A partition of connected graphs
The electronic journal of combinatorics, Tome 12 (2005)
We define an algorithm $k$ which takes a connected graph $G$ on a totally ordered vertex set and returns an increasing tree $R$ (which is not necessarily a subtree of $G$). We characterize the set of graphs $G$ such that $k(G)=R$. Because this set has a simple structure (it is isomorphic to a product of non-empty power sets), it is easy to evaluate certain graph invariants in terms of increasing trees. In particular, we prove that, up to sign, the coefficient of $x^q$ in the chromatic polynomial $\chi_G(x)$ is the number of increasing forests with $q$ components that satisfy a condition that we call $G$-connectedness. We also find a bijection between increasing $G$-connected trees and broken circuit free subtrees of $G$.
DOI :
10.37236/1968
Classification :
05C30, 05C05, 05C75
Mots-clés : tree, graph invariants, chromatic polynomial
Mots-clés : tree, graph invariants, chromatic polynomial
@article{10_37236_1968,
author = {Gus Wiseman},
title = {A partition of connected graphs},
journal = {The electronic journal of combinatorics},
year = {2005},
volume = {12},
doi = {10.37236/1968},
zbl = {1060.05048},
url = {http://geodesic.mathdoc.fr/articles/10.37236/1968/}
}
Gus Wiseman. A partition of connected graphs. The electronic journal of combinatorics, Tome 12 (2005). doi: 10.37236/1968
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