One of the useful results concerning EOL languages states that a language is an EOL language if and only if it is a coding of a OL language. In this paper we refine this result by demonstrating that there exist EOL languages that are not codings of languages that are generated by propogating OL systems with finite axiom sets. This solves Problem 10 from the “L SYSTEMS PROBLEM BOOK ‘75” (see ).
Ehrenfeucht, Andrzej and Rozenberg, Grzegorz, "EOL Languages Are Not Codings of FPOL Languages ; CU-CS-098-76" (1976). Computer Science Technical Reports. 96.