Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A proof of the convexity of the set of lamination parameters   In this paper we show that the proof of the convexity of the set of
lamination parameters given by J.L. Grenestedt and P. Gudmundson, which is
extensively cited in the literature, is not correct. We give a proof of the
convexity of this set when the class of functions which gives the layup angle
as a function of the through-the-thickness coordinate is the set of step
functions.

6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ