Siu Man Chan, Massimo Lauria, Jakob Nordström, Marc Vinyals. Hardness of Approximation in PSPACE and Separation Results for Pebble Games. In Venkatesan Guruswami, editor, IEEE 56th Annual Symposium on Foundations of Computer Science, FOCS 2015, Berkeley, CA, USA, 17-20 October, 2015. pages 466-485, IEEE, 2015. [doi]
Abstract is missing.