eprintid: 10146158 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/14/61/58 datestamp: 2022-04-01 15:37:02 lastmod: 2022-04-01 15:37:02 status_changed: 2022-04-01 15:37:02 type: proceedings_section metadata_visibility: show sword_depositor: 699 creators_name: Dahlqvist, Fredrik creators_name: Schmid, Todd title: How to write a coequation ispublished: unpub divisions: C05 divisions: F48 divisions: B04 divisions: UCL note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: There is a large amount of literature on the topic of covarieties, coequations and coequational specifications, dating back to the early seventies. Nevertheless, coequations have not (yet) emerged as an everyday practical specification formalism for computer scientists. In this review paper, we argue that this is partly due to the multitude of syntaxes for writing down coequations, which seems to have led to some confusion about what coequations are and what they are for. By surveying the literature, we identify four types of syntaxes: coequations-as-corelations, coequations-as-predicates, coequations-as-equations, and coequations-as-modal-formulas. We present each of these in a tutorial fashion, relate them to each other, and discuss their respective uses. date: 2021-09-03 date_type: published publisher: Coalgebra official_url: https://www.coalg.org/calco-mfps2021/ oa_status: green full_text_type: other language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 1889785 lyricists_name: Dahlqvist, Fredrik lyricists_id: FPHDA09 actors_name: Dahlqvist, Fredrik actors_id: FPHDA09 actors_role: owner full_text_status: public pres_type: paper series: Conference on Algebra and Coalgebra in Computer Science (CALCO 2021) volume: 9 place_of_pub: Salzburg, Austria event_title: 9th Conference on Algebra and Coalgebra in Computer Science (CALCO 2021) book_title: Proceedings of the 9th Conference on Algebra and Coalgebra in Computer Science (CALCO 2021) citation: Dahlqvist, Fredrik; Schmid, Todd; (2021) How to write a coequation. In: Proceedings of the 9th Conference on Algebra and Coalgebra in Computer Science (CALCO 2021). Coalgebra: Salzburg, Austria. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10146158/1/2109.11967v1.pdf