Computing topological indices by pulling a few strings

A thread in a graph $G$ is any maximal connected subgraph induced by a set of vertices of degree $2$ in $G$. A string in $G$ is a subgraph induced by a thread and the vertices adjacent to it. A graph $G$ consists of $s$ strings if it can be represented as a union of $s$ strings so that any two strings have at most two vertices in common. In this paper we compute several recently introduced graph invariants for all graphs that consist of at most three strings.