       Re: Mathematica, Graph Theory

• To: mathgroup at smc.vnet.net
• Subject: [mg83345] Re: Mathematica, Graph Theory
• From: mumat <csarami at gmail.com>
• Date: Sat, 17 Nov 2007 05:40:44 -0500 (EST)
• References: <fhh8r9\$9ge\$1@smc.vnet.net>

```This is interesting. It shows that how confusing it can be Mathematica
when it comes to Discrete Mathematics. I think this is quite serious!
Not everyone is into Integration and Calculus these days. I urge
Mathematica folks seriously take a look at Combinatorics/Discrete
Mathematics.

Part of the confusion is from the new GraphPlot function which is
awesome by the way as a graphical tool!!!  gIt is nothing but a graph
drawing package! It creat such a pretty graph. But on the other hand,
has it's own data structure {v_i->v_j}.

Can someone explain to us that why a vertex should have Number
attribute, when we have Label and Weight attributes!!

I think the VertexNumber is the one that creats the problem. When you
use DeleteVertices[h,{1,2}], it reconstruct a new graph with vertices
starting from 1,2,3... That's why

In:= g = DeleteVertices[h, {1, 2}]
Graph:<1,2,Undirected>

DeleteVertices[g, {1, 2}]

Out= Graph:<0,0,Undirected>

Which is an empty graph! Strange!!

I am guessing Wolfram folks are working on it! to unify the
combinatorics package!

```

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