GrayCodeKSubsets[l, k] generates k-subsets of l in Gray code order.

GrayGraph returns a 3-regular, 54-vertex graph that is edge-transitive but not vertex-transitive\[LongDash]the smallest known such example.

GroetzschGraph returns the smallest triangle-free graph with chromatic number 4. This is identical to MycielskiGraph[4].

HamiltonianPath[g] finds a Hamiltonian path in graph g if one exists. HamiltonianPath[g, All] gives all Hamiltonian paths of graph g.

HasseDiagram[g] constructs a Hasse diagram of the relation defined by directed acyclic graph g.

HeawoodGraph returns a smallest (6, 3)-cage, a 3-regular graph with girth 6.

HighlightedEdgeColors is an option to Highlight that determines which colors are used for the highlighted edges.

HighlightedEdgeStyle is an option to Highlight that determines how the highlighted edges are drawn.

HighlightedVertexColors is an option to Highlight that determines which colors are used for the highlighted vertices.

HighlightedVertexStyle is an option to Highlight that determines how the highlighted vertices are drawn.