Annotated, they have been used in
corpus linguistics for statistical
hypothesis testing, checking occurrences or validating linguistic rules within a specific language territory.
In
search technology, a corpus is the collection of documents which is being searched.
Overview
A corpus may contain texts in a single language (monolingual corpus) or text data in multiple languages (multilingual corpus).
In order to make the corpora more useful for doing linguistic research, they are often subjected to a process known as
annotation. An example of annotating a corpus is
part-of-speech tagging, or POS-tagging, in which information about each word's part of speech (verb, noun, adjective, etc.) is added to the corpus in the form of tags. Another example is indicating the
lemma (base) form of each word. When the language of the corpus is not a working language of the researchers who use it,
interlinear glossing is used to make the annotation bilingual.
Some corpora have further structured levels of analysis applied. In particular, smaller corpora may be fully
parsed. Such corpora are usually called
Treebanks or
Parsed Corpora. The difficulty of ensuring that the entire corpus is completely and consistently annotated means that these corpora are usually smaller, containing around one to three million words. Other levels of linguistic structured analysis are possible, including annotations for
morphology,
semantics and
pragmatics.
Applications
Corpora are the main knowledge base in
corpus linguistics. Other notable areas of application include:
The analysis and processing of various types of corpora are also the subject of much work in
computational linguistics,
speech recognition and
machine translation, where they are often used to create
hidden Markov models for part of speech tagging and other purposes. Corpora and
frequency lists derived from them are useful for
language teaching. Corpora can be considered as a type of
foreign language writing aid as the contextualised grammatical knowledge acquired by non-native language users through exposure to authentic texts in corpora allows learners to grasp the manner of sentence formation in the target language, enabling effective writing.[1]
Multilingual corpora that have been specially formatted for side-by-side comparison are called aligned parallel corpora. There are two main types of
parallel corpora which contain texts in two languages. In a translation corpus, the texts in one language are translations of texts in the other language. In a comparable corpus, the texts are of the same kind and cover the same content, but they are not translations of each other.[2] To exploit a parallel text, some kind of text alignment identifying equivalent text segments (phrases or sentences) is a prerequisite for analysis.
Machine translation algorithms for translating between two languages are often trained using parallel fragments comprising a first-language corpus and a second-language corpus, which is an element-for-element translation of the first-language corpus.[3]
Text corpora are also used in the study of
historical documents, for example in attempts to
decipher ancient scripts, or in
Biblical scholarship. Some archaeological corpora can be of such short duration that they provide a snapshot in time. One of the shortest corpora in time may be the 15–30 year
Amarna letters texts (
1350 BC). The corpus of an ancient city, (for example the "
Kültepe Texts" of Turkey), may go through a series of corpora, determined by their find site dates.
^Wolk, Krzysztof; Marasek, Krzysztof (2015). "Tuned and GPU-accelerated parallel data mining from comparable corpora". In Král, Pavel; Matousek, Václav (eds.). Text, Speech, and Dialogue – 18th International Conference, TSD 2015, Pilsen, Czech Republic, September 14–17, 2015, Proceedings. Lecture Notes in Computer Science. Vol. 9302. Springer. pp. 32–40.
arXiv:1509.08639.
doi:
10.1007/978-3-319-24033-6_4.