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Re: Formal Objection to RDF Working Group resolution of issue 165

From: Michael Schneider <schneid@fzi.de>
Date: Wed, 26 Feb 2014 23:17:07 +0100
Message-ID: <530E67E3.6050405@fzi.de>
To: Ivan Herman <ivan@w3.org>
CC: "public-rdf-comments@w3.org Comments" <public-rdf-comments@w3.org>, "W3C Chairs of RDF WG" <team-rdf-chairs@w3.org>, Tim Berners-Lee <timbl@w3.org>
Ivan, all,

I would like to thank you for having discussed my formal objection.

Best regards,
Michael

Am 25.02.2014 16:26, schrieb Ivan Herman:
> Dear Michael,
>
> As you may have seen, the RDF 1.1 Recommendations have just been published. The official mail sent to the AC representatives also includes a reaction to this mail as follows:
>
> [[[
> As reported in the Call for Review, Michael Schneider raised an objection
> that was not upheld by the Director. The objection was reiterated in a
> public email [2]. The Director has discussed the objection with the
> Working Group Chairs and the Team Contact, and supports their
> determination that the Working Group has considered the issue fully.
> ]]]
>
> Ivan
>
>
>
>
>
> On 09 Feb 2014, at 23:49 , Michael Schneider <schneid@fzi.de> wrote:
>
>> To the director of the W3C,
>> to the chairs and W3C team members of the RDF Working Group,
>> to the members of the RDF Working Group,
>> and to anyone else to whom it may concern.
>>
>> This is a formal objection to a change made to the semantics of
>> datatypes in the Proposed Recommendation of the RDF 1.1 Semantics.
>> The change concerns the replacement of the original concept of
>> a "datatype map" by the concept of a "set of recognized datatype
>> IRIs". I will argue that this change is largely unmotivated and
>> unnessesary, technically incompatible with the original concept,
>> questionable and even flawed, and may lead to diverse problems
>> for dependent Semantic Web standards and other dependent work.
>> My proposal will be to revert the change to the original
>> definition as of 2004 and to postpone further discussion of
>> the change to a future RDF Working Group. This formal objection
>> follows my reviews of earlier versions of the RDF 1.1 Semantics
>> and my discussions with the RDF Working Group about the same
>> topic, which did not lead to a satisfiable conclusion for me.
>>
>> Michael Schneider,
>> Frankfurt am Main (Germany), 9 Febrary 2014
>>
>>
>> == Introduction ==
>>
>> This is a formal objection to a change made by the RDF Working
>> Group to the semantics of datatypes in the RDF 1.1 Semantics
>> compared to the original RDF Semantics specification as
>> of 2004 (from now on called "RDF 2004") [01]. The formal
>> objection targets the Proposed Recommendation (PR) of the
>> RDF 1.1 Semantics [02], which still underwent some changes
>> compared to the previous versions of the document, and which
>> is now intended by the Working Group to become the final
>> recommendation. The formal objection follows my reviews
>> of earlier versions of the RDF 1.1 Semantics and my
>> discussions with the RDF Working Group about the same
>> topic [03][04], which did not lead to a satisfiable
>> conclusion for me [05]. I have to point out that this formal
>> objection is not made by an official W3C member organisation,
>> and none of the organisations I am affiliated with
>> or in some current relationship with has is involved.
>> Rather, the formal objection is made by me as a private person,
>> and as a member of the informal Semantic Web community,
>> who has considerably contributed to the Semantic Web initiative
>> in the past and has a strong background and a stake
>> particularly in the RDF Semantics; see the section
>> "About the Author" for information about me.
>>
>> The change to which I formally object concerns the replacement
>> of the original concept of a "datatype map" in Chap. 5 of [01]
>> by the concept of a "set of recognized datatype IRIs"
>> in Chap. 7 of [02]. In the original RDF 2004 Semantics,
>> a datatype map has been a set of associations between datatype
>> IRIs (originally URI references) and datatypes. In the RDF 1.1
>> Semantics PR, there is now a "set of recognized datatype IRIs",
>> that is, only the datatype IRIs, together with the additional
>> requirement of the existence of a globally unique mapping
>> between datatype IRIs and datatypes (where this unique mapping
>> is not intended to be fully defined by the RDF 1.1 spec).
>> I will describe the chnge in more detail in Section
>> "Description of the Change".
>>
>> I will first argue, in Section "A Non-Editorial Change", that the
>> change is not simply an editorial change, and will give arguments,
>> in Section "Missing Motivation and Necessity for the Change", why
>> I consider the change unmotivated and unnecessary. In Section
>> "Technical Consequences of the Change", I will list what I
>> consider the most relevant technical consequences of the change,
>> and will also give examples for possible practical consequences.
>> I will then, in Section "Consequences for dependent Semantic Web
>> Standards and other Work", argue that the change may have
>> unfortunate consequences for other existing Semantic Web Standards,
>> which are based on RDF, such as OWL 2, SPARQL 1.1, and RIF,
>> and may possibly lead to a split situation, where some of future
>> versions of these standards will adopt the change made in RDF
>> while others may not.
>>
>> Finally, in Section "Conclusions and Proposal", I will summarize
>> my arguments and argue that the consequences to be expected from
>> the change are strong and undesiarable, and would not exist if
>> the original notion of datatype maps would have been retained.
>> Consequencly, I will propose to revert the change to the original
>> situation as of RDF 2004, and to postpone further discussion of
>> the change to a future RDF Working Group.
>>
>>
>> == Description of the Change ==
>>
>> RDF 2004 introduced the concept of a "datatype map", "being a set
>> of pairs of a IRI and a datatype such that no IRI appears twice
>> in D" (Chap. 5 of [01]; note: in order to ease the discussion,
>> I use the term "IRI" everywhere, although the RDF 2004 spec used
>> the term "URI reference" instead.) In the current PR of the
>> RDF 1.1 Semantics, D is not a set of IRI-datatype pairs anymore,
>> but a set of datatype IRIs only (Chap. 7 of [02]). It is also
>> not called a "datatype map" anymore, but is now called a
>> "set of recognized datatype IRIs".
>>
>> The RDF 1.1 Semantics further states that (a) "the semantics
>> presumes that a recognized IRI identifies a unique datatype
>> wherever it occurs", and (b) that "the exact mechanism by
>> which an IRI identifies a datatype is considered to be
>> external to the semantics" (beginning of Chap 7).
>> The second Change Note in Chap. 7 informally elaborates
>> on this statement by saying that "the current semantics
>> presumes that a recognized IRI identifies a unique datatype,
>> this IRI-to-datatype mapping is globally unique and externally
>> specified". In contrast, RDF 2004 did not require a globally
>> unique association between datatype IRIs and datatypes.
>> Rather, the definition of datatype maps made it possible to
>> have IRI-datatype associations being unique only locally with
>> regard to a particular datatype map D, or, likewise, locally
>> unique to an entailment regime that uses a particular datatype
>> map D.
>>
>> To illustrate the difference, consider the case of a custom
>> definition of D-RDFS with D including a new custom datatype.
>> In RDF 2004, it was possible to associate the the same IRI
>> to one datatype in one datatype map D1 and to a different
>> datatype in another datatype map D2. For example, the IRI
>> "ex:complex" may have been associated to a datatype
>> representing the mathematical field of complex numbers
>> in one extension of RDFS, and to a datatype representing
>> four-dimensional composites of real numbers for the
>> representation of space-time events in another extension
>> of RDFS. Under the RDF 1.1 Semantics, which requires the
>> existence of a globally unique IRI-datatype association,
>> this will not be possible anymore (regardless what the
>> globally unique IRI-datatype association will look like,
>> which is, as cited above, not fully determined by the
>> RDF 1.1 standard).
>>
>> In addition, some of the semantic conditions related to
>> the semantics of datatype have been adjusted in order to
>> reflect the change mentioned above on a technical level.
>> In general, the semantic conditions now refer to applications
>> of a given interpretation I to a datatype IRI aaa, "I(aaa)",
>> instead of referring to the associated datatype by its
>> reference given in the datatype map, as was done in RDF 2004.
>> For example, compare the second of the Semantic conditions
>> for datatype literals in Chap. 7 of [02] with the third of
>> the General semantic conditions for datatypes in Chap. 5
>> of [01].
>>
>> To summarize, the whole change here includes:
>>
>>   * a change in nomenclature:
>>     ("datatype map" vs. "set of recognized datatype IRIs");
>>
>>   * a change in the formal representation of the objects
>>     under consideration: a set of IRI-datatype pairs vs.
>>     a set of IRIs only plus an additional globally unique
>>     IRI-datatype association, together with adjustments
>>     to the semantic conditions for datatype semantics;
>>
>>   * a change to the scope of uniqueness of IRI-datatype
>>     associations: this scope has been local to every
>>     particular datatype map in RDF 2004 while being global,
>>     and by intention mostly undetermined, in RDF 1.1.
>>
>>
>> == A Non-Editorial Change ==
>>
>> It has been argued by the Working Group that the change is of
>> a purely editorial nature. I would certainly not formally
>> object to an editorial change, but consider this a non-editorial
>> change. An editorial change would not change basic nomenclature
>> or formal or technical aspects of a specification, and all this
>> is the case here.
>>
>> Firstly, as stated above, the change introduced a change in
>> nomenclature from the notion of a "datatype map" to the notion
>> of a "set of recognized IRIs". Secondly, there have been some
>> changes to the underlying formal representation, as listed above.
>> Thirdly, and most notably in my opinion, the change of scope of
>> uniqueness of IRI-datatype associations has changed. This change
>> does have measurable effects, as I have already pointed out
>> by my example above where the same IRI "ex:complex" is used
>> for different datatypes: this is clearly possible in RDF 2004,
>> but will not be possible anymore in RDF 1.1.
>>
>> Another way of looking at the question whether a change to a
>> specification is editorial or not is to check whether existing
>> dependent work, such as other specifications, scientific papers,
>> or text books, would need to be updated in non-trivial ways
>> in order to be in line again with the changed specification.
>> For the change here, it becomes clear that dependent work
>> needs to be updated concerning the same things that have
>> changed in the RDF specification. For example, a text book
>> that is of a more formal nature would probably need to change
>> its used nomenclature from "datatype maps" to "sets of
>> recognized IRIs", its basic definitions from sets of pairs
>> IRI-datatype pairs to sets of IRIs, and would need to reflect
>> the change in the scope of uniqueness of the IRI-datatype
>> associations.
>>
>> Based on these arguments, I conclude that the change is
>> clearly non-editorial.
>>
>>
>> == Missing Motivation and Necessity for the Change ==
>>
>> A non-editorial change in a specification requires good
>> motivation, and this is particularly true in the case of
>> RDF and its semantics, for which the charta of the
>> RDF 1.1 Working Group [06] explicitly requires that
>> "changing the fundamentals of the RDF Semantics" are
>> out of scope for the WG (Chapter 3). Based on my arguments
>> given below in the text concerning technical consequences
>> of the change, I consider the change to be indeed a change
>> of the fundamentals of the RDF semantics, and thus in
>> conflict with the charta.
>>
>> In general, the scope of the RDF WG was held deliberately
>> conservative. According to its charta, the scope was
>> "to extend RDF to include some of the features that the
>> community has identified as both desirable and important
>> for interoperability based on experience with the 2004
>> version of the standard, but without having a negative
>> effect on existing deployment efforts." However, I am not
>> aware of any input from outside the working group during
>> the past 10 years since RDF 2004 became a recommendation
>> that would have asked for a change of the semantics
>> concerning the concept of datatype maps, or would have
>> indicated any problems with this concept. Rather, within
>> the previous years, at least three other core Semantic Web
>> standards have been written (OWL 2, SPARQL 1.1, and RIF),
>> which reuse the original notion of datatype maps without
>> any known problems, each taking years of specification
>> work and building up considerable experience with these
>> things. I am also not aware of any discussion concerning
>> problems with datatype maps from either the workshop or
>> the questionnaire that had preceeded the initiation of
>> the Working Group.
>>
>> As far as I am concerned myself, I have been responsible
>> for editing one of the mentioned dependent standards
>> (the OWL 2 RDF-Based Semantics), which makes heavy use of
>> the original definitions for datatype and datatype maps.
>> I have also provided some technical support (both in
>> private and public conversation) to the editors of
>> SPARQL 1.1 Entailment Regimes and RIF RDF&OWL Compatibility
>> with regard to the RDF semantics in general and to datatype
>> related semantics in particular. I have further created
>> several large test suites, which are to a large extent
>> about datatype semantics. I have created many formal proofs
>> based on the datatype semantics of RDF. I have spend some
>> time thinking about the implementation of datatype semantics,
>> although not yet implemented into my RDF Semantics reasoner
>> called Swertia. And overall I have been working in the
>> RDF field fulltime continuously for the last 8 years up to
>> the day. But in all these years with all this gained
>> experience concerning the RDF Semantics in general and
>> RDF datatype semantics in particular, I have never
>> encountered any serious problems with the original notion
>> of datatype maps. Rather, I have always found the original
>> datatype semantics well designed and it allowed me to do my
>> work decently. I would never have come to the conclusion that
>> anything would require a change, in particular not a change
>> of the kind proposed in RDF 1.1.
>>
>> In fact, from my earlier discussion with the Working Group
>> it became apparent to me that the change was not based on
>> input from the outside, as was requested by the charta,
>> but only from within the Working Group. In the context of the
>> charta, this would have only be acceptable, if there was a
>> strong reason, such as a so far unnoticed bug. The actual
>> rational of the Working Group was then to simplify the current
>> presentation of the RDF semantics [07]. Having given my arguments
>> above about the complete lack of request for a change and the
>> much work that has been carried out without problems based on
>> the original definitions, it should be clear that I do not see
>> any reason here for any form of simplification with regard
>> to the original situation. But of even more relevance is
>> that the changes have not really "simplified" the situation,
>> but have rather changed the situation and introduced
>> significant technical problems, as I will point out in
>> the following section.
>>
>>
>> == Technical Consequences of the Change ==
>>
>> Probably the most notable technical aspect of the change
>> is that it is now assumed by the RDF 1.1 Semantics that there
>> exists a globally unique IRI-datatype association, which is
>> to be applied for each set D of recognized IRIs (as an
>> integral part of an interpretation I). In comparison, no
>> such unique IRI-datatype association was assumed in RDF 2004,
>> but the concept of datatype maps allowed to have different
>> datatype maps sharing the same IRI but associated with
>> different datatypes. Further, the RDF 1.1 Semantics PR
>> does not define this globally unique IRI-datatype association,
>> but considers its definition to be external to the semantics,
>> except for a small number of datatype IRIs from the XSD
>> namespace. This difference has a number of considerable
>> technical consequences.
>>
>> The first technical problem is that the change strongly reduces
>> the number of possible constellations of IRI-datatype associations:
>> In RDF 2004, for any set of IRIs i1,...,in there were, in principle,
>> infinitely many possible datatype maps D = { (i1,d1), ..., (in,dn) }.
>> In RDF 1.1, however, the associated datatypes d1,...,dn are uniquely
>> determined to be those from the globally unique IRI-datatype
>> association, which means that there is only a single such IRI-datatype
>> association for the given set of IRIs.
>>
>> An example for a possible practical consequence, which I have
>> already mentioned earlier, is that of two entailment regimes
>> sharing the same datatype IRI "ex:complex", but associated to
>> different datatypes, namely the mathematical field of complex
>> numbers on one hand, and a set of compounds of four real numbers
>> to represent space-time events. In general, it should be expected
>> that in certain fields custom datatypes will be developed and
>> used, without the need to wait for an international standardisation
>> of a IRI. The problem here is that if such a situation of concurrent
>> IRI-datatype associations occurs, at least one of the entailment
>> regimes will not be compliant with the RDF 1.1 standard anymore,
>> due to the fact that the RDF 1.1 standard demands that there is
>> a globally unique datatype associated for any given datatype IRI.
>> While this will hardly stop organisations from still developing
>> and using their custom datatypes, the situation is annoying and
>> undesirable, and it could trivially be avoided by sticking with
>> the original concept of datatype maps from RDF 2004.
>>
>> The second technical problem is that, as the RDF 1.1 Semantics PR
>> does neither provide nor ask for an explicit set of the globally
>> unique IRI-datatype association, the task of proving certain
>> semantic properties, such as the soundness and completeness
>> of reasoning algorithms or reasoning tools, may become problematic
>> or even impossible. For example, if we have some reasoner R that
>> accepts pairs of RDF graphs and outputs boolean values,
>> and we ask whether R is sound and complete with regard to D-RDFS,
>> for D including the datatype IRI "ex:complex", how can we proof
>> or disproof whether this semantic property holds for R or not?
>> As mentioned earlier, there may be more than one obvious datatypes
>> associated with "ex:complex", and unless we know the "right" one,
>> we simply cannot start proof work.
>>
>> This has not been a problem in RDF 2004, where the proof work
>> would have been done with regard to D-RDFS having an explicitly
>> defined datatype map D, which would have included a reference to
>> the datatype associated with "ex:complex". In fact, it would have
>> been possible to have D1-RDFS and D2-RDFS, both including the
>> IRI "ex:complex" but with different associated datatypes. R would
>> then, perhaps, have been sound and complete w.r.t. D1-RDFS but not
>> w.r.t. D2-RDFS, but, in any case, the proof work would have been
>> possible technically and its result would be been perfectly
>> determined.
>>
>> The third technical problem is that the assumption of the existence
>> of a globally unique, but completely open to an externally provided
>> definition, set of IRI-datatype association breaks, strictly
>> speeking, or at leasts "confuses" the RDF Semantics. As there are
>> no further limitations on the set of IRIs for which there can
>> be associated datatypes, there may be a datatype for
>> /every possible/ IRI, including every IRI defined for other
>> purposes by the RDF Semantics itself or elsewhere in the
>> Semantic Web. Hence, for any given D interpretation I and
>> any given IRI aaa, there exists some datatype d such that
>> I(aaa) = d. This horrible semantic concequence was certainly
>> not intended by the Working Group, but it is a consequence of
>> missing restrictions on the set of IRIs allowed to act as
>> datatype IRIs. However, I cannot imagine any meaningful constraint
>> on the names of datatype IRIs, so this problem will hardly be
>> eliminated by adding whatever constraint. Again, this problem
>> has not existed in RDF 2004, since there has not been such an
>> assumption about a globally unique but indetermined IRI-datatype
>> association.
>>
>>
>> == Consequences for dependent Semantic Web Standards and other Work ==
>>
>> For existing Semantic Web standards that depend on the
>> RDF semantics and specifically on the original notion
>> of datatype maps, the change will mean that these standards
>> are not fully aligned anymore with the new version of RDF.
>> The most important standards that are directly affected
>> in this way are:
>>
>>   * OWL 2, specifically the OWL 2 RDF-Based Semantics,
>>     which is a conservative semantic extension of
>>     RDF 2004 D-entailment and makes strong use of the
>>     original datatype semantics;
>>
>>   * SPARQL 1.1, specifically the RDF 1.1 Entailment Regimes,
>>     which defines query results for querying on top of the
>>     different RDF 2004 entailment regimes, including D entailment
>>     and the also affected OWL 2 RDF-Based Semantics;
>>
>>   * RIF, specifically the RIF RDF and OWL Compatibility spec,
>>     which defines RIF-X combinations, for X being any of the
>>     entailment regimes defined by the RDF 2004 Semantics
>>     and also the affected OWL 2 RDF-Based Semantics.
>>
>> Notwithstanding the question whether the change leads to relevant
>> technical consequences, there will at least be a mismatch in
>> nomenclature, concepts, and formal representation. In fact, all
>> listed standards above explicitly refer to the definition of
>> datatype maps and use them for their own purpose.
>>
>> For example, the OWL 2 RDF-Based Semantics, following the
>> definitions of OWL 2 in general, introduces a specific
>> minimal datatype map consisting of a required set of
>> IRI-datatype associations, which even include several new
>> datatypes that have been introduced for specifically for
>> OWL 2 (and in part for RIF). The OWL 2 RDF-Based Semantics
>> considers any reasoner that fully supports /at least/
>> these IRI-datatype associations as a compliant
>> OWL 2 RDF-Based reasoner, and allows such a reasoner
>> to support /arbitrary/ additional IRI-datatype associations;
>> which is, strictly speaking, in conflict with the idea
>> of a globally unique set of IRI-datatype associations.
>>
>> In general, I do not consider the change here to be of a sort
>> that would easily and naturally be implemented in future versions
>> of these dependent standards. It is by far not an obvious change,
>> or even only a "simplification" of the original situation.
>> Rather, it affects several aspects such as basic nomenclature,
>> formal representation, and even semantic assumptions about the
>> form of the interpretation functions. I am even unsure whether
>> all future working groups for these dependent standards will
>> be willing to adopt the change made to RDF 1.1, as this would
>> probably bring little value for these other standard beyond
>> formal compliance with RDF 1.1, but to the expense of possibly
>> breaking backwards compatiblity with the original version of
>> this other standard, as in the case of the OWL 2 RDF-Based
>> Semantics. So we may eventually find ourselves in a situation,
>> where some of the Semantic Web standards will follow the change
>> taken in RDF, while other's won't. This would, of course,
>> be a highly unfortunate and embarrassing situation, in
>> particular as the situation would be perfectly easily avoided
>> by simply avoiding the applied change to RDF in the first place.
>>
>> Similar consequences as for dependent standards are to be expected
>> for other existing work depending on or building on top of RDF,
>> such as text books on RDF or other semantic technologies,
>> university courses, research papers, software, etc.
>>
>>
>> == Conclusions and Proposal ==
>>
>> I have argued that the current change is a non-editorial change
>> that leads to certain incompatibilities with RDF 2004
>> and generally to undesirable consequences, such as
>> that it restricts the flexibility of defining custom entailment
>> regimes, a potential lack of well-definedness in questions
>> such as about soundness and completeness for reasoning algorithms
>> and tools, and even a technically flawed semantics by implicitly
>> requiring any existing IRI to be interpreted as some datatype.
>> This may have practical consequences for the application of
>> the RDF standard, and may lead to issues for existing other
>> Semantic Web standards, up to the danger of breaking compatibility
>> with earlier versions of these standards, if adopted,
>> or alternatively to a split situation, where some future versions
>> of these standards will not adopt the change made to RDF.
>>
>> I have further noted that none of these problems existed
>> for the original definition of datatype maps, and that no
>> other technical problems of datatype maps have been
>> brought up ever since from the outside to the RDF WG,
>> as originally required by the WG charta, although the
>> RDF specification, and particularly the notion of datatype
>> maps, has been in heavy use for a decade. In fact, the
>> rational for the change was essentially to only simplify
>> the original situation without any technical change.
>> As I have argued, the change /is/ technical, and has
>> considerable problematic consequences, while there was no
>> known request in the past even for simplification - a
>> point that I can well confirm as someone who has worked
>> a lot with the definition of datatype maps in the past,
>> including specification work, the creation of test suites,
>> and formal proof work.
>>
>> I therefore propose to fully revert the change to the original
>> notion of datatype maps to the form as it appears in the
>> original RDF specification as of 2004. This will be a valid
>> operation since, as I have argued, there was nothing really
>> wrong with the original definitions. It will also be a
>> preferable operation, since existing Semantic Web standards
>> and other published documents will continue to be compatible
>> with RDF 1.1, and their future authors will not be forced
>> into a decision whether to follow the change in the RDF semantics,
>> or to stick with the old definitions, where either choice may
>> be leading to certain compatibility issues.
>>
>> I expect that such a revert will be technically and editorially
>> easy, as the change is, fortunately, not very strongly entangled
>> with other parts of the specification, and the changes to the
>> semantics of datatypes are pretty straightforward.
>>
>> However, I do not suggest to completely abondon the idea of the
>> change. As there has been much discussion on the topic within
>> the Working Group but essentially none outside of it, neither
>> before the WG has started nor during its active time, I consider
>> it purposeful to put the change to the list of postponed issues
>> to be treated by a future RDF working group. By this, the proposed
>> change gets the chance to become known and discussed outside the
>> Working Group, and in particular by future working groups of
>> other standards that are based on the RDF Semantics. I believe
>> that, given the lack of request from outside the Working Group,
>> there is certainly no urge of applying this change to RDF now.
>>
>>
>> == About the Author ==
>>
>> I have been the editor of the W3C OWL 2 RDF-Based Semantics
>> specification, and have been a contributor for several of
>> the other core OWL 2 specification documents, including the
>> OWL 2 Mapping to RDF and the OWL 2 RL/RDF Rules profile.
>> I have contributed part of the W3C OWL 2 test suite with
>> a focus on RDF-based reasoning, and have also created a
>> much larger version of this and several other test suites
>> concerning RDF semantics-based reasoning (some of them yet
>> to be published). I have provided, in both private and public
>> conversation, support to the editors of the SPARQL 1.1
>> Entailment Regimes and the RIF RDF and OWL Compatibility
>> specification on topics concerned with the RDF Semantics.
>> I have worked in several international projects with strong
>> focus on semantic technologies, specifically RDF. I am also
>> working on a RDF reasoning system, called Swertia,
>> and have provided input to the RDF 1.1 Semantics CfI
>> based on this system.
>>
>> I am currently employed by the Derivo GmbH, Germany,
>> which is a small company specialized in products and
>> services based on semantic technologies. Since May 2013,
>> I have been permanently working for our business partner SAP,
>> doing work entirely dedicated to semantic technologies,
>> particularly RDF, SPARQL, and OWL. I am also currently a
>> guest scientist at FZI Research Center for Technologies,
>> Germany, where I have been working in the past for more
>> than five years, and a doctorand at the Karlsruhe Institute
>> of Technology (KIT), working specifically on reasoning in
>> expressive extensions of the RDF Semantics.
>>
>> == References ==
>>
>> [01] RDF 2004 Semantics <http://www.w3.org/TR/2004/REC-rdf-mt-20040210/>
>> [02] RDF 1.1 Semantics PR <http://www.w3.org/TR/2014/PR-rdf11-mt-20140109/>
>> [03] LCWD comment on ISSUE 165 <http://lists.w3.org/Archives/Public/public-rdf-wg/2013Oct/0221.html>
>> [04] CR comment on ISSUE 165 <http://lists.w3.org/Archives/Public/public-rdf-comments/2013Dec/0027.html>
>> [05] Resolution of ISSUE 165 <http://lists.w3.org/Archives/Public/public-rdf-comments/2013Dec/0107.html>
>> [06] RDF WG Charter <http://www.w3.org/2011/01/rdf-wg-charter>
>> [07] <http://lists.w3.org/Archives/Public/public-rdf-comments/2013Oct/0083.html>
>>
>
>
> ----
> Ivan Herman, W3C
> Digital Publishing Activity Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> GPG: 0x343F1A3D
> FOAF: http://www.ivan-herman.net/foaf
>
>
>
>
>
Received on Wednesday, 26 February 2014 22:17:39 UTC

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