Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Simply-connected, spineless 4-manifolds   We construct infinitely many smooth 4-manifolds which are homotopy equivalent
to $S^2$ but do not admit a spine, i.e., a piecewise-linear embedding of $S^2$
which realizes the homotopy equivalence. This is the remaining case in the
existence problem for codimension-2 spines in simply-connected manifolds. The
obstruction comes from the Heegaard Floer $d$ invariants.

37
The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
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The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int