[Tech] Position randomization

[Michael Rogers]

vive wrote:
> Note that this is a natural part
> of running the swapping algorithms and having some tight-connected neighborhoods.

I see - so we're talking about clusters that already exist in the
topology being reproduced in the locations; would you also expect
location clustering to occur in opennet, where there are presumably no
tight clusters in the topology?

> Once in a while the randomized position from a newbie node will fit well enough
> with the later group, so some nodes in that cluster will want to consume (with
> swapping) the newbie addresses if it lets them specialize even further (brings
> them closer in keyspace, due to the nature of the swapping algorithm).

That would make sense if there were only a single cluster of long-lived
nodes. But haven't we always assumed that the social network contains
many clusters, with a Kleinberg-like overall structure? If that's the
case, there are not only strong ties pulling each cluster together -
there are also weak ties between clusters, stretching the clusters out.
The nodes in each cluster shouldn't become more and more tightly
clustered, even if they have a constant supply of suitable locations,
because the inter-cluster ties should counterbalance the intra-cluster
ties. If that's not happening, it seems like the problem is with the
topology (too few inter-cluster links) rather than with churn.

> Using the current locations is not the same as generating the Kleinberg model
> from the beginning.

Really? The connection probabilities are independent, so I would have
thought that if you removed a node and replaced it with a new node, the
new node's links would be independent of the existing links (and thus
could be generated using just the current locations).

Cheers,
Michael