Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Linear Spaces of Symmetric Matrices with Non-Maximal Maximum Likelihood
  Degree   We study the maximum likelihood degree of linear concentration models in
algebraic statistics. We relate the geometry of the reciprocal variety to that
of semidefinite programming. We show that the Zariski closure in the
Grassmanian of the set of linear spaces that do not attain their maximal
possible maximum likelihood degree coincides with the Zariski closure of the
set of linear spaces defining a projection with non-closed image of the
positive semidefinite cone. In particular, this shows that this closure is a
union of coisotropic hypersurfaces.

18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con