Building ASLN et, a W ordnet for A merican S ign L anguage (2019)

Abstract: We discuss the creation of ASLNet by aligning the Princeton WordNet (PWN) with SignStudy, an online database of American Sign Language (ASL) signs. This alignment will have many immediate benefits for first and second-sign language learners as well as ASL researchers by highlighting semantic relations among signs. We begin to address the interesting theoretical question of to what extent the wordnet-style organization of the English lexicon (and those of wordnets in other spoken languages) is applicable to ASL, and whether ASL requires positing additional, language or modality-specific relations among signs. Significantly, the mapping of SignStudy and PWN provides a bridge between ASL and the worldwide wordnet community, which comprises speakers of dozens of languages working in academic and language technology settings.

## background and motivation we discuss plans for developing aslnet, the large-scale alignment of the princeton word-net @xcite and sign-study ( www.signstudy.org ), a database of american sign language (asl) signs. the popularity of the princeton wordnet (pwn) has spawned wordnets in dozens of other spoken languages @xcite , including those outside the indo-european language family. crossing modalities, imagenet @xcite , a database created to support image recognition, contains thousands of images linked to pwn's synsets. sign languages fall squarely within the family of human languages but communicate meaning in the visual-kinesthetic modality. aligning the synsets of pwn (and by extension those of the wordnets in other spoken languages) with asl signs is both a logical and challenging next step. ## enhancing ss with pwn relations a promising method for the semantic organization of ss's signs is to map them to pwn, creating aslnet. however, it is critical to avoid the misconception that asl is simply a signed version of english, which leads to the incorrect impression that one may develop aslnet by the simple mapping of signs to their corresponding english words in pwn. as is the case with creating wordnets for languages other than english, aslnet-internal additions are required to accommodate links among signs, some of which are not (and cannot) be encoded for wordnets representing the lexicon of a spoken language. with this in mind, we emphasize that our objective is to utilize the semantic structure offered by pwn to assist with the semantic organization of asl signs and their linking to corresponding senses in other languages with wordnets. there are multiple benefits resulting from a mapping of asl signs to pwn entries. deaf and hearing learners of asl can explore the asl lexicon by following the links in multiple, intuitive ways. for example, if the signs hand and finger are linked to pwn synsets containing (the corresponding senses of) hand and finger, the semantic relation between these two words (meronymy, the part-whole relation) that is encoded in pwn will be transferred to the signs. ss does not need to independently encode such relations among signs, so long as signs and pwn words are semantically equivalent. a structured lexical resource for asl will offer major pedagogical benefits and enable semantically-driven learning of asl @xcite ). it will support language acquisition by deaf children by enabling them to quickly acquire the meanings of new signs. for example, the signs legislature and judi-ciary could be linked to the sign govern-ment by the meronymy relation; the signs ex-pensive and cheap by the antonym relation, etc. children's books designed to foster word learning commonly present words in such semantically related groups. second-language students of asl will be able to expand their asl lexicon by diving into a semantic rabbit hole as they discover a sign that leads them to semantically related signs, and so on. entire lessons could be organized semantically so that critical areas of the lexicon are quickly filled out with meaningfully related signs. perhaps the most important benefit of linking asl to pwn is the immediate connection to dozens of wordnets in other languages. pwn can be thought of as the hub to which wordnets in many languages are linked. departing from a given signed word will allow one to go from the corresponding english word to its equivalents in spanish, basque and hindi, for example. additionally, the link between pwn and imagenet raises interesting possibilities for exploring questions of iconicity in asl @xcite . ## related work we are aware of only one effort to link wordnets to a database of signs. @xcite describe plans for developing a sign bank for italian sign language (lis) and its alignment to multiwordnet @xcite , a lexical database for italian, romanian, spanish, portuguese, latin and hebrew modeled on, and linked to an early, smaller version (1.6) of pwn that is no longer the standard for natural language processing applications. however, while the concept of lis was developed and described in @xcite , to the best of our knowledge, the lis sign bank was not in fact created. ## units of meaning both ss and pwn are databases whose atomic units are form-meaning mappings. however, there are inherent technical challenges to aligning such pairings across different modalities. spoken and written words are discrete units of form-meaning mappings. by contrast, signed words are expressed through movement in continuous space. this allows signers to modify a given meaning in a continuous manner in many cases; signers are not necessarily limited to the words of a spoken language that divides a range or scale into discrete steps. additionally, while there also exist signs with quasi-discrete differences in meaning, boundaries between these meanings may not always be clear-cut due to the continuous nature of signing. consequently, a successful mapping between discrete spoken words and continuous signed words requires a careful analysis of the meaning(s) of asl signs. ## aslnet-specific links as asl possesses linguistic properties distinct from those of spoken languages such as english, aslnet-internal additions are required to accommodate links among signs. without those modifications, aslnet runs the risk of projecting asl into an incompatible framework, preventing its study without biases towards spoken languages. ## implementation we discuss methods and steps required for building aslnet. ## future work once aslnet v1.0 is completed, the resulting wordnet will be analyzed for any novel characteristics and properties. these results will be reported along with an analysis of our proposed development procedure and its effectiveness. along with remedying any difficulties encountered during v1.0 development, building v1.1 will include identifying the mapped nouns that belong to noun-verb pairs along with the consideration of modified lexical nouns (e.g., with the use of classifier constructions). such mappings are likely to be challenging for reasons discussed in section 4. v1.1 will be followed by subsequent versions that incorporate mappings for increasingly complicated aspects of asl, particularly those that differ significantly from spoken languages. once mapping techniques have been developed and proved viable for the core aspects of asl, large-scale lexical expansion of aslnet may then commence. such work may lead to aslnet becoming a part of the collaborative interlingual index (cili), a means of linking wordnets without depending on pwn's semantic structure @xcite . cili integration may be beneficial in the face of lexical gaps as well as differences in word encoding and linking between asl and english. it is also important to be mindful of the fact that sign languages are not universal; there exist many other sign languages distinct from asl. as the lin-guistic properties of other sign languages may not be entirely identical to those of asl, it is rewarding to develop the structure of aslnet such that it is as general as possible with regard to sign languages so that this work may give rise to similar research opportunities with other sign languages without unintentionally introducing a bias towards asl. this is comparable to how pwn led to the development of wordnets for additional languages. ## conclusion this work opens many interesting avenues for research. as discussed previously, developing aslnet will provide insight into lexical gaps between asl and english. with the inclusion of asl verbs, aslnet will permit the exploration of verb troponymy within asl. by highlighting semantic relationships between signs, aslnet may also offer insights into many properties of asl, including systematic metaphoricity, compounds, idiomatic expressions, compositionality and similarities, and iconicity. furthermore, since aslnet will be linked to pwn, and in extension, wordnets for many other languages, comparisons of these linguistic properties may be made between asl and other languages.