Important: The networks package has been deprecated.  Use the superseding command GraphTheory[AddVertex] instead.

This routine adds one or more vertices to a graph. The vertex names used are returned as an expression sequence.

To force addvertex() to use a specific weight for a single vertex use the optional argument (eg. weights=3).

If more than one vertex is to be added, they can be presented as a list or set of vertices.  In this case, non-default weights must also be specified as a list of weights as in: addvertex([1, 3], weights=[0, 0], G)

A vertex cannot be a symbol or string beginning with the letter e; these are reserved, by the package, for edge names.

This routine is normally loaded via the command with(networks) but can also be referenced using the full name networks[addvertex](...).