Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On a Convex Set with Nondifferentiable Metric Projection   A remarkable example of a nonempty closed convex set in the Euclidean plane
for which the directional derivative of the metric projection mapping fails to
exist was constructed by A. Shapiro. In this paper, we revisit and modify that
construction to obtain a convex set with smooth boundary which possesses the
same property.

15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg