# isomorphic graphs

• Jun 4th 2011, 01:40 AM
mathgirl1
isomorphic graphs
Hi all, I have been trying to redraw these graphs so I can determine if any of them are isomorphic to each other.

The graphs: ImageShack&#174; - Online Photo and Video Hosting

So there are 6 pairs to look at but I can't redraw them in such a way as to determine if any are isomorphic to one another. I think maybe the second and third are isomorphic but I don't have any drawing to prove it.

Thanks in advance for help help given. (Happy)
• Jun 4th 2011, 02:45 AM
bryangoodrich
Wow, that looks crazy. I've never dealt with stuff like that before. I would go with what I know and try to put it in terms of some sort of algebra, but how to precisely do that translation is foreign to me.

Though, if I were to go that route, I would draw each graph using the same notation (0 through 9). From there I would specify each "joint" in terms of what it connects to. If they're isomorphic, we should see equivalent joints, right? (E.g., 1 is a joint on (2, 7, 9).)
• Jun 4th 2011, 06:30 PM
mathgirl1
Thanks bryangoodrich.

I found that 2 pairs are isomorphic and the rest are not.
• Jun 4th 2011, 06:56 PM
TheEmptySet
Quote:

Originally Posted by bryangoodrich
Wow, that looks crazy. I've never dealt with stuff like that before. I would go with what I know and try to put it in terms of some sort of algebra, but how to precisely do that translation is foreign to me.

Though, if I were to go that route, I would draw each graph using the same notation (0 through 9). From there I would specify each "joint" in terms of what it connects to. If they're isomorphic, we should see equivalent joints, right? (E.g., 1 is a joint on (2, 7, 9).)

Here is what I think you are looking for and how I would approach this problem.

Adjacency matrix - Wikipedia, the free encyclopedia
• Jun 4th 2011, 08:25 PM
bryangoodrich
Yeah, I've never seen anything like this before. I was just trying to conceive of some way to express how the nodes are related that can be compared between graphs. That stuff you found seems to be just the thing! Thanks.