Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gerbert of Aurillac: astronomy and geometry in tenth century Europe   Gerbert of Aurillac was the most prominent personality of the tenth century:
astronomer, organ builder and music theoretician, mathematician, philosopher,
and finally pope with the name of Silvester II (999-1003). Gerbert introduced
firstly the arabic numbers in Europe, invented an abacus for speeding the
calculations and found a rational approximation for the equilateral triangle
area, in the letter to Adelbold here discussed. Gerbert described a semi-sphere
to Constantine of Fleury with built-in sighting tubes, used for astronomical
observations. The procedure to identify the star nearest to the North celestial
pole is very accurate and still in use in the XII century, when "Computatrix"
was the name of Polaris. For didactical purposes the Polaris would have been
precise enough and much less time consuming, but here Gerbert was clearly
aligning a precise equatorial mount for a fixed instrument for accurate daytime
observations. Through the sighting tubes it was possible to detect equinoxes
and solstices by observing the Sun in the corresponding days. The horalogium of
Magdeburg was probably a big and fixed-mount nocturlabe, always pointing the
star near the celestial pole.

26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con