Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discrete and continuous description of physical phenomena   The values of many phenomena in the Nature $z$ are determined in some
discrete set of times t_n, separated by a small interval $\Delta t$ (which may
also represent a coordinate, etc.). Let the $z$ value in neighbour point
$t_{n+1}=t_n+\Delta t$ be expressed by the evolution equation as $z(t_{n+1})=
z(t_n+\Delta t)=f(z(t_n))$. This equation gives {\it\underline{a discrete
description}} of phenomenon. Considering phenomena at $t\gg \Delta t$ this
equation is transformed often into the differential equation allowing to
determine $z(t)$ -- {\underline{\it continuous description}}. It is usually
assumed that the continuous description describes correctly the main features
of a phenomenon at values $t>> \Delta t$.
  In this paper I show that the real behavior of some physical systems can
differ strongly from that given by the continuous description. The observation
of such effects may lead to the desire to supplement the original evolutionary
model by additional mechanisms, the origin of which require special
explanation. We will show that such construction may not be necessary -- simple
evolution model can describe different observable effects.
  This text contains no new calculations. Most of the discussed facts are well
known. New is the treatment of the results.

8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int