[rdfweb-dev] foaf thoughts

Fri Jul 18 17:00:00 UTC 2003

graham, thanks for these pointers. unfortunately the first host seems to 
be down, i tried again today but no luck there.

josangs stuff i found very interesting as a basis for trust 
calculations. although, as i said, i do not really believe that a 
subjective rating of trust on any scale is a good idea, the subjective 
logic approach might be useful.

f/0

Graham Klyne wrote:
> 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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>> rdfweb-dev at vapours.rdfweb.org
>> wiki: http://rdfweb.org/topic/FoafProject
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> 
> 
> -------------------
> Graham Klyne
> <GK at NineByNine.org>
> PGP: 0FAA 69FF C083 000B A2E9  A131 01B9 1C7A DBCA CB5E
> 
> 

-- 
|-
| Florian Ledermann <ledermann at ims.tuwien.ac.at>
| http://www.ims.tuwien.ac.at/~flo/
|-
| TU Wien - Vienna University of Technology
| Interactive Media Systems Group
| Favoritenstrasse 9-11/188/2
| A-1040 Vienna, Austria
|-
| "I think I'm thinking, therefore I possibly are."
|-