Validating Documents of Web-based Metalanguages Using Semantic Rules

To my family and all who have helped me on my path. Foreword It has been a long and challenging journey: I have finally written my PhD dissertation. I started my PhD studies back in 2003. After finishing the three year PhD program my publication activities halted for several years. I started working, which consumed most of my time and didn't have enough energy left after a long day's work. After several years of absence from the research community I decided to pick up where I left off and pursue my PhD again. I started searching for an updated research area and that led me to validation. I would like to thank Prof. Tibor Gyimóthy and Ferenc Havasi for their collaboration, guidance and help. Furthermore I am extremely grateful for the extended support of my brother and parents along with my good friends Péter Rosztóczy, Ottó Vas and Gergely Molnár for believing in me and persistently guiding me through the tough times and never giving up on me. I would also like to thank László Szabó for his help and coaching as well as Paulina Nagy for her help in proofreading. I hope my dissertation will inspire others to hang on and finish what they started, since at the end it does provide a great feeling of accomplishment.