# networkx.algorithms.distance_regular.is_strongly_regular¶

is_strongly_regular(G)[source]

Returns True if and only if the given graph is strongly regular.

An undirected graph is strongly regular if

• it is regular,

• each pair of adjacent vertices has the same number of neighbors in common,

• each pair of nonadjacent vertices has the same number of neighbors in common.

Each strongly regular graph is a distance-regular graph. Conversely, if a distance-regular graph has diameter two, then it is a strongly regular graph. For more information on distance-regular graphs, see is_distance_regular().

Parameters

G (NetworkX graph) – An undirected graph.

Returns

Whether G is strongly regular.

Return type

bool

Examples

The cycle graph on five vertices is strongly regular. It is two-regular, each pair of adjacent vertices has no shared neighbors, and each pair of nonadjacent vertices has one shared neighbor:

>>> import networkx as nx
>>> G = nx.cycle_graph(5)
>>> nx.is_strongly_regular(G)
True