A Biologically Motivated Extension of ALGOL-like Languages

E0L-languages arose in the study of developmental systems in biology. In this paper we characterize E0L-languages in terms of ALGOL-like equations. We show that by allowing finite rather than empty sets as the starting points in the recursive process for obtaining a language defined by the ALGOL-like equations, we get exactly the family of E0L-languages. Corollaries obtained include a normal form theorem, the elimination of e -rules for E0L-systems and a comparison with the extended definable languages.