Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Expansion Puzzles   The standard formula that describes the thermal expansion of a solid creates
several puzzles for discerning students. Three puzzles are reviewed, and their
common resolution discussed both conceptually and quantitatively.

6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg