Generalizing forbidden induced subgraph characterizations of high throttling numbers

TL;DR

This paper extends the characterization of graphs with high throttling numbers to various zero forcing variants using abstract color change rules, broadening understanding of graph spread dynamics.

Contribution

It generalizes forbidden induced subgraph characterizations from sum throttling to product and weighted throttling variants under abstract color change rules.

Findings

High throttling graphs characterized by finite forbidden subgraphs

Extension of characterizations to product and weighted throttling

Development of families of color change rules and their properties

Abstract

Zero forcing is a process that models the spread of information throughout a graph as white vertices are forced to turn blue using a color change rule. The idea of throttling, introduced in 2013 by Butler and Young, is to optimize the trade-off between the number of initial blue vertices and the time taken to force all vertices to become blue. The original throttling number of a graph minimizes the sum of these two quantities and the product throttling number minimizes their product. In addition, weighted throttling changes the weights given to these two quantities when minimizing their sum. Since its introduction, throttling has expanded to include many variants of zero forcing. This motivates the study of zero forcing and throttling using abstract color change rules. Recently, it has been shown that the graphs with high (sum) throttling numbers are characterized by a finite family of forbidden induced subgraphs. In this paper, we extend that result to throttling, product throttling, and weighted throttling using abstract color change rules. To this end, we define some important families of color change rules and explore their properties.