tetrahedrons, the parameters of which can be computed directly. He implemented the updated model on a Sinclair ZX Spectrum personal home computer. In 1982 a team, led by Jakopin, made the survey of a 450 m long section of Postojnska jama cave, from the Concert Hall to the end of the Great Mountain, and the model yielded a volume of 313,000 m3 In 1984 Daniel Rojšek and his team measured a 54 m long segment of the Martel's Hall at the end of Škocjanske jame caves with a volume of 220,000 m3, one tenth of the entire hall volume (2,200,000 m3), computed in 2018. It is comparable in size to other large underground chambers. In 2019 and in 2020 Jakopin wrote articles about three people who devoted most of their life to deep caves, to achieve depths greater than 2,000 meters: Pavel Demidov in Verëvkina Cave, Jurij Kasjan in Voronja Cave and Aleksandr Višnjevskij in Boybuloq. Family His father Franc Jakopin was a Slovenian slavist, lexicographer and onomatologist, his mother Gitica Jakopin was a translator, writer and a poet, his brother Japec Jakopin is a yacht concept designer and his brother Jernej Jakopin is a naval architect. Publications CORTES - a text corpus of Slovenian. In publication: Digital resources for the humanities: Conference abstracts (University of Sheffield, 10–13 September 2000). - Sheffield: University of Sheffield, 2000. - p. 70-72. EVA - an Internet tool for textual and lexical resources. In publication: Linguistics and language studies / 32nd Annual Meeting, Ljubljana, 8–11 July 1999. - Ljubljana: University, Faculty of Arts: Societas Linguistica Europaea, 1999. - p. 98. The feasibility of a complete text corpus. LREC 2002: proceedings. On text corpora, word lengths, and word frequencies in Slovenian. In publication: Contributions to the science of text and language / edited by Peter Grzybek. - Dordrecht: Springer, 2006. (Text, speech and language technology; vol. 31). - . - p. 171-185. Query-driven dictionary enhancement. Co-author: Birte Lönneker. In publication: Proceedings of the Eleventh EURALEX International Congress, EURALEX 2004, Lorient, France, July 6–10, 2004 / Geoffrey Williams and Sandra Vessier (eds.). - Lorient: Université de Bretagne-Sud, cop. 2004-. - p. 273-284. Slovenian texts on the internet. In publication: Zapiski: Chronicle of the American Slovene Congress. Issue 7 (May 2000), p. 4-7. Words and nonwords as basic units of a newspaper text corpus. In publication: COMPLEX 2001 / 6th Conference on Computational Lexicography and Corpus Research