The -triangular
honeycomb bishop graph
(DeMaio and Tran 2013), called the hex bishop graph and
denoted
by Wagon (2014), is a graph consisting of vertices
on a triangular honeycomb board with
vertices along each side, where vertices
are connected by a graph edge if they lie on the same
or
diagonal line of the chessboard (DeMaio and Tran 2013, Wagon 2014). The graphs
for
and 4 are illustrated above.
Note the moves considered in this definition differ from those allowed by the bishop piece in Gliński's hexagonal chess (Gliński 1973).
Rather surprisingly, the -triangular honeycomb bishop graph is isomorphic to the
black bishop graph (Wagon 2014). Other special
cases are summarized in the following table.
| isomorphic graph | |
| 1 | singleton graph |
| 2 | path
graph |
| 3 | cis-square with two triangles |
The -triangular
honeycomb bishop graph has vertex count and edge
count given by
|
(1)
| |||
|
(2)
| |||
|
(3)
|
where
is a binomial coefficient.
Triangular honeycomb bishop graphs are black bishops, class 1, claw-free, connected, line, nongeometric, perfect, quadratically embeddable, traceable, and weakly perfect.
Triangular honeycomb bishop graphs are implemented in the Wolfram Language as GraphData["TriangularHoneycombBishop", n
].