Directed Adjacency Lists
===

I have asked this question in a variety of ways, starting with:

> When you have an adjacency list, does order matter? Say I had the adjacency list {1, 2, 5} is that
> equivalent to {2, 1, 5}? Or does order signify something and therefore these two lists are not
> equivalent?

I received several answers including it only matters if the graph is directed and the order signifies something to do with the adjacent nodes arrangement clockwise..? I also was given the opinion that no it does not matter, however he'd prefer it be ordered regarding weights (if used) such as the way the internet is ordered - page ranking algorithm. I don't presume to paraphrase any of these responses accurately although I think I conveyed the gist. Any thoughts are appreciated.

Also, I have refined my question in a way that if answered, I think will give me the exact answer I am after:

> Suppose I have the adjacency matrix for a directed graph:
>
> 0 0 1 0

> 0 0 1 1

> 1 1 0 1

> 0 1 1 0
> 
> I am told the equivalent adjacency lists are as follows and presume my teacher listed it this way
> intentionally rather than some arbitrary reordering - especially as seen in the last list: 
> 
> { 2 } 

> { 2, 3 }

> { 0, 1, 3 }

> { 2, 1 }
>
> The last list is { 2, 1 }! What in the equivalent adjacency matrix alerts me that it should be
> { 2, 1 } rather than { 1, 2 }?
