4 papers
Approximate Graph Colouring and Crystals
Lorenzo Ciardo, Stanislav Živný
We show that approximate graph colouring is not solved by any level of the affine integer programming (AIP) hierarchy. To establish the result, we translate the problem of exhibiti…
Perron value and moment of rooted trees
Lorenzo Ciardo
The Perron value of a rooted tree has a central role in the study of the algebraic connectivity and characteristic set, and it can be considered a weight of spectral nat…
On Kemeny's constant for trees with fixed order and diameter
Lorenzo Ciardo, Geir Dahl, Steve Kirkland
Kemeny's constant of a connected graph is a measure of the expected transit time for the random walk associated with . In the current work, we consider the case when…
The Braess' Paradox for Pendant Twins
Lorenzo Ciardo
The Kemeny's constant of a connected undirected graph can be interpreted as the expected transit time between two randomly chosen vertices for the Markov chain associate…