Member since: 2010-01-27 20:27:19
Last Login: 2012-01-10 09:15:34


I'm interested in computer programming, recreational mathematics, and the ancient game of Go (or Baduk, or Wei-qi). I'm not particularly good at any of the above.

Recent blog entries by 8191

Playing whack-a-mole with spammers gets old after a while. Advogato needs at the very least some sort of e-mail confirmation before a new user can post.

6 Feb 2010 (updated 6 Feb 2010 at 17:52 UTC) »

It's way to easy to do hit-and-run spamming on Advogato. It's so easy to automate, I'm surprised that the recentlog isn't completely dominated by spam. The reason it didn't happen yet is probably that the spammers are, well, dumb (evidence: they don't understand nofollow), but one can't rely on security through stupidity forever. Here's a very simple suggestion, which I volunteer to implement in case the Advogato community agrees: instead of asking for a password on registration, create a random password and mail it to the user; the user should then be able to change the password when she logs in. A password reminding mechanism already exists.

6 Feb 2010 (updated 6 Feb 2010 at 16:01 UTC) »

A user becomes a Journeyer with a single certification, from another user who was, in turn, certified by a single user. I see a problem there. There's way too much trust passing through a single vertex in the graph.

Let's put on our Dijkstra hats and think of a solution. Here's one possibility: create a special vertex - let's call it the "sink". Create edges from every vertex in the graph to the sink (the weight of this edge would need to be tweaked a bit). This would add some "leaking" to trust, and help avoid this sort of situation. The actual masters would continue to be masters, but users with few certifications would see their ratings decreased.

An objection to that solution: it would be hard for vertices that are far from the sources to get their ratings raised. But I don't think there are that many "hops" from the sources to vertices that truly deserve trust.

Edit: looks like I misunderstood how the trust metric works. I assumed that mod_virgule would somehow find the sinks in the graph before running the network flow algorithm, but that wouldn't work, since sinks may not even exist (and they probably don't). All vertices are already connected to a single "supersink" - there's no other way. And the problem of users far from the sources not getting certified already exists.

Anyway, there already is a way to attain the proposed "solution", which doesn't even involve code changes: simply decrease the node capacities as a function of source distance; this is defined in config.xml, inside the <caps> tag.

4 Feb 2010 (updated 4 Feb 2010 at 19:08 UTC) »

I like my new bright green color. Thanks everyone!

Wow, looks like the recentlog is a goner. Maybe Advogato needs captchas? It doesn't take a genius to automate this sort of attack.

5 older entries...


8191 certified others as follows:

  • 8191 certified redi as Master
  • 8191 certified raph as Master
  • 8191 certified ncm as Master
  • 8191 certified sye as Journeyer
  • 8191 certified chalst as Journeyer
  • 8191 certified zanee as Journeyer
  • 8191 certified ittner as Apprentice

Others have certified 8191 as follows:

  • redi certified 8191 as Apprentice
  • ncm certified 8191 as Apprentice
  • sye certified 8191 as Journeyer
  • chalst certified 8191 as Apprentice
  • zanee certified 8191 as Apprentice
  • ittner certified 8191 as Apprentice

[ Certification disabled because you're not logged in. ]

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