EasterSunday[year] gives the date of Easter Sunday in the Gregorian calendar system.

AcyclicQ[g] yields True if graph g is acyclic.

AddVertex[g] adds one disconnected vertex to graph g. AddVertex[g, v] adds to g a vertex with coordinates specified by v.

ApproximateVertexCover[g] produces a vertex cover of graph g whose size is guaranteed to be within twice the optimal size.

Automorphisms[g] gives the automorphism group of the graph g.

BipartiteQ[g] yields True if graph g is bipartite.

ChromaticNumber[g] gives the chromatic number of the graph, which is the fewest number of colors necessary to color the graph.

ChvatalGraph returns a smallest triangle-free, 4-regular, 4-chromatic graph.

CircularEmbedding[n] constructs a list of n points equally spaced on a circle. CircularEmbedding[g] embeds the vertices of g equally spaced on a circle.

CliqueQ[g, c] yields True if the list of vertices c defines a clique in graph g.