X-Message-Number: 23946
Date: 21 Apr 2004 19:11:04 -0000
From: "Kevin Q. Brown" <>
Subject: CryoNet Spam(mer) Filtering

In CryoNet message #23901 (CryoNet Spam Filtering) I described
the problem of repeated abuse of CryoNet posting privileges **
by one of CryoNet's subscribers and promised to provide improved
spam filtering to Cryonet.  Messages that trigger the filter will
be excised from the digests that all subscribers receive, but will
not be removed from the archives.

The goal of this filter is to discourage repeated abuse of CryoNet.
Thus, people who usually post relevant messages, but occasionally
stray off-topic, should not have even their off-topic messages
filtered out by a spam filter.  CryoNet usually has some noise,
as well as interesting messages.  I'm not planning to change that.
The filter thus will be reputation-based rather than content-based.
(Perhaps I should have called it a spammer filter rather than a
spam filter.)  Repeated inappropriate postings will reduce the
poster's reputation score sufficiently that subsequent postings
will be excised from the daily digests.  I plan to use time-based
discounting for the reputation calculation, much like one computes
the "net present value" of an investment.  As a result, a low
reputation score will not be permanent; it will be more like a
temporary penalty box for bad behavior.

This system will be implemented in multiple stages.  The first
stage will introduce a rating system for individual postings.
Each CryoNet subscriber will be able to rate the messages
in a daily digest.  After a few weeks of accumulating those
ratings, the software will start updating reputation scores
for the posters of those messages.  Eventually the reputation
scores will be used for spam(mer) filtering.

Soon the CryoNet daily digest will include, after each message,
a hyperlink for rating that message.  Expect some fine-tuning of
this system as we gain experience with it.  If all goes well,
it will encourage postings that CryoNet readers value while
discouraging postings that they do not and, in particular,
remove from the digests those messages most likely to be spam.

  Kevin Q. Brown

 ** I neglected to mention in message #23901 that the one recent
    _appropriate_ posting from that subscriber apparently was due
    to a suggestion I made privately.  (I had suggested redirecting
    the obsession with politics toward issues that concern
    cryonicists such as stem cell research.)  That poster thus
    deserves little credit for that one non-spam message.

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