Hello Denny,
I was traveling for the past few weeks and can finally answer your email.
See my comments inline.

On 05/29/2012 05:25 PM, Denny Vrandečić wrote: 
Hello Sebastian,


Just a few questions - as you note, it is easier if we all use the same
standards, and so I want to ask about the relation to other related
standards:
* I understand that you dismiss IETF RFC 5147 because it is not stable
enough, right?
The offset scheme of NIF is built on this RFC.
So the following would hold:
@prefix ld: <http://www.w3.org/DesignIssues/LinkedData.html#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
ld:offset_717_729  owl:sameAs ld:char=717,12 .


We might change the syntax and reuse the RFC syntax, but it has several issues:
1.  The optional part is not easy to handle, because you would need to add owl:sameAs statements:

ld:char=717,12;length=12,UTF-8 owl:sameAs ld:char=717,12;length=12 .
ld:char=717,12;length=12,UTF-8 owl:sameAs ld:char=717,12 .
ld:char=717,12;UTF-8 owl:sameAs ld:char=717,12;length=9876 .

So theoretically ok, but annoying to implement and check.

2. When implementing web services, NIF allows the client to choose the prefix:
http://nlp2rdf.lod2.eu/demo/NIFStemmer?input-type=text&nif=true&prefix=http%3A%2F%2Fthis.is%2Fa%2Fslash%2Fprefix%2F&urirecipe=offset&input=President+Obama+is+president.
returning URIs like <http://this.is/a/slash/prefix/offset_10_15>
So RFC 5147 would look like:
<http://this.is/a/slash/prefix/char=717,12>
<http://this.is/a/slash/prefix/char=717,12;UTF-8>
or
<http://this.is/a/slash/prefix?char=717,12>
<http://this.is/a/slash/prefix?char=717,12;UTF-8>

3. Character like = , prevent the use of prefixes:
echo "@prefix ld: <http://www.w3.org/DesignIssues/LinkedData.html#> .                                      
@prefix owl: <http://www.w3.org/2002/07/owl#> .
ld:offset_717_729  owl:sameAs ld:char=717,12 .
" > test.ttl ; rapper -i turtle  test.ttl

4. implementation is a little bit more difficult, given that :
$arr = split("_", "offset_717_729") ;
switch ($arr[0]){
    case 'offset' :
        $begin = $arr[1];
        $end = $arr[2];
        break;
    case 'hash' :
        $clength = $arr[1];
        $slength = $arr[2];
        $hash = $arr[3];
        $rest = /*merge remaining with '_' */
        break;
}

5. RFC assumes a certain mime type, i.e. plain text. NIF does have a broader assumption. 
* what is the relation to the W3C media fragment URIs? Did not find a
pointer there.
They are designed for media such as images, video, not strings.  Potentially, the same principle can be applied, but it is not yet engineered/researched. 
* any plans of standardizing your approach?
We will do NIF 2.0  as a community standard and finish it in a couple of months. It will be published under open licences, so anybody W3C or ISO might pick it up, easily. Other than that there are plans by several EU projects (see e.g. here http://lists.w3.org/Archives/Public/public-multilingualweb-lt/2012Jun/0101.html) and a US project to use it and there are several third party implementations, already.  We would rather have it adopted first on a large scale and then standardized, properly, i.e. W3C. This worked quite well for the FOAF project or for RDB2RDF Mappers.
Chances for fast standardization are not so unlikely, I would assume. 
We would strongly prefer to just use a standard instead of advocating
contenders for one -- if one exists.
You might want to look at: http://www.w3.org/community/openannotation/wiki/TextCommentOnWebPage
and the same highlighting here:
http://pcai042.informatik.uni-leipzig.de/~swp12-9/vorprojekt/index.php?annotation_request=http%3A%2F%2Fwww.w3.org%2FDesignIssues%2FLinkedData.html%23hash_10_12_60f02d3b96c55e137e13494cf9a02d06_Semantic%2520Web

NIF equivalent (4 triples instad of 14 and only one generated uuid):
ld:hash_10_12_60f02d3b96c55e137e13494cf9a02d06_Semantic%20Web a str:String ;
    oa:hasBody [
        oa:annotator <mailto:Bob> ;
        cnt:chars "Hey Tim, good idea that Semantic Web!" .
    ]

So you might not think in a "contender" way. Approaches are complementary. NIF is simpler and the URIs have some features that might be wanted (stability, uniqueness, easy to implement).
This is why I was asking for your *use case* .

Note that: there are still some problems, when annotating DOM with URIs, e.g. xPointer is abandoned and was never finished. Xpath has its limits and is also expensive (i.e. SAX not possible).
I think there is no proper solution as of now.
All the best,
Sebastian


Cheers,
Denny




2012/5/18 Sebastian Hellmann <hellmann@informatik.uni-leipzig.de>


Hello again,
maybe the question, I asked was lost, as the text was TL;DR

I heard that, it is planned to track provenance of facts. e.g. Berlin has
3,337,000 citizens found here: http://www.worldatlas.com/**citypops.htm<http://www.worldatlas.com/citypops.htm>
Do you have a place where the use case and the requirements are documented
for this? Or is it out of scope?
Will it be course grained, i.e. website level ? Or fine grained, i.e. text
paragraph level? See e.g. how Berlin is highlighted here:
http://pcai042.informatik.uni-**leipzig.de/~swp12-9/**
vorprojekt/index.php?**annotation_request=http%3A%2F%**
2Fwww.worldatlas.com%**2Fcitypops.htm%23hash_4_30_**
7449e732716c8e68842289bf2e6667**d5_Berlin%2C%2520Germany%2520-**%25203%2C<http://pcai042.informatik.uni-leipzig.de/~swp12-9/vorprojekt/index.php?annotation_request=http%3A%2F%2Fwww.worldatlas.com%2Fcitypops.htm%23hash_4_30_7449e732716c8e68842289bf2e6667d5_Berlin%2C%2520Germany%2520-%25203%2C>
in this very early prototype.

Could you give me a link were I can read more about any Wikidata plans
towards this direction?
Sebastian



On 05/16/2012 09:10 AM, Sebastian Hellmann wrote:


Dear all,
(Note: I could not find the document, where your requirements regarding
the tracking of facts on the web are written, so I am giving a general
introduction to NIF. Please send me a link to the document that specifies
your need for tracing facts on the web, thanks)

I would like to point your attention to the URIs used in the NLP
Interchange Format (NIF).
NIF-URIs are quite easy to use, understand and implement. NIF has a
one-triple-per-annotation paradigm.  The latest documentation can be found
here:
http://svn.aksw.org/papers/**2012/WWW_NIF/public/string_**ontology.pdf<http://svn.aksw.org/papers/2012/WWW_NIF/public/string_ontology.pdf>

The basic idea is to use URIs with hash fragment ids to annotate or mark
pages on the web:
An example is the first occurrence of "Semantic Web" on
http://www.w3.org/**DesignIssues/LinkedData.html<http://www.w3.org/DesignIssues/LinkedData.html> as highlighted here:
http://pcai042.informatik.uni-**leipzig.de/~swp12-9/**
vorprojekt/index.php?**annotation_request=http%3A%2F%**
2Fwww.w3.org%2FDesignIssues%**2FLinkedData.html%23hash_10_**12_**
60f02d3b96c55e137e13494cf9a02d**06_Semantic%2520Web<http://pcai042.informatik.uni-leipzig.de/~swp12-9/vorprojekt/index.php?annotation_request=http%3A%2F%2Fwww.w3.org%2FDesignIssues%2FLinkedData.html%23hash_10_12_60f02d3b96c55e137e13494cf9a02d06_Semantic%2520Web>

Here is a NIF example for linking a part of the document to the DBpedia
entry of the Semantic Web:
<http://www.w3.org/**DesignIssues/LinkedData.html#**offset_717_729<http://www.w3.org/DesignIssues/LinkedData.html#offset_717_729>

     a str:StringInContext ;
     sso:oen <http://dbpedia.org/resource/**Semantic_Web<http://dbpedia.org/resource/Semantic_Web>>
.


We are currently preparing a new draft for the spec 2.0. The old one can
be found here:
http://nlp2rdf.org/nif-1-0/

There are several EU projects that intend to use NIF. Furthermore, it is
easier for everybody, if we standardize a Web annotation format together.
Please give feedback of your use cases.
All the best,
Sebastian



--
Dipl. Inf. Sebastian Hellmann
Department of Computer Science, University of Leipzig
Projects: http://nlp2rdf.org , http://dbpedia.org
Homepage: http://bis.informatik.uni-**leipzig.de/SebastianHellmann<http://bis.informatik.uni-leipzig.de/SebastianHellmann>
Research Group: http://aksw.org


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-- 
Dipl. Inf. Sebastian Hellmann
Department of Computer Science, University of Leipzig
Projects: http://nlp2rdf.org , http://dbpedia.org
Homepage: http://bis.informatik.uni-leipzig.de/SebastianHellmann
Research Group: http://aksw.org