italian equivalents of the German connectives.