No multigraphs

hirnyk — Fri, 22 Apr 2011 20:48:51 Z

As far as I understand it, the GraphTheory package does not deal with multigraphs, as opposed to the networks package. For example, let us add and execute the command
> Edges(G1);

{[1, 2], [1, 8], [2, 3], [2, 9], [3, 1], [3, 4], [4, 2], [4, 5], [5, 3],

[5, 6], [6, 4], [6, 7], [7, 5], [7, 8], [8, 6], [8, 9], [9, 1], [9, 7]}
to your code. We see 18 arcs.

PS. Of course, you can still use the networks package for multigraphs. For example,

> restart;
>with(networks):
> new(G):

> addvertex({1, 2, 3, 4, 5, 6, 7, 8, 9}, G);
1, 2, 3, 4, 5, 6, 7, 8, 9

> addedge([[1, 2], [3, 1], [2, 3], [4, 5], [6, 4], [5, 6], [7, 8], [9, 7], [8, 9], [2, 3], [4, 2], [3, 4], [5, 6], [7, 5], [6, 7], [1, 8], [9, 1], [8, 9], [3, 4], [5, 3], [4, 5], [6, 7], [8, 6], [7, 8], [1, 2], [9, 1], [2, 9]], G);

e1, e2, e3, e4, e5, e6, e7, e8, e9, e10, e11, e12, e13, e14, e15, e16, e17,

e18, e19, e20, e21, e22, e23, e24, e25, e26, e27

> show(G);
table([_Head = table([e18 = 9, e14 = 5, e24 = 8, e19 = 4, e23 = 6, e11 = 2, e10 = 3, e15 = 7, e5 = 4, e27 = 9, e2 = 1, e17 = 1, e4 = 5, e3 = 3, e16 = 8, e7 = 8, e21 = 5, e6 = 6, e26 = 1, e25 = 2, e9 = 9, e20 = 3, e1 = 2, e22 = 7, e13 = 6, e12 = 4, e8 = 7]), _Countcuts = _Countcuts, _Tail = table([e18 = 8, e14 = 7, e24 = 7, e19 = 3, e23 = 8, e11 = 4, e10 = 2, e15 = 6, e5 = 6, e27 = 2, e2 = 3, e17 = 9, e4 = 4, e3 = 2, e16 = 1, e7 = 7, e21 = 4, e6 = 5, e26 = 9, e25 = 1, e9 = 8, e20 = 5, e1 = 1, e22 = 6, e13 = 5, e12 = 3, e8 = 9]), _Ends = table([e18 = {8, 9}, e14 = {5, 7}, e24 = {7, 8}, e19 = {3, 4}, e23 = {6, 8}, e11 = {2, 4}, e10 = {2, 3}, e15 = {6, 7}, e5 = {4, 6}, e27 = {2, 9}, e2 = {1, 3}, e17 = {1, 9}, e4 = {4, 5}, e3 = {2, 3}, e16 = {1, 8}, e7 = {7, 8}, e21 = {4, 5}, e6 = {5, 6}, e26 = {1, 9}, e25 = {1, 2}, e9 = {8, 9}, e20 = {3, 5}, e1 = {1, 2}, e22 = {6, 7}, e13 = {5, 6}, e12 = {3, 4}, e8 = {7, 9}]), _Edges = {e1, e10, e11, e12, e13, e14, e15, e16, e17, e18, e19, e2, e20, e21, e22, e23, e24, e25, e26, e27, e3, e4, e5, e6, e7, e8, e9}, _Econnectivity = _Econnectivity, _Neighbors = table([1 = {2, 3, 8, 9}, 2 = {1, 3, 4, 9}, 3 = {1, 2, 4, 5}, 5 = {3, 4, 6, 7}, 4 = {2, 3, 5, 6}, 7 = {5, 6, 8, 9}, 6 = {4, 5, 7, 8}, 8 = {1, 6, 7, 9}, 9 = {1, 2, 7, 8}]), _Eweight = table([e18 = 1, e14 = 1, e24 = 1, e19 = 1, e23 = 1, e11 = 1, e10 = 1, e15 = 1, e5 = 1, e27 = 1, e2 = 1, e17 = 1, e4 = 1, e3 = 1, e16 = 1, e7 = 1, e21 = 1, e6 = 1, e26 = 1, e25 = 1, e9 = 1, e20 = 1, e1 = 1, e22 = 1, e13 = 1, e12 = 1, e8 = 1]), _Vertices = {1, 2, 3, 4, 5, 6, 7, 8, 9}, _EdgeIndex = table(symmetric, [(4, 5) = {e21, e4}, (5, 6) = {e13, e6}, (3, 5) = {e20}, (3, 4) = {e12, e19}, (2, 3) = {e10, e3}, (1, 9) = {e17, e26}, (6, 8) = {e23}, (2, 9) = {e27}, (4, 6) = {e5}, (5, 7) = {e14}, (7, 8) = {e24, e7}, (1, 8) = {e16}, (8, 9) = {e18, e9}, (1, 3) = {e2}, (2, 4) = {e11}, (7, 9) = {e8}, (1, 2) = {e1, e25}, (6, 7) = {e15, e22}]), _Emaxname = 27, _Vweight = table(sparse, []), _Counttrees = _Counttrees, _Bicomponents = _Bicomponents, _Status = {DIRECTED, MULTIGRAPH}])

PPS. Mathematica 8 does not also deal with multigraphs.

MaplePrimes - answers and comments on Question, How can I make multi-graphs?

No multigraphs