Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Large 2-groups of automorphisms of curves with positive 2-rank   Let K be an algebraically closed field of characteristic 2, and let X be a
curve over K of genus g>1 and 2-rank r>0. For 2-subgroups S of the
K-automorphism group Aut(X) of X, the Nakajima bound is |S| < 4g-3. For every
g=2^h+1>8, we construct a curve X attaining the Nakajima bound and determine
its relevant properties: X is a bielliptic curve with r=g, and its
K-automorphism group has a dihedral K-automorphism group of order 4(g-1) which
fixes no point in X. Moreover, we provide a classification of 2-groups S of
K-automorphisms not fixing a point of X and such that |S|> 2g-1.

16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
26
The categories of this paper are: bayes-an
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org