@incollection{Bekić1984,
 title = {Definable operations in general algebras, and the theory of automata and flowcharts},
 author = {Bekić, Hans},
 year = {1984},
 isbn = {978-3-540-38933-0},
 doi = {10.1007/BFb0048939},
 url = {https://doi.org/10.1007/BFb0048939},
 booktitle = {Programming languages and their definition: {H}. {Bekič} (1936–1982)},
 editor = {Jones, C. B.},
 pages = {30--55},
 publisher = {Springer Berlin Heidelberg},
 address = {Berlin, Heidelberg},
 abstract = {We study the class of operations definable from the given operations of an algebra of sets by union, composition, and fixed points; we obtain two theorems on definable operations that give us as special case the regular-equals-recognisable theorem of generalised finite automata theory. Definable operations arise also as the operations computable by charts; by translating into predicate logic, we obtain Manna's formulas for termination and correctness of flowcharts.}
}