PreprintCC BY-NC-ND 4.0HAL
Proof of the Göbel-Veldman conjecture on diametrical graphs
Abstract
A graph is called noncircular if it is not a cycle. A nontrivial connected graph G of diameter d is called diametrical if, for every vertex v of G, there exists a unique vertex at distance d from v. In 1986, Göbel and Veldman conjectured that the order of a noncircular diametrical graph of diameter d is at least 4(d -1). We prove this conjecture. Diametrical graphs were called even graphs by Gobel and Veldman.
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BibTeX
@misc{zhan2026proof,
title = {{Proof of the Göbel-Veldman conjecture on diametrical graphs}},
author = {Xingzhi Zhan},
howpublished = {HAL},
year = {2026},
month = aug,
url = {https://hal.science/hal-05746382v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Proof of the Göbel-Veldman conjecture on diametrical graphs
AU - Xingzhi Zhan
PY - 2026
DA - 2026/08/30
PB - HAL
UR - https://hal.science/hal-05746382v1
AB - A graph is called noncircular if it is not a cycle. A nontrivial connected graph G of diameter d is called diametrical if, for every vertex v of G, there exists a unique vertex at distance d from v. In 1986, Göbel and Veldman conjectured that the order of a noncircular diametrical graph of diameter d is at least 4(d -1). We prove this conjecture. Diametrical graphs were called even graphs by Gobel and Veldman.
ER -