Guilbault–Tinsley question on Z-compactifiability and pseudo-collarability

Guilbault and Tinsley asked whether a $\mathcal{Z}$-compactifiable open manifold can fail to be pseudo-collarable. The question concerns separating these two end properties through an explicit open four-manifold.

August 25, 2026 claimed affirmative answer

A preprint attributed to Shijie Gu claims that the specified Kwasik–Schultz manifolds are $\mathcal{Z}$-compactifiable but not pseudo-collarable, thereby answering the question affirmatively. The latest report says this supplies an explicit open four-manifold example, but the claim remains unverified.

Current status (as of August 2026): The question has a claimed affirmative answer via specified Kwasik–Schultz examples, but the result remains unverified.