Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Pseudo-isotopies and diffeomorphisms of 4-manifolds   A diffeomorphism $f$ of a compact manifold $X$ is pseudo-isotopic to the
identity if there is a diffeomorphism $F$ of $X\times I$ which restricts to $f$
on $X\times 1$, and which restricts to the identity on $X\times 0$ and
$\partial X\times I$. We construct examples of diffeomorphisms of 4-manifolds
which are pseudo-isotopic but not isotopic to the identity. To do so, we
further understanding of which elements of the "second pseudo-isotopy
obstruction", defined by Hatcher and Wagoner, can be realised by
pseudo-isotopies of 4-manifolds. We also prove that all elements of the first
and second pseudo-isotopy obstructions can be realised after connected sums
with copies of $S^2\times S^2$.

16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess