Christopher H. Broadbent, Stefan Göller. On Bisimilarity of Higher-Order Pushdown Automata: Undecidability at Order Two. In Deepak D'Souza, Telikepalli Kavitha, Jaikumar Radhakrishnan, editors, IARCS Annual Conference on Foundations of Software Technology and Theoretical Computer Science, FSTTCS 2012, December 15-17, 2012, Hyderabad, India. Volume 18 of LIPIcs, pages 160-172, Schloss Dagstuhl - Leibniz-Zentrum fuer Informatik, 2012. [doi]
Abstract is missing.