We show that every closed, simply connected, spin topological 4–manifold except S4
and S2×S2 admits a homologically trivial, pseudofree, locally linear action of Zp for
any sufficiently large prime number p which is nonsmoothable for any possible
smooth structure.
Keywords
nonsmoothable group action, spin
4–manifold, G–index of Dirac operator,
10⁄8–theorem