Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nonsmoothable involutions on spin 4-manifolds   Let $X$ be a closed, simply-connected, smooth, spin 4-manifold whose
intersection form is isomorphic to $n(-E_8)\bigoplus mH$, where $H$ is the
hyperbolic form.
  In this paper, we prove that for $n$ such that $n\equiv 2 ~{\rm mod} ~4$,
there exists a locally linear pseudofree $\mathbb{Z}_2$-action on $X$ which is
nonsmoothable with respect to any possible smooth structure on $X$.

5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int