From: iansmith@weasel.cc.gatech.edu (Ian Smith)
Date: Tue, 22 Feb 94 13:04:35 PST
To: cypherpunks@toad.com
Subject: RATINGS: proposal
Message-ID: <9402222102.AA22043@weasel.gatech.edu>
MIME-Version: 1.0
Content-Type: text/plain


Eric: I was about to send this to the cpunx list, but got your message
first. I'll send this to you first, and maybe we can hash out
something better before 'going public' with it... here it is. I had
not thought about the possibility of rating multiple messages in one
"rating message." My scheme doesn't address this, although simple
changes could accomplish it. I'm not sure that I understand why a mail
message could be rated multiple times by the same rator, unless you
mean that one might define "axes of rating", like "content",
"spelling", "novelty", etc.  I think that such a scheme is good, but
is starting to place more load on the rator.  I had hoped that I could
use a slider widget, and have the user generate somewhat reasonable
ratings just by setting the slider to a value between 0 and 100 and
hitting a "rate" button. This would automagically put in motion the
scheme outlined below.

As an MUA implementor, here's my first cut of a proposal for a rating
system that would hopefully meet the goals that eric outlined and be
quickly implementable.

1) Mail to cypherpunks-ratings will be gatewayed back to all members
of the list if it has the following lines in its body [Headers are
ignored...] Lines in brackets are optional:

[whitespace]
Target-Message-Id: <messageId>
Rating: <integer>
[Comment: <newline terminated string>]
[Subtopic: <one word string>]
[Rating-originator: <newline terminated identity string: preferably
PGP public key ident]

[PGP signature]

Body lines which don't have the syntax mentioned above are ignored.

The comment field is intended to allow the person doing the rating to
give info about his rating or the rated message to the rated message
reader, when the message is read. I.e. when I read a message from the
cypherpunk list from joe blow which has been rated by
iansmith@cc.gatech.edu with a comment of "this message is fantastic"
I can get something like:

From: joe blow
Subject: foobar
Rating-Comment: (iansmith@cc.gatech.edu) this message is fantastic! 
Rating: 100

Similarly the subtopic field is to provide an automatic version of
what is now being done by hand with ADMIN: and RATING: in subject
fields or the like.  This would allow a mail user agent to provide
some automatic content help, provided that a displayed mail message
meets enough of its criteria for this (have enough ratings been
received? do 75% of the ratings agree on the subtopic for the mail
message? etc).

The PGP information is intended to facilitate "rating reputations" so
that MUAs could be configured to "trust" ratings from people with good
reputations for rating in ways that meet the user's idea of "goodness."

Now, this strategy doesn't say anything about what the numeric rating
scale means. I favor a 0-100 scale, with 0 being a "don't read this,
its crap" and 100 being "must read." Although ideally this should be a
curve with 50 being very common and 100's and 0's being very uncommon,
it seems unlikely to me that such a system would occur in practice, as
the common case (50) is the MOST unlikely to motivate someone to issue
a rating message.  I'm not sure what to do about this problem.

When the mail messages is echoed out to the ratings mailing list, it
would bear the additional header line: 
X-Mail-Rating: cypherpunks

This would allow the MUA of the recipient to easily recognize the
"ratings mail" messages and not display them to the user.  The MUA
should be building a database or otherwise storing the ratings of mail
messages, so that when it displays a message it can bring up the
appropriate ratings information.  This allows clever user interfaces
to be constructed based on ratings information, especially
reputation-based arragements.  Consider our message from Joe Blow
above and the message display below:

From: joe blow
Subject: foobar

PGP-Signed-Message-Ratings: 7
PGP-Signed-Rating-Average: 67.5
PGP-Signed-Common-Subtopic: DIGICASH
Highest-Rator-Comment: Good discussion of Chaum's methods
Lowest-Rator-Comment:  Stupid rehash of Chaum's approach

Now back the MUA implementation: This database (or other storage)
which I have been discussing is somewhat irritating in its complexity
and storage requirements, but mostly unavoidable because of the
ordering properties of the problem. It is quite likely that one will
receive ratings *before* the mail message itself arrives (in fact,
this may be exactly what you want!) so the MUA will be forced to "sit
on" ratings for messages it hasn't seen yet. 

To make the database/storage problem a bit more managable, MUA's can
delete ratings information when they delete a mail message.  However,
it seems like a good idea to keep this information lying around for
potential searches of an archive of a mailing list. I.e. "Give me
messages which have the rating subtopic of DIGICASH and average
ratings over 50"

Major problems with this scheme:

1) Heavy dependance on Message-Id: field of messages and not all
messages bear one of these. I don't see that is avoidable, since we
must uniquely identify mail messages and the Message-Id is designed to
do this.

2) This scheme rewards people who wait on the mail message ratings to
come in then read the mailing list.  This could be problematic if we
get into a situation where people who should be doing the rating
aren't reading messages (and rating them) because they are waiting on
others to do so.  I'm not really sure how to address this problem;
timeliness cannot be used a factor when considering ratings, because
of the speed differences in different peoples mail transport system
(its unfair to penalize those that have long mail delays or are
vacation).  I think that perhaps some sort of "carrot" should be used
to encourage to rate messages, but I'm not sure what this carrot would
be.


what do ya think?
ian