Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complex order fractional derivatives in viscoelasticity   We introduce complex order fractional derivatives in models that describe
viscoelastic materials. This can not be carried out unrestrictedly, and
therefore we derive, for the first time, real valued compatibility constraints,
as well as physical constraints that lead to acceptable models. As a result, we
introduce a new form of complex order fractional derivative. Also, we consider
a fractional differential equation with complex derivatives, and study its
solvability. Results obtained for stress relaxation and creep are illustrated
by several numerical examples.

12
The categories of this paper are: nucl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: nlin
31
The categories of this paper are: ao-sci