Throttling for standard zero forcing on directed graphs
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arXiv
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| Auteurs principaux: | , , , , , |
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| Format: | Preprint |
| Publié: |
2020
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| _version_ | 1866916235687493632 |
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| author | Cairncross, Emily Carlson, Joshua Hollander, Peter Kitchen, Benjamin Lopez, Emily Zhuang, Ashley |
| author_facet | Cairncross, Emily Carlson, Joshua Hollander, Peter Kitchen, Benjamin Lopez, Emily Zhuang, Ashley |
| contents | Zero forcing is a process on graphs in which a color change rule is used to force vertices to become blue. The amount of time taken for all vertices in the graph to become blue is the propagation time. Throttling minimizes the sum of the number of initial blue vertices and the propagation time. In this paper, we study throttling in the context of directed graphs (digraphs). We characterize all simple digraphs with throttling number at most $t$ and examine the change in the throttling number after flipping arcs and deleting vertices. We also introduce the orientation throttling interval (OTI) of an undirected graph, which is the range of throttling numbers achieved by the orientations of the graph. While the OTI is shown to vary among different graph families, some general bounds are obtained. Additionally, the maximum value of the OTI of a path is conjectured to be achieved by the orientation of a path whose arcs alternate in direction. The throttling number of this orientation is exactly determined in terms of the number of vertices. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2008_08646 |
| institution | arXiv |
| publishDate | 2020 |
| record_format | arxiv |
| spellingShingle | Throttling for standard zero forcing on directed graphs Cairncross, Emily Carlson, Joshua Hollander, Peter Kitchen, Benjamin Lopez, Emily Zhuang, Ashley Combinatorics 05C15, 05C20, 05C50, 05C57 Zero forcing is a process on graphs in which a color change rule is used to force vertices to become blue. The amount of time taken for all vertices in the graph to become blue is the propagation time. Throttling minimizes the sum of the number of initial blue vertices and the propagation time. In this paper, we study throttling in the context of directed graphs (digraphs). We characterize all simple digraphs with throttling number at most $t$ and examine the change in the throttling number after flipping arcs and deleting vertices. We also introduce the orientation throttling interval (OTI) of an undirected graph, which is the range of throttling numbers achieved by the orientations of the graph. While the OTI is shown to vary among different graph families, some general bounds are obtained. Additionally, the maximum value of the OTI of a path is conjectured to be achieved by the orientation of a path whose arcs alternate in direction. The throttling number of this orientation is exactly determined in terms of the number of vertices. |
| title | Throttling for standard zero forcing on directed graphs |
| topic | Combinatorics 05C15, 05C20, 05C50, 05C57 |
| url | https://arxiv.org/abs/2008.08646 |