Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stochastic model for the vocabulary growth in natural languages   We propose a stochastic model for the number of different words in a given
database which incorporates the dependence on the database size and historical
changes. The main feature of our model is the existence of two different
classes of words: (i) a finite number of core-words which have higher frequency
and do not affect the probability of a new word to be used; and (ii) the
remaining virtually infinite number of noncore-words which have lower frequency
and once used reduce the probability of a new word to be used in the future.
Our model relies on a careful analysis of the google-ngram database of books
published in the last centuries and its main consequence is the generalization
of Zipf's and Heaps' law to two scaling regimes. We confirm that these
generalizations yield the best simple description of the data among generic
descriptive models and that the two free parameters depend only on the language
but not on the database. From the point of view of our model the main change on
historical time scales is the composition of the specific words included in the
finite list of core-words, which we observe to decay exponentially in time with
a rate of approximately 30 words per year for English.

7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org