Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-standard Null Lagrangians and Forces in Classical Mechanics   Non-standard Lagrangians are a family of Lagrangians with terms that do not
have clearly discernable energy-like forms. A special class among these
Lagrangians are non-standard null Lagrangians and their gauge functions, which
are used to introduce forces to the laws of dynamics. It is shown that the
non-standard Lagrangian for the law of inertia is Galilean invariant but the
forces resulting from the non-standard null Lagrangian are not Galilean
invariant, except special only time-dependent forces.

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The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat