Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Betweenness of partial orders   We construct a monadic second-order sentence that characterizes the ternary
relations that are the betweenness relations of finite or infinite partial
orders. We prove that no first-order sentence can do that. We characterize the
partial orders that can be reconstructed from their betweenness relations. We
propose a polynomial time algorithm that tests if a finite relation is the
be-tweenness of a partial order.

35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an