Furthermore, I would like to thank my colleagues Svitlana Voronkova and Bartosz Gebka who were steady sources of inspiration and discussion. I also appreciate the excellent cooperation in joint projects with both of them. Other colleagues at European University Viadrina who contributed to the success of my work were among others Katarzyna Grinberg, Tomasz Wi´ sniewski, Piotr Korczak, and Dobromi lSerwa. As I presented the papers included in this thesis on several conferences, I obtained valuable insights on the subjects of interest. Beyond this, coop- erations with other researchers from different universities boosted my work considerably. Among those I would like to thank in particular are Beni Lauterbach, Kenneth Kim,.
