Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Non-negative Legendrian isotopy in $ST^*M$   It is shown that if the universal cover of a manifold $M$ is an open
manifold, then two different fibres of the spherical cotangent bundle $ST^*M$
cannot be connected by a non-negative Legendrian isotopy. This result is
applied to the study of causality in globally hyperbolic spacetimes. It is also
used to strengthen a result of Eliashberg, Kim, and Polterovich on the
existence of a partial order on $\widetilde{\mathrm{Cont}}_0 (ST^*M)$.

24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph