TY  - UNPB
N1  - This version is the author accepted manuscript. For information on re-use, please refer to the publisher?s terms and conditions.
AV  - public
Y1  - 2021/09/03/
TI  - How to write a coequation
A1  - Dahlqvist, Fredrik
A1  - Schmid, Todd
T3  - Conference on Algebra and Coalgebra in Computer Science (CALCO 2021)
CY  - Salzburg, Austria
PB  - Coalgebra
UR  - https://www.coalg.org/calco-mfps2021/
ID  - discovery10146158
N2  - 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.
ER  -