Zero forcing is a combinatorial game played on graphs that can be used to model the spread of information with repeated applications of a color change rule. In general, a zero forcing parameter is the minimum number of initial blue vertices that are needed to eventually color every vertex blue with a given color change rule. Furthermore, the throttling number minimizes the sum of the number of initial blue vertices and the time taken for all vertices to become blue. In 2013, Barioli et al. added a new rule, called hopping, to existing color change rules in order to demonstrate that the minor monotone floor of various zero forcing parameters is itself, a zero forcing parameter. In this paper, we examine the hopping color change rule independently from the other classic rules. Specifically, we study the hopping forcing number and the hopping throttling number. We investigate the ways in which these numbers are related to various graph theory parameters (such as vertex connectivity and independence number) as well as other zero forcing parameters.

Letters to the Editors 905 medium containing blood. For this reason we preferred to test our strains after growth on blood agar base. Precise details of Severin's chromogenic cephalosporin substrate method were not stated. To the best of our knowledge, antibiotic therapy had not been given to the four patients from whom ,B-lactamase producing strains were isolated. Clearly, the possibility of transfer of plasmids deter-

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