K-vertex-connected graph


K-vertex-connected graph

In graph theory, a graph "G" with vertex set "V(G)" is said to be "k"-vertex-connected (or "k"-connected) if G setminus X is connected for all X subseteq V(G) with left| X ight| < k. In plain English, a graph is "k"-connected if the graph remains connected when you delete fewer than "k" vertices from the graph. Or, equivalently (owing to Menger's theorem), a graph is "k"-connected if any two of its vertices can be joined by "k" independent paths Harv|Diestel|2005| p=55.

A 1-vertex-connected graph is connected, while a 2-vertex-connected graph is said to be biconnected.

If a graph "G" is "k"-vertex-connected, and "k" < |"V(G)"|, then k le delta(G), where "δ(G)" is the minimum degree of any vertex v in V(G). This fact is clear since deleting all neighbors of a vertex of minimum degree will disconnect that vertex from the rest of the graph.

The 1-skeleton of any "k"-dimensional convex polytope forms a k-vertex-connected graph (Balinski 1961). As a partial converse, Steinitz showed that any 3-vertex-connected planar graph forms the skeleton of a convex polyhedron.

References

*cite journal
author = Balinski, M. L.
title = On the graph structure of convex polyhedra in "n"-space
journal = Pacific Journal of Mathematics
volume = 11
issue = 2
year = 1961
pages = 431–434
url = http://www.projecteuclid.org/Dienst/UI/1.0/Summarize/euclid.pjm/1103037323

*.

See also

* k-edge-connected graph
* Connectivity (graph theory)
* Menger's theorem
* Structural cohesion


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