Designing an Extensible Domain-Specific Web Corpus for “Layfication”: A Case Study in eCare at Home

Introduction

Cyber-Physical Systems (CPSs) denote an emergent paradigm that combines most advanced technological approaches and computational tools to solve complex tasks. CPSs are domain-independent and have penetrated diversified disciplines, such as healthcare and self-driving vehicles. Corpus-based Language Technology is an essential component of many CPSs, where linguistic knowledge is indispensable to prevent failures or fatal errors due to misunderstandings or poor understanding.

Web corpora are the bedrock underlying modern real-world corpus-based Language Technology applications (henceforth LT applications), such as terminology extraction, ontology learning, text simplification, automatic summarization and machine translation. In this chapter, we describe the design and the development of an extensible domain-specific web corpus to be used in a distributed social application for the care of the elderly at home.

Web corpora are text collections made of documents that have been automatically retrieved and downloaded from the web. Generally speaking, building web corpora is convenient because the whole process of corpus creation is automated, fast and inexpensive. In contrast, the construction of traditional corpora ̶ such as the British National Corpus (BNC) (Burnard, 2007) or the Corpus of Contemporary American English (COCOA) (Davies, 2009) or the recent iWeb corpus¹ ̶ normally spans over several years, relies on considerable amount of human expertise to decide the ideal combination of documents that is worth storing in the corpus and, last but not least, necessitates substantial funding. It goes without saying that the investments in time, financial resources and human knowledge required by traditional corpora are well paid-off because such an effort amounts to high-quality and long-lasting collections, that are extensively used by teachers, students, researchers and system developers. For instance, the Brown corpus created in the 60's (Kucera & Francis, 1979) is still valuable today, especially for monitoring how the language has changed in the last decades (e.g. Malá, 2017).

While traditional corpora are a shrine of hand-crafted qualities, the added value of web corpora is in their malleability. Similar to traditional corpora, web corpora can be general-purpose or specialized (Barbaresi, 2015) and may serve different purposes, such as linguistic studies (e.g. Schäfer & Bildhauer, 2013; Biemann et al., 2007; Lüdeling et al. 2007) and professional uses (Goldhahn et al., 2012; Baroni et al., 2006). However, the unique and unprecedented potential of web corpora is that they can promptly and inexpensively account for virtually any domain, topic, genre, register, sublanguage, style and emotional connotation, since the web itself is a panoply of linguistic and textual varieties. This potential can be profitably exploited for domain-specific projects that require specialized text collections to implement corpus-based LT applications. Examples of these types of LT applications are those implemented in projects like DigInclude² and E-care@home³ in Sweden or those that have been developed for European projects, such as SEMANTICMINING⁴ and SemanticHealthNet⁵ in the semantic interoperability field, as well as Accurat⁶, TTC⁷ and EXPERT⁸ in Natural Language Processing (NLP), Computational Linguistics and Information Retrieval.

Arguably, traditional corpora and web corpora are complementary and allow for a wide spectrum of possible linguistic, empirical and computational studies and experiments.