[rdfweb-dev] foaf thoughts

Thu Jul 17 13:45:01 UTC 2003

You might find this of some interest:
   http://www.itrust.uoc.gr/

Also, there has been some work on modelling of trust using subjective 
logic, where work by Josang seems to be oft-cited; cf.
   http://security.dstc.edu.au/staff/ajosang/

There's also a more application-oriented resource guide here:
   http://www.wiwiss.fu-berlin.de/suhl/bizer/SWTSGuide/

#g
--

At 13:50 17/07/03 +0200, Flo Ledermann wrote:
>hi all, i am new to the FOAF world but already fascinated...
>
>i am carrying this project around in my brain for a long time already, 
>circulating around friendship networks, resource sharing, collaborative 
>filtering and the like, and i already had some prototypes implemented over 
>the years. but now i came across foaf and i think it is really answering a 
>lot of open questions to me...
>
>however, some questions still remain open, and some new emerged, and after 
>i read through the whole archive of rdfweb-dev yesterday, i dare to 
>discuss them with you:
>
>the basic motivation for me is that i think a lot of resources (in the 
>real world) are wasted because of a lack of communication and trust 
>between the individuals - flats are empty, cars are unused or used with 
>only one person sitting in there, mp3 collections are maintained 
>individually, knowledge is not used or has to be acquired from 
>centralized, "official" sources (like google) and so on. as far as real 
>life is concerned, there are established means and procedures to exchange 
>these resources, either in public (via a "market") or in private (via 
>friends that i "trust"), but for the infosphere we lack these established 
>standards.
>
>ok, so far i think i've just written a basic introduction to the foaf 
>ideas :). now for the concrete questions:
>
>- concerning real life resources, these can currently not be expressed in 
>foaf in every details. do i just take any ontology i come across, to 
>describe, for example, that i "own" a "car" that i might "lend" to anyone 
>who i "trust" with a maximum degree of 2 (i.e. a friend or a 
>friend-of-a-friend)? concerning the things itself, i think this is not a 
>problem and even intended like this by rdf and namespaces, but the 
>abstract concepts like "trust", "resource", "lending" etc. should maybe go 
>into the foaf core.
>
>- which leads to the definition of "trust", which has been a topic in this 
>community from the start, as far as i can tell from the archives. i've 
>read jennifer goldbeck's paper, and i don't think that i would want to 
>rate the degree of friendship or trust that i have towards a person on any 
>scale - i think we have to find other ways to enable the user to express 
>and control these things, and to enable the software agents acting on 
>behalf of our users to draw the right conclusions from the rdfweb they are 
>spidering. before i came across foaf, i decided (after many iterations and 
>discussions of the topic) that i would want to have two basic relationship 
>types, "knows" and "trusts", without any further specification or 
>quantification (of course that can always be layered on top of that). i 
>think with these two relationships we could go a long way, because i would 
>have some way for rapidly extending my personal network with people i 
>know, without giving away too much control and still connecting to my 
>friends (the people i trust) in a tighter way.
>
>- for querying and using the network, this would give quite powerful 
>capabilities. things like "ask all people i know and who live in my town 
>whether they have a welding machine" or "allow all people i trust to a 
>degree of two or less to download mp3s from me" are then possible. but how 
>do i formulate these queries (for now, on a technical level rather than a 
>ui level)? is there any rdf query language that can perform these kind of 
>tasks?
>
>- now comes a hard one: in the real world, i give out different 
>information depending on who is talking to me. a friend knows a lot about 
>me (including address, resources, but also personal details, interests 
>etc.), whereas towards a strangr i might be more careful with giving out 
>information or i might even lie to him/her! how do we model that in 
>rdf/foaf? i know this has been discussed on the list, but for me no 
>conceptual solution was ever presented. i don't like the cryptographic 
>approaches that have been discussed, because they might ensure integrity 
>of the information, but i am more interested in this on a conceptual level 
>- how do we want this to work? i think the cryptographic approaches are 
>just not fine-grained enough to solve this.
>
>first of all, we have to find some way of describing these constraints in 
>foaf - which parts of my foaf file are given out to whom. to do that, one 
>would need a kind of pattern language, and persons/agents matching the 
>patterns (similar to a query, but a kind of ex-post query) would receive 
>the information. on an implementation level, we would have to move away 
>from openly published foaf files, and put them behind a kind of "firewall" 
>(which i would maybe call "skin") to protect the personal information and 
>only give out the information that i want the other agent to receive. this 
>would require some kind of authentication/identification mechanism ("i am 
>an agent asking in behalf of this person for that information"), but could 
>still be realized in http.
>
>the major implication of such a feature would be that it requires more 
>infrastructure to set it up - at least a webserver that you can control 
>and script to a certain amount - and would therefore go away a bit from 
>the grassroots p2p approach that is possible now. on the other hand - it 
>is just an optional enhancement, and people could still publish thier 
>public info through static rdf files, as they do now.
>
>of course one would then use cryptographic approaches to ensure the 
>integrity of authentifications and so on, but i am not interested in 
>cryptography and could personally live with potential misuse, in a 
>prototype phase. but i am sure there are people out there who can solve 
>these problems.
>
>
>- finally, a few usecases i am interested in, and i would be happy to 
>contribute to foaf and the surrounding tools to be able to realize them:
>
>+ collaborative filtering/forwarding of messages through my foaf network
>+ mp3/movie recommendations (and maybe sharing, but that would require 
>additional software installed at the users machine, which at this point 
>probably goes too far.)
>+ car sharing and "who can give me a ride" service
>+ resource sharing (tools, space, knowledge)
>
>ah, btw you can have a look at a system i started to develop (a kind of 
>proprietary foaf) at http://architekt.ims.tuwien.ac.at/map/map.php - it's 
>defunct at the moment (transitioning to foaf ;), but you can take it as a 
>proof for my commitment/skills if you want :) ah, and the "new entity" 
>dhtml form might be handy for the foaf-o-matic, i am especially proud of 
>the expandable "connections" list. not sure if this works outside mozilla 
>though.
>
>phew, pretty long mail, nevertheless hoping for feedback...
>
>all the best,
>
>f/0
>
>http://www.mediavirus.org/f/0/foaf.rdf
>
>--
>|-
>| Florian Ledermann <ledermann at ims.tuwien.ac.at>
>| http://www.mediavirus.org/f/0/
>|-
>| "I think I'm thinking, therefore I possibly are."
>|-
>
>
>
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-------------------
Graham Klyne
<GK at NineByNine.org>
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