Ricerc@Sapienza

A graph G=(V,E) is a pairwise compatibility graph (PCG) if there exists an edge-weighted tree T and two non-negative real numbers dmin and dmax, dmin≤dmax, such that each node u∈V is uniquely associated to a leaf of T and there is an edge (u,v)∈E if and only if dmin≤dT(u,v)≤dmax, where dT(u,v) is the sum of the weights of the edges on the unique path PT(u,v) from u to v in T. Understanding which graph classes lie inside and which ones outside the PCG class is an important issue.

In-service wheel-rail contact force measurements are increasingly being performed with both on-board and wayside systems for various purposes, such as identifying problems on single vehicles (overloading and unbalance, wheel flats etc.) and enabling predictive maintenance of components. Such a wealth of measurements can be expected not only to fulfil their original purposes, but also to steadily fill in vehicle-track interaction knowledge gaps if properly exploited - e.g. with a big-data approach.