A Pumping Lemma for Collapsible Pushdown Graphs of Level 2
Alexander Kartzow · DROPS (Schloss Dagstuhl – Leibniz Center for Informatics) · 2011
We present a pumping lemma for the class of collapsible pushdown graphs of level 2. This pumping lemma even applies to epsilon-contractions of level 2 collapsible pushdown graphs. Our pumping lemma also improves the bounds of Hayashi's pumping lemma for indexed languages.