In 1987 S Cappell and J Shaneson constructed an –cobordism from the quaternionic 3–manifold to itself, and asked whether or any of its covers are trivial product cobordism? In this paper we study , and in particular show that its 8–fold cover is the product cobordism from to itself. We reduce the triviality of to a question about the 3–twist spun trefoil knot in , and also relate this to a question about a Fintushel–Stern knot surgery.
"Cappell–Shaneson's $4$–dimensional $s$–cobordism." Geom. Topol. 6 (1) 425 - 494, 2002. https://doi.org/10.2140/gt.2002.6.425