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The UD_Czech-CAC treebank is based on the Czech Academic Corpus 2.0 (CAC; Český akademický korpus; ČAK), created at Charles University in Prague.


CAC consists both of written data and transcripts of spoken language. Only the written part is included in this treebank as no syntactic annotation is available for the spoken data. Out of 650,000 total CAC tokens, 493,306 appear in the treebank.

The first version of CAC was created by a team from the Institute of the Czech Language, Czechoslovak Academy of Sciences, led by Marie Těšitelová, in 1971-1985; its original name was “Korpus věcného stylu”. It was reshaped and made compatible with the Prague Dependency Treebank between 2007 (CAC 1.0) and 2008 (CAC 2.0); these corpora are distributed by the Linguistic Data Consortium. The corpus has now been converted to Universal Dependencies and made freely available under the CreativeCommons license (see LICENSE.txt).

See the following websites for more information on CAC 2.0:

CAC contains mostly unabridged articles taken from a wide range of media. These articles include newspapers, magazines and other sources covering administration, journalism and scientific fields. These three genres can be distinguished by the sentence id: in

# sent_id = a-s20w-s55

the "s20w" part identifies the source document, where "w" means "written", "20" is the document id number and "s" means scientific (while "a20w" is the twentieth document from the administrative genre, and "n20w" from newspapers).

The texts are taken from the 1970s and 1980s and thus, the selection of texts is influenced by the political and cultural climate of this time period.

The original data in “Korpus věcného stylu” omits all punctuation symbols, numbers (only those expressed in digits; numeral words are preserved) and some measure units and symbols. The missing tokens were manually restored in CAC; however, for numbers and units, only a wildcard was inserted as the exact value and form cannot be guessed without access to the primary document.


We wish to thank all of the contributors to the original annotation effort, as well as the team responsible for the corpus' revival in 2008.


  • Barbora Vidová Hladká, Jan Hajič, Jiří Hana, Jaroslava Hlaváčová, Jiří Mírovský, Jan Votrubec: Průvodce Českým akademickým korpusem 1.0/ The Czech Academic Corpus 1.0 Guide. Karolinum, Praha, 2007. ISBN 978-80-246-1315-4.
  • Barbora Vidová Hladká, Jan Hajič, Jiří Hana, Jaroslava Hlaváčová, Jiří Mírovský, Jan Raab: The Czech Academic Corpus 2.0 Guide. In: The Prague Bulletin of Mathematical Linguistics, No. 89, Copyright © Univerzita Karlova, ISSN 0032-6585, pp. 41-96, Jun 2008.
  • Marie Těšitelová: K jazyku věcného stylu z hlediska kvantitativního (On the language of non-fiction style from the quantitative point of view). In: Slovo a slovesnost, vol. 44, no. 4, pp. 275-283, Praha, 1983.


  • 2023-05-15 v2.12
    • Temporary fix of double subjects (second subject converted to dep). In the long run, the cause should be found and fixed upstream.
    • Added the enhanced relation subtype nsubj:xsubj.
  • 2022-05-15 v2.10
    • Added VerbForm=Part|Voice=Pass to long forms of passive participles.
    • Added VerbForm=Vnoun to verbal nouns.
    • The verb 'být' is now AUX in all contexts.
    • Merged PRON/DET 'sám', 'samý'.
  • 2021-05-15 v2.8
    • "§" is now SYM instead of NOUN.
    • Fixed recognition of clauses with passive participles (ADJ).
  • 2020-11-15 v2.7
    • Restored some prepositions and other missing words.
    • Adjusted treatment of double lemmas like "m`metr".
  • 2020-05-15 v2.6
    • Genitive, dative and instrumental nominals are now considered oblique.
    • Added enhanced relations with case information.
    • Added enhanced relations around relative clauses.
    • Added enhanced external subjects in control verb constructions.
    • Added empty nodes to enhanced graphs (but orphans are just converted to dep).
  • 2019-05-15 v2.4
    • Modified conversion: nouns do not have objects.
    • Fixed punctuation attachment.
    • Fixed some annotation errors.
  • 2018-11-15 v2.3
    • Split multi-word tokens "cos, ses, sis, tys, vždyťs", participle + "-s".
    • Bug fix: conditional "by" should be attached as 'aux', not 'aux:pass'.
    • Flat name structures extended to titles and occupations.
    • Added LDeriv for passive participles (the infinitive of the source verb).
  • 2018-03-01 v2.2
    • Added enhanced representation of dependencies propagated across coordination. The distinction of shared and private dependents is derived deterministically from the original Prague annotation.
    • Fixed computation of the LDeriv MISC attribute.
  • 2017-11-15 v2.1
    • Retagged pronouns “každý” and “kterýžto”.
    • Prepositional objects are now “obl:arg” instead of “obj”.
    • Instrumental phrases for demoted agents in passives are now “obl:agent”. 2017-03-01 v2.0
  • 2017-03-01 v2.0
    • Converted to UD v2 guidelines.
    • Reconsidered PRON vs. DET. Extended PronType and Poss.
    • Improved advmod vs. obl distinction.
    • L-participles are verbs, other participles are adjectives.
  • 2016-05-01 v1.3
    • Initial release.

=== Machine-readable metadata (DO NOT REMOVE!) ================================ Data available since: UD v1.3 License: CC BY-SA 4.0 Includes text: yes Genre: news nonfiction legal reviews medical Lemmas: converted from manual UPOS: converted from manual XPOS: manual native Features: converted from manual Relations: converted from manual Contributors: Hladká, Barbora; Zeman, Daniel Contributing: elsewhere Contact:

Original CAC authors: Hladká, Barbora; Hajič, Jan; Hana, Jiří; Hlaváčová, Jaroslava; Mírovský, Jiří; Raab, Jan Original KVS authors: Těšitelová, Marie