On Wed, Sep 16, 2009 at 11:05 AM, Matthew Toseland <t...@amphibian.dyndns.org> wrote: > On Tuesday 15 September 2009 01:51:32 Evan Daniel wrote: >> On Mon, Sep 14, 2009 at 3:29 PM, Evan Daniel <eva...@gmail.com> wrote: >> > There are several confounding factors. First, the data aren't >> > independent; there should be local clustering, and I seem to have >> > double-counted the links to my node (18 out of 353 data points) (links >> > between my peers would also be double-counted, but there don't appear >> > to be any). Second, there's the bandwidth issue: some of my peers are >> > faster than others, as can be seen from their varied number of FOAF >> > locations. Peers with more FOAF locations will receive more traffic, >> > in (rough) proportion to the number of FOAF locations they have. I'm >> > uncertain how the link length distribution should respond; perhaps a >> > link to a peer should be counted n times, where n is the number of >> > FOAF locations it advertises? Or perhaps not; figuring that out would >> > take some theoretical work I haven't done. On average, across a large >> > number of nodes / links, that effect should go away. Third, we must >> > be wary of observer bias: nodes that connect to other nodes are more >> > likely to be observed by a random sample of nodes. This will impact >> > FOAF link length counting, but not local link length counting. >> >> Sorry, there are some inaccuracies above: >> My node had 16 peers in that dataset (not 18). There are 33 duplicate >> locations in the full listing. 15 of those represent duplicates of my >> node's location. The remaining 18 are repeated counts of nodes other >> than mine: either my node connected to nodes A and B, which are >> connected to each other (and therefore each counted twice), or my node >> connected to nodes A and B, both of which are connected to a common >> node C (which isn't connected to my node). > > So some of your peers *do* connect to each other? >
There are 353 locations listed in my data. That's all the locations reported in the location column of all the rows on my connections to strangers page. Of those, 16 are my location (I have 16 peers, each of which reports my location as one of its FOAF locations). There are 302 locations that appear only once, and 18 locations that appear more than once (320 total unique locations, including my node's location). Of the locations that appear more than once, 16 appear exactly twice, 1 appears 3 times, and my location appears 16 times. Of the 16 locations that appear twice, 3 of them are my peers' locations; that is, a connection that exists between two nodes that are connected to my node. The remaining 13 doubled locations and the one tripled location are nodes that are not connected to my node. (This is a topological impossibility; my node cannot be connected to A, B, and C, each of which is connected to exactly one of the other two. I presume this means there was a recent change in the local topology that had not yet updated at the time I took the data.) This is suggestive of some local clustering; it's hard to conclude whether it is an appropriate amount without both a more detailed analysis (non-constant degree makes it mildly complex, for starters) and an estimate of network size. That was done by a spreadsheet-assisted manual count; it's possible I made a mistake. If you're concerned about the details, I suggest both checking my math and collecting data from multiple nodes. (The full list of locations is available in the spreadsheet.) Evan Daniel _______________________________________________ Devl mailing list Devl@freenetproject.org http://emu.freenetproject.org/cgi-bin/mailman/listinfo/devl
