Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symmetries and constraints in mechanics of continua   In spite of its long history and classical character which goes back even to
d'Alembert and Lagrange, the problems of constraints in mechanics of continua
is still mysterious and full of misunderstandings. Let us mention the problem
of difference between special solutions of unconstrained systems and
constraints dynamics, holonomic and nonholonomic constrained, various versions
of so-called vakonomy, sub-Riemannian structures, servoconstraints, and
programme motion. There are some strange confusions between field theory and
mechanics of continua; many problems call for conceptual cleaning, although
both the mechanics of continua and field theory are formally based on partial
differential equations. The author is deeply indebted to professor Czes\law
Wo\'{z}niak for his help during many years, and deep understanding and support.

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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an