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PseudoDiameter

PseudoDiameter[g]
gives the pseudo-diameter of the undirected graph g, and the two vertices that achieve this diameter.
  • A graph geodesic is a shortest path between two vertices of a graph. The graph diameter is the longest possible length of all graph geodesics of the graph. PseudoDiameter finds an approximate graph diameter. It works by starting from a vertex u, and finds a vertex v that is farthest away from u. This process is repeated by treating v as the new starting vertex, and ends when the graph distance no longer increases. A vertex from the last level set that has the smallest degree is chosen as the final starting vertex u, and a traversal is done to see if the graph distance can be increased. This graph distance is taken to be the pseudo-diameter.
  • If the graph is disconnected, then the diameter and vertices for each connected component are returned.
  • The following option can be given:
AggressiveFalsewhether to make extra effort in finding the optimal graph diameter
Needs["GraphUtilities`"]
The pseudo-diameter of the graph of a square is 2:
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A plot showing the graph with the two vertices of the pseudo-diameter highlighted in red:
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Needs["GraphUtilities`"]
Here is a matrix representation of the graph of a torus:
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The pseudo-diameter of this torus is 7:
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This finds the graph geodesic between vertices 1 and 26, highlighting the graph geodesic in red:
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