An exotic menagerie (Q688321)

In a quest to further demonstrate the perversities that occur in dimension four, the author describes further interesting constructions of uncountably many exotic smooth structures on \(\mathbb{R}^ 4\) and other open 4-manifolds. In particular, the author shows that for any topological 4- manifold \(M\), \(M\)-pt. admits uncountably many smoothings. He then goes on to explicitly construct exotic smooth structures on \(\mathbb{R}^ 4\). Finally, he deftly compares and relates the various constructions of these exotic \(\mathbb{R}^ 4\).