NoPerfectMatchingGraph returns a connected graph with 16 vertices that contains no perfect matching.

NormalDashed is a value that the option EdgeStyle can take on in the graph data structure or in ShowGraph.

NumberOf2Paths[g, v] returns a sorted list that contains the number of paths of length 2 to different vertices of g from v.

OctahedralGraph returns the graph corresponding to the octahedron, a Platonic solid.

One is a tag used in several functions to inform the functions that only one object need be considered or only one solution be produced, as opposed to all objects or all ...

Optimum is a value that the option Algorithm can take on when used in functions VertexColoring and VertexCover.

Parent is a tag used as an argument to the function AllPairsShortestPath in order to inform this function that information about parents in the shortest paths is also wanted.

PseudographQ[g] yields True if graph g is a pseudograph, meaning it contains self-loops.

RandomComposition[n, k] constructs a random composition of integer n into k parts.

RandomKSubset[l, k] gives a random subset of set l with exactly k elements.