# networkx.algorithms.cuts.boundary_expansion¶

boundary_expansion(G, S)[source]

Returns the boundary expansion of the set S.

The boundary expansion is the quotient of the size of the edge boundary and the cardinality of S. [1]

Parameters
• G (NetworkX graph)

• S (sequence) – A sequence of nodes in G.

Returns

The boundary expansion of the set S.

Return type

number

References

1

Vadhan, Salil P. “Pseudorandomness.” Foundations and Trends in Theoretical Computer Science 7.1–3 (2011): 1–336. <https://doi.org/10.1561/0400000010>