Quasi-Cubic Graph
A quasi-cubic graph is a quasi-regular graph, i.e., a graph such that the vertex
degree of every vertex is the same except for a single vertex
whose vertex degree is
(Szádoczki et al. 2022), with
. By the handshaking
lemma, such a graph necessarily has odd graph order: if it has
vertices, the sum
of its vertex degrees is
and must be even, so
is odd.
For ,
7, 9, ..., the numbers of quasi-cubic graphs are 1, 4, 28, 214, 1999, 22186, ...
(OEIS A398638). The corresponding numbers of
connected quasi-cubic graphs are 1, 4, 27, 208,
1958, 21879, ... (OEIS A398639). Of the quasi-cubic
graphs on 19 vertices, 28526 are disconnected.
The sole disconnected quasi-cubic graph through nine vertices
is the graph disjoint union
, whose components
are the wheel graph
and the tetrahedral graph
. Examples are illustrated above and
are summarized in the table below.
| quasi-cubic graphs | |
| 5 | wheel graph |
| 7 | Harary graph |
| 9 | Harary
graph |
See also
Cubic Graph, Handshaking Lemma, Quasi-Quintic Graph, Quasi-Regular Graph, Regular GraphExplore with Wolfram|Alpha
References
Szádoczki, Z.; Bozóki, S.; and Tekile, H. A. "Filling in Pattern Designs for Incomplete Pairwise Comparison Matrices: (Quasi-)Regular Graphs with Minimal Diameter." Omega 107, 102557, 2022. https://doi.org/10.1016/j.omega.2021.102557.Sloane, N. J. A. Sequences A398638 and A398639 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
Quasi-Cubic GraphCite this as:
Weisstein, Eric W. "Quasi-Cubic Graph." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Quasi-CubicGraph.html