Interactive L systems with almost interactionless behaviour

A restricted version of interactive L systems is introduced. A P2L system is called an essentially growing 2L-systems (e-G2L system) if every length-preserving production is interactionless (context-free). It is shown that the deterministic e-G2L systems can be simulated by codings of propagating interactionless systems, and that this is not possible for the nondeterministic version. Some interesting properties of e-GD2L systems are established, the main result being the decidability of the sequence equivalence problem for them