TOTAL STRAW DRAFT

Version as of December 5, 2006. (Ignore in favor of the latest version, as of March 26, 2006.)

This is an attempt by me, Bijan Parsia, with feedback from various others, including members of public-owl-dev, to draw up a charter for a scoped, successor WebOnt working group. I welcome feedback, but prefer it to be directed to the mailing list.

I'm trying to write a charter that is sufficiently scoped so that the working group is constrained to a relatively small, predictable addition to OWL. I personally want this for several reasons:

• As an implementor, expert, and tool guy, I hear a  lot of "we need qualified number restrictions", "Should I use OWL Lite?", and "Why can't I use the Dublin Core ontology with OWL DL?" Of course, I also hear, "How about rule support?", "Database integration!", and "How about nonmonontonic inheritence?" (Ok, the last not so often :)). The difference for me between the former and the latter is the former are more semantically and implementationally uncontroversial (though, punning and annotations are possibly dodgy), and I know enough high profile, high value users who would, in fact, use the particular varients that we can easily build consensus and implementations around. So, I would like to implement support for them in an interoperable and standardized way.
• While people have mentioned worries about disturbing the OWL and Semantic Web ecology by somehow sending the message that "OWL is broken" or "Wait for the new and better OWL before adopting", I think there is a converse worry, that OWL should appear to be stagnent, and/or that persisting missing functionality (esp. QCRs and Datatypes) will drive important users away from OWL. Clearly, neither consideration is conclusive since they are both predicated on rather tenuously based predictions. However, I hope that this working group will balance the concerns. By being scoped and incremental and fast, I hope it can avoid any untoward destabilization. Old OWL will still be good OWL. Having major tool builders on board also helps a lot. (I think we'll get some new vendors too, esp. given the tractable fragments document.)
• I dearly hope this is not the last increment/addendum/change to OWL. I hope this group can set the bar for useful, careful additions to be quite low. At the moment, afaict, there's no (other) plan or intention for adding to OWL. Given the wealth of interesting and useful extensions being developed, the postponed issues, and the partially met or unmet goals of Webont (not to mention the goals they left out!), it seems clear that just punting is a non-starter. I'd like there to be a clear way forward.
• Some things can be and perhaps properly are handled by other groups, such as the RIF (for rules; though really, the RIF is about interchange of rules and what some OWL users want is an OWL rules language, which might then have a corresponding RIF dialect), or the DAWG (for conjunctive query). But other things really seem to require attention on OWL itself (such as  QCRs, axiom annotations, and the like).
• I would like OWL to be a bit more XML friendly, on the one hand, and human reader friendly, on the other. I think these can help adoption a lot by reaching into new user communities.
• Logic based KR has a lot to offer that OWL or OWL DL (and, by extension, OWL 1.1) doesn't offer. There are competitors, both standardized or standardizing (e.g., Common Logic) or not (F-Logic), that are worthy of respect and investigation. There are choices running fairly deep in OWL (and OWL DL) that make synthesis with these other languages, at least as they are commonly implemented and deployed, fairly nontrivial. In fact, there is ongoing research on this. I don't want this working group to address any such issues, mostly because I don't, at the moment, as a tool developer, see how to support what I imagine the resulting specs to be in any reasonable time frame for a reasonable (and likely) level of investment. Heck, I don't see how to specify such in a reasonable time frame for a reasonable level of investment.
• I would like the working group to finish in short order. So, I'm trying to make the charter such that the wg doesn't go off into the weeds (my experiences with WSDL and DAWG loom; even WebOnt and RDF Core are cautionary). On the other hand, I've been on the short end of a charter fight where, really, we could just fix something or add something really useful, but "the charter doesn't allow it", while not typically actually a show stopper, makes it all very unpleasant and tedious. I would like the charter to be helpful to the group, not annoying to it, and helpful to reaching completion in a short time frame.

These are the sort of thing running through my head as I try to craft a charter.

[NewWebOnt] Working Group Charter

Modified from WS-Policy charter

The mission of the [NewWebOnt] Working Group, part of the Semantic Web Activity, is to produce W3C Recommendations for an extension to the Web Ontology Language (OWL) by refining the “OWL 1.1” Member Submission, addressing implementation experience and interoperability feedback from the specifications, maximizing compatibility with existing ontologies, documentation, practices, and implementations.

OWL 1.1 grew out of the first OWL: Experiences and Directions (OWLED) workshop. It represents a relatively small extension of the OWL DL sub-language that 1) were identified by users as widely needed and 2) were identified by tool implementors as reasonable extensions to current tools. At the second OWLED workshop, there were multiple implementations of editors and reasoners for OWL 1.1, validating the design. Users at the workshop indicated that this relatively small addition to OWL DL would address a wide class of needs and help further adoption of OWL.

OWL 1.1 also tried to rationalize certain aspects of OWL based on user and implementor experience. For example, it brings OWL DL and OWL Full closer together (by extending OWL DL's metamodeling capabilities) and offers a set of fragments of OWL DL that are truely "light" but useful. Also, the somewhat convoluted abstract syntax has been streamlined and a transliteration to an XML concrete syntax is provided, while the mapping to RDF graphs has been made clearer (as well as extended to the new features).

This Working Group shall be schedule-driven and OWL 1.1 shall remain compatible, to the extent possible, with existing implementations and uses. This charter features an aggressive schedule and a tightly constrained scope designed to ensure that the [NewWebOnt] will meet its schedule. This charter is intended to carry OWL consensus and interoperability forward, as outlined in Tips for Getting to Recommendation Faster.

Scope

The [NewWebOnt] workin group is chartered to provide an incremental extension to the Web Ontology Language (OWL). The extensions are of the following sorts:

• Extensions to the logic underlying OWL, in particular, with new constructs that extend the expressivity of OWL (e.g., qualified cardinality restrictions). In particular, these extensions move OWL from drawing constuctors from the description logic SHOIN(D) to drawing constructors from the description logic SROIQ(D).
• Changes to the specification of the syntax and semantics of OWL. In particular, rationalization and tigher specification of the abstract syntax of OWL to better support APIs and specification of the semantics and a round-tripable, determinisitc mapping from the abstract syntax to RDF graphs.
• Additional concrete sytnaxes for OWL ontologies. Notably, a new XML format designed for easy parsing and maximal compatibility with current XML practices. The XML format can be converted to the corresponding RDF syntax with a straightforward XSLT.
• Rationalization of the species of OWL. OWL DL and OWL Full are moved closer together (that is, more OWL Full ontologies are "DLable" with current technology). Also, there are several new "lite" versions of OWL which have better worse case complexity than OWL DL or Full (or OWL 1.1) and are particularly designed to be efficiently implementable with standard relational and deductive database technology.

The starting place for the working group is the OWL 1.1 member submission. It defines expressive extensions for OWL DL, new abstract syntax, new XML syntax, and a mapping from the new syntax to RDF as well as a set of "lighter" fragments of OWL. In order to aid the working group in staying on schedule, this charter requires working group consensus to add expressivity to OWL beyond that in the OWL 1.1 member submission. The charter does not require working group consensus to remove some of the additional functionality if it turns out to have unanticipated difficulty. This charter also does not require working group consensus to add additional concrete syntaxes (e.g., more "user friendly" syntaxes), or additional fragments to the species of OWL so long as these additions do not interfere with the progress of the working group. No such additions over the member submission should be justification for an extension of the working group's lifespan. [ed...is this a good idea?]

The working group will work to ensure a smooth transition from OWL to OWL 1.1 by providing suitable outreach documents (whether new or as updates to existing documents), and by striving to maximize compatibility, especially of ontologies.

The working group will develop an extension to the OWL Test Suite covering new functionality (and optionally old functionality), and differences, if any, with the existing language.

Out of Scope

• Conjunctive query (see the DAWG for SPARQL/DL)
• Perhaps a WG submission?
• Rules
• Lobby the RIF
• A WG would help keep OWL "in mind" for the RIF
• Radical cool new features (Yes, I have a list I want too)

Dependancies

• RIF
• DAWG?

Meetings

The [NewWebOnt] will have distributed but no face-to-face meetings.

At least up until the Last Call period ends a two-hour Working Group distributed meeting will be held every week. Thereafter, a one and half hour Working Group distributed meeting will be held every week. When necessary to meet agreed-upon deadlines, distributed meetings may be held twice a week.

The [NewWebOnt] Working Group may adjust the timing and duration of meetings to address the workload and assure that the goals and schedule of this charter are achieved.

Deliverables

• Syntax and Semantics (S&S)
• Mapping to RDF
• XML Syntax
• Outreach material 
• Guide, Overview, Reference
• update/diff//what the wg decides
• Tractable Fragments document
• Test Suite

Schedule