On the structure of derivations in deterministic ET0L systems

摘要

This paper investigates the structure of derivations in deterministic ET0L systems. The main theorem says that in a deterministic ETOL system each derivation of a long enough word of a special kind (the so-called f-random word) has a rather strong combinatorial structure. In fact the main result of this paper is essential for proving some useful properties of ET0L languages which is demonstrated in a number of papers.