SOFSEM 2007: Theory and Practice of Computer Science - Leeuwen, Jan; Hoek, Wiebe; Italiano, Giuseppe F.; Meinel, Christoph; PlÃ¡Å¡il, FrantiÅ¡ek; Sack, Harald; Hoek, Wiebe van der; van der Hoek, Wiebe (Springer Berlin Heidelberg, 2007)