Are there just W ord N ets or also S ign N ets? (2023)

Abstract: For Sign Languages (SLs), can we create a SignNet, like a WordNet for spoken languages: a network of semantic relations between constitutive elements of SLs? We first discuss approaches that link SL data to wordnets, or integrate such elements with some adaptations into the structure of WordNet. Then, we present requirements for a SignNet, which is built on SL data and then linked to WordNet.

## introduction wordnets are semantic networks for in se spoken natural languages, containing lexical semantics relations between the words (mainly for nouns, verbs, adjectives and adverbs) in these languages. full wordnets are currently only available for spoken languages, encoded in written form. in many cases, there are links between distinct wordnets, often using princeton wordnet @xcite as a pivot, using interlingual wordnet indices @xcite . there is an increasing interest in offering automated translations between spoken and signed natural languages. this is demonstrated by two ongoing large european research projects: signon 1 @xcite and easier 2 (mcdonald et al., 2021). the topic of automated translations between sign languages (sls) is also being addressed. research is also addressing the role that word-net(s) can play. @xcite , for instance, shows how to include sl data in wordnet(s) and 1 https://signon-project.eu/ 2 https://www.project-easier.eu/ how the shared synset ids in the open multilingual wordnet (omw, @xcite ) infrastructure can help in cross-linking and aligning signs used in both german and greek sign languages. this extends related work on building aslnet @xcite , which deals with princeton wordnet (pwn) and american sign language (asl), using the semantic structure offered by pwn to support the semantic organization of asl signs. complementary to this, we investigate whether the development of a specific (lexical) semantic network for sl data is an option for establishing (crosslingual) semantic relations between elements of sl data sets and whether it supports a better linking to wordnets related to spoken languages, instead of "merely" integrating sl data in wordnet(s). we call such networks signnets. constructing sign languages specific signnet(s) may help to bridge between sign languages and spoken languages. @xcite already express the need to encode sl specific phonological and lexical relations (going beyond purely pwn-based relations) between asl signs. it may be worth considering extending this approach to a full signnet. a signnet can help in the extended publication and visibility of (some) sl data, as we can consider all sls as low resource languages, esp. when taking into account that the resources should be machine-readable to overcome some translation issues, esp. when using mt. so, for example, a significant part of the corpus for the flemish sign language (vlaamse gebarentaal, vgt) is not yet machine-readable, cf @xcite . in the vgt dictionary foot_0 each sign comes with a few keywords, but esp. when translating from spoken (northern) dutch to vgt, several words are missing. the availability of hypernyms etc may also be useful. making use of signnets and wordnets, esp when translating from spoken language to sign language, it becomes easier to detect which words can be related to which signs. this is one of the possible uses in a project like signon, dealing with low resource languages. a last, but important issue: a wordnet should ideally be accessible to users having the language under consideration as their mother tongue, cf the app for pwn 3.1. 4 for a language like vgt it should be accessible in that sl (their mother tongue), not just in a 'foreign' spoken language. thus, work on resources for greek and german, spoken and signed, are well under way, while currently work on aslnet seems to be more or less at a standstill. however, it seems that in none of these cases a full 'wordnet' for an sl (a signnet?) is being built. as mentioned above, in se, a wordnet is a large semantic network stored in a database. we aim at including in such a semantic network all types of data available for a specific sl, also signs (and images/videos showing them), with their phonological elements, like hand shapes, position, orientation, as well as the glosses, foot_2 their phonetic transcriptions (like hamnosys @xcite , cf. fig. 3 ), examples of use (in both the sl environment and the surrounding spoken language), definitions and identifiers of entries in corpora, where some attestations of the signs can be found, etc. this would make signnets semantic networks on their own, applied to visual-gestural data, and containing links to wordnets, rather than being integrated in those. we are framing sls as natural languages in their own right, and not as an appendix to spoken language (spoken language with signs/gestures). the latter was more or less the case, although with pictographs, in @xcite where pictographs were linked to cornetto foot_3 synsets in order to enable people with intellectual disabilities to communicate with others using an app. ## an application under construction the glossing system described above is widely used by linguists. but there is this major difference between using words and glosses, the latter in fact representing a series of words (synset) from the beginning. and quite often representing a broader concept for gloss x than the one reflected in the synset resulting from the search for word x, sometimes also smaller! a semantic network for sls (signnet) also presenting such data is to be set up more or less from scratch, taking advantage of the wordnet of a surrounding spoken language. for both vgt and ngt that would be odwn. 15 however, this might involve adaptations in the (spoken) wordnet, in our case odwn, as well. in selecting the odwn synsets to connect with a vgt gloss, the few words in spoken language (keywords) provided by the people behind the vgt dictionary 16 are really helpful. we will also provide links with other wordnets and signnets. the central position of princeton wordnet will be replaced by open english word-net @xcite , derived from pwn, and updated regularly. we will also make use of open multilingual wordnet to connect with other wordnets @xcite . ## conclusion our pilot study made it clear to us that building real signnets, comparable with wordnets for spoken languages, is possible, doing justice to the characteristics of the sign language under consideration. mainly linking signs with surrounding wordnet synsets does so to a lesser extent. another advantage is that, for example, an application comparable to that of princeton wordnet 3.1, but for sls, is accessible to a much larger set of users. so, we'll continue working on developing signnets! our signnets are in some respect an extension of the work done by @xcite , @xcite , and @xcite . their results can in se be used as a first step towards a full signnet, and be extended with for example examples in the relevant sls, recognition of video of a particular sign, etcetera.