VertexContract

VertexContract[g,{v1,v2,…}] contracts a collection of vertices v1, v2, … into a single vertex of the graph g.

VertexContract[g,{{v1,v2,…},…}] contracts several collections of vertices.

VertexContract[{v->w,…},…] uses rules v->w to specify the graph g.

Examples

Contract two vertices in a graph:

VertexContract[CompleteGraph[5], {1, 2}]

Please visit the official Wolfram Language Reference for more details.