Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Integrating Lie algebroids via stacks   Lie algebroids can not always be integrated into Lie groupoids. We introduce
a new object--``Weinstein groupoid'', which is a differentiable stack with
groupoid-like axioms. With it, we have solved the integration problem of Lie
algebroids. It turns out that every Weinstein groupoid has a Lie algebroid and
every Lie algebroid can be integrated into a Weinstein groupoid.

14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int