SYN2015 is a representative corpus of contemporary written Czech published in December 2015. SYN2015 is a sequel of the representative corpora of the SYN series (SYN2000, SYN2005, SYN2010), but at the same time, it reflects necessary methodological and technological enhancements outlined below.

SYN2015 is designed as a representation of contemporary printed language of the last five-year period, i.e. 2010–2014. As the borders of synchronicity vary across the registers, the following criteria for inclusion of the individual texts into SYN2015 have been adopted (based on the three top-level categories, cf. below):

• fiction: publication date within the last 25 years and first publication date within the last 75 years;
• non-fiction: first publication date within the last 25 years;
• newspapers and magazines: publication date within the given five-year period.

The approach adopted to representativeness differs from previous corpora of the SYN-series. SYN2015 contains a large spectrum of different types of texts in order to cover vast majority of varieties the corpus aims to represent. This corresponds to Biber's notion of representativeness in terms of texts as products. Unlike the previous corpora in this series, SYN2015 is designed as representative, but not claimed to be balanced.

The original text classification scheme of the SYN series has been updated and revised; both original and revised classifications are based on text-external criteria that reflect predominant function of a text. The revision has been made with respect to comparability with the original scheme, with the most significant change made to the sub-classification of non-fiction adopted from the Czech National Library and more detailed classification of newspaper texts.

Composition of non-fiction (NFC) part of the SYN2015

Proportion of traditional and leisure journalism within the newspapers and magazines in each year

In line with its predecessors, SYN2015 contains a large variety of texts from various publishers within the given classification category. A category is defined by a combination of two variables: text type and genre. Proportions of the particular categories in SYN2015 are set arbitrarily, yet close to the original figures.

Next to the text type and genre, metadata related to the text classification and available for every document also include medium (book, journal, textbook etc.), periodicity (daily, weekly, monthly, less than monthly, non-periodical) and audience (general, children/youth). Standard division of the newspapers into the individual articles is also supplemented by their separate classification into 13 sections (politics, economics, sports, culture, leisure, commentaries etc.) and information about the author that is available for all prominent newspaper titles.

A more detailed description of the text types contained within the macro groups:

A detailed information about the text classification scheme is available on a special web page.

We are working under the assumption that a synchronic text is one that is still being read (or published), which is indicated by the year of publication. The boundaries of synchrony differ for each of the three macro groups:

• for fiction it is 25 + 75, i.e. the time elapsed since the first publication is less than 75 years (approximately three living generations) and the given issue of the text being added to the corpus is no older than 25 years (ensuring reception in the present),
• for non-fiction texts the first issue must be no older than 25 years,
• the boundaries for the synchrony of newspapers and magazines remains unchanged, i.e. the text must have been published in the period which is being mapped by the corpus (in the case of SYN2015 it is the period between 2010 and 2014).

The resulting makeup of the corpus in no. of words over the years is summarized by the following graph.

Proportion of fiction, non-fiction, newspapers and magazines in each year

Compared to previous versions there have been improvements in lemmatization and morphological tagging; both are almost identical to the processes used for the corpus SYN2013PUB, nonetheless SYN2015 was processed using the newest versions of all the tools (the improvements relate both to the morphological dictionary and to the rule-based disambiguation). Furthermore, the lemmatization of punctuation marks has changed, preserving the form of the characters as much as possible.