@inbook{31da21505d7147bebf449f88f57331eb,
title = "An Infinite Sequence of Full AFL-structures, Each of Which Possesses an Infinite Hierarchy",
abstract = "We investigate different sets of operations on languages which result in corresponding algebraic structures, viz. in different types of full AFL{\textquoteright}s (full Abstract Family of Languages). By iterating control on ETOL-systems we show that there exists an infinite sequence Cm(m⩾1) of classes of such algebraic structures (full AFL-structures): each class is a proper superset of the next class (Cm ⊃ Cm +1). In turn each class Cm contains a countably infinite hierarchy, i.e. a countably infinite chain of language families Km,n (n⩾1) such that (i) each Km,n is closed under the operations that determine C m and (ii) each K m,n is properly included in the next one: Km,n ⊂ Km,n+1.",
author = "Asveld, {Peter R.J.}",
year = "2001",
doi = "10.1007/978-94-015-9634-3_15",
language = "English",
isbn = "978-90-481-5607-8",
pages = "175--186",
editor = "Carlos Martin-Vide and Victor Mitrana",
booktitle = "Where Mathematics, Computer Science, Liguistics and Biology Meet",
publisher = "Kluwer",
address = "Netherlands",
}