| \chapter*{Acknowledgements} | |
| I would like to thank my supervisors, Dr. Richard Paige and Dr. Fiona Polack for their invaluable support and feedback throughout the duration of this degree, and my co-authors and colleagues for all the fruitful discussions we have had. | |
| I would also like to express my gratitude to my parents Stavros and Stamatia Kolovos, my partner Jenny Orfanou, and my friends for the support they have offered me throughout those years. | |
| This work has been supported by the European Commission via the ModelWare and ModelPlex EU projects, co-funded under the ``Information Society Technologies'' Sixth Framework Programme (2002-2009). |