Re: Call for Editors!

Andy,

On Fri, Mar 21, 2014 at 5:51 AM, Andy Seaborne <andy@apache.org> wrote:

>
>
> PS Were there particular parts of R2RML that took particularly long /
> cause most debate?
>
>
One thing that quickly comes to mind were the issues of tables without PKs;
use of Blank Nodes; what happens if there are NULL values; and the
integration of the Direct Mapping with R2RML.  See this:
http://www.w3.org/TR/r2rml/#default-mappings

I've started to study R2RML, from a formal point of view. R2RML is rather
expressive (I'm using this term loosely). If we map the expressivity of
R2RML to (datalog) rules, there is a total of 57 distinct rules, which
means that there are 57 different ways of generating RDF triples. The
Direct Mapping can be represented in only 3 (datalog) rules.
More info: http://ceur-ws.org/Vol-1035/iswc2013_poster_4.pdf


>
>  Thanks
>>
>> Ivan
>>
>> On 21 Mar 2014, at 24:25 , Juan Sequeda <juanfederico@gmail.com> wrote:
>>
>>  Ivan, all,
>>>
>>> This is our use-case:
>>>
>>> Constitute Project [1] is a search engine for the worlds constitution.
>>> This is a project funded by Google Ideas [2]. We, Capsenta, did the mapping
>>> of the constitution data to RDF and OWL. All of the data was original Excel
>>> spreadsheets (i.e. CSV files). What we did was to import the spreadsheets
>>> into SQL Server, and then used Direct Mapping, R2RML and Ultrawrap to map
>>> the data to RDF. Why did we want to use RDF/OWL? Several reasons:
>>>
>>> 1) RDF (graph data model) is flexible. We don't know what is going to
>>> happen to constitutional data later. So we need to be ready for change
>>> 2) We currently have 189 constitutions, each in it's own spreadsheet. We
>>> need to integrate this data.
>>> 3) We created an ontology about constitutional topics. Naturally, we
>>> want to represent this in OWL.
>>> 4) We want to link to other datasets, such as DBpedia
>>> 5) RDF is becoming the standard to publish open data.
>>>
>>> These reasons are not specific to Constitute. It can apply to any csv
>>> dataset which needs search or integrated with other datasets.  More info
>>> can be found in our 2013 Semantic Web Challenge submission [3]. We won 2nd
>>> prize :)
>>>
>>> Constitute is having a lot of impact. We know for a fact that
>>> constitutional drafters of Tunsia, Egypt and now Mongolia have been using
>>> Constitute.
>>>
>>> Btw, interesting fact: On average, 5 constitutions are written from
>>> scratch every year. A constitution last on average for 20 years. People who
>>> write constitutions have never done that before and will never do that
>>> again; that is why they want to search through existing constitutions.
>>>
>>> [1] https://www.constituteproject.org/#/
>>> [2] https://www.google.com/ideas/projects/constitute/
>>> [3] http://challenge.semanticweb.org/2013/submissions/swc2013_
>>> submission_12.pdf
>>>
>>>
>>> Juan Sequeda
>>> +1-575-SEQ-UEDA
>>> www.juansequeda.com
>>>
>>>
>>> On Thu, Mar 20, 2014 at 12:53 PM, Ivan Herman <ivan@w3.org> wrote:
>>> Sorry if I sound like a broken record, but I would really like to see
>>> and understand the CSV->RDF use cases, also in terms of the people who are
>>> likely to use that. Learning CSV-LD or R2RML-CSV requires a learning curve.
>>> The question is which of the two is steeper for the envisaged user base.
>>>
>>> (I do not have anything against any of the two, but we may have to make
>>> a choice at some point if we go down that route...)
>>>
>>> Ivan
>>>
>>> On 20 Mar 2014, at 18:47 , Gregg Kellogg <gregg@greggkellogg.net> wrote:
>>>
>>>  On Mar 20, 2014, at 10:39 AM, Juan Sequeda <juanfederico@gmail.com>
>>>> wrote:
>>>>
>>>>  If there is going to be a CSV to RDF mapping, shouldn't it be
>>>>> relatively close (if not almost equal to) R2RML. I foresee users doing
>>>>> RDB2RDF mappings with R2RML and having a few (or many) CSV files that they
>>>>> would like to map to RDF too. They would want to continue using the same
>>>>> tool.
>>>>>
>>>>> What we do is import the CSVs to a RDB, and then use R2RML. So as a
>>>>> user who needs to transform to RDF, I would want to have something almost
>>>>> equivalent to R2RML.
>>>>>
>>>>
>>>> This certainly is a valid use case. I was considering what the impact
>>>> on developers using these tools might be. If there is a single tool (and
>>>> spec) which handles the relevant use cases, then it might simplify the life
>>>> of developers. Nothing against R2RML, and if that's the chain a developer's
>>>> working with, the same logic would indicate that having to use something
>>>> like CSV-LD would be a burden.
>>>>
>>>> Gregg
>>>>
>>>>  Juan Sequeda
>>>>> +1-575-SEQ-UEDA
>>>>> www.juansequeda.com
>>>>>
>>>>
>