Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Projektive Geometrie   This is an introduction (in German) to projective geometry by the late Heinz
Lueneburg. Projective spaces are treated as lattices with particular
properties, and finite geometries receive special attention. The final chapters
deal with Segre and Grassmann manifolds.

22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph