## Abstract

A well-known result by Hedetniemi states that for every graph G there is a graph H whose center is G. We extend this result by showing under which conditions there exists, for a given graph G in which each vertex v has an integer label ℓ (v), a graph H containing G as an induced subgraph such that the eccentricity, in H, of every vertex v of G equals ℓ(v). Such a labelled graph G is said to be eccentric, and strictly eccentric if there exists such a graph H such that no vertex of H -G has the same eccentricity in H as any vertex of G. We find necessary and sufficient conditions for a labelled graph to be eccentric and for a forest to be eccentric or strictly eccentric in a tree.

Original language | English |
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Journal | Discussiones Mathematicae Graph Theory |

Early online date | 19 Feb 2021 |

DOIs | |

Publication status | E-pub ahead of print - 19 Feb 2021 |

Externally published | Yes |

## Keywords

- Distance
- Eccentricity
- Subgraph
- Tree

## ASJC Scopus subject areas

- Applied Mathematics
- Discrete Mathematics and Combinatorics