Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Warmth and connectivity of neighborhood complexes of graphs   In this paper we study a pair of numerical parameters associated to a graph
$G$. One the one hand, one can construct $\text{Hom}(K_2, G)$, a space of
homomorphisms from a edge $K_2$ into $G$ and study its (topological)
connectivity. This approach dates back to the neighborhood complexes introduced
by Lov\'asz in his proof of the Kneser conjecture. In another direction
Brightwell and Winkler introduced a graph parameter called the warmth
$\zeta(G)$ of a graph $G$, based on asymptotic behavior of $d$-branching walks
in $G$ and inspired by constructions in statistical physics. Both the warmth of
$G$ and the connectivity of $\text{Hom}(K_2,G)$ provide lower bounds on the
chromatic number of $G$.
  Here we seek to relate these two constructions, and in particular we provide
evidence for the conjecture that the warmth of a graph $G$ is always less than
three plus the connectivity of $\text{Hom}(K_2, G)$. We succeed in establishing
a first nontrivial case of the conjecture, by showing that $\zeta(G) \leq 3$ if
$\text{Hom}(K_2,G)$ has an infinite first homology group. We also calculate
warmth for a family of `twisted toroidal' graphs that are important extremal
examples in the context of $\text{Hom}$ complexes. Finally we show that
$\zeta(G) \leq n-1$ if a graph $G$ does not have the complete bipartite graph
$K_{a,b}$ for $a+b=n$. This provides an analogue for a similar result in the
context of $\text{Hom}$ complexes.

6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph