Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Expansions which introduce no new open sets   We consider the question of when an expansion of a topological structure has
the property that every open set definable in the expansion is definable in the
original structure. This question is related to and inspired by recent work of
Dolich, Miller and Steinhorn on the property of having o-minimal open core. We
answer the question in a fairly general setting and provide conditions which in
practice are often easy to check. We give a further characterisation in the
special case of an expansion by a generic predicate.

28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess