I am grateful to my supervisor Erzsébet Csuhaj-Varjú, who introduced me to the field of eco-grammar systems. Without her help and advice this work would not have been written.
I would like to thank SZTAKI, the Computer and Automation Research Institute of the Hungarian Academy of Sciences, for giving me the possibility of working there.
My thanks also go to my colleagues at the Department of Computer Science and Information Theory at the Budapest University of Technology and Economics for providing such a pleasant working atmosphere.
Special thanks to Dániel Marx for helping so much in the final phase of the work.