Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Softer than soft: diving into squishy granular matter   Softer than soft, squishy granular matter is composed of grains capable of
significantly changing their shape (typically larger than 10% of deformation)
without tearing or breaking. Because of the difficulty to test these materials
experimentally and numerically, such a family of discrete systems remains
largely ignored in the granular matter physics field despite being commonly
found in nature and industry. Either from a numerical, experimental, or
analytical point of view, the study of highly deformable granular matter
involves several challenges covering, for instance: ($i$) the need to include a
large diversity of grain rheology, ($ii$) the need to consider \dc{large
material} deformations, and ($iii$) the analysis upon the effects the large
body distortion has on the global scale. In this article, we propose a thorough
definition of these squishy granular systems, and we summarize the upcoming
challenges in their study.

5
The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: econ
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga