Re: Hello, n3

Hi all,

I am also really happy to see the N3 ball rolling and thanks for that!

My short bio is:

- Master of Science (ir.) at KU Leuven plus doctoral study on image
computing
  (and meanwhile building 5 wind turbines http://josd.github.io/rotor.html).
- Co-founder of ICOS Vision Systems as R&D engineer computer vision
applications.
- Agfa HealtCare R&D engineer in the successive areas of digital medical
hardcopy,
  medical gateways, advanced clinical applications and clinical analytics.
- Developer of EYE open source at https://github.com/josd/eye .

For me N3 is a great problem solving language ;-) just taking a few
examples:

1/ Control Systems

See https://github.com/josd/eye/tree/master/reasoning/cs
where https://github.com/josd/eye/blob/master/reasoning/cs/rules-001.n3
contains rules for simple feedforward control and PND feedback control.

2/ Leg Length Discrepancy Measurement

See https://github.com/josd/eye/tree/master/reasoning/lldm
and http://www.agfa.com/w3c/2002/10/medicad/op/
where https://github.com/josd/eye/blob/master/reasoning/lldm/lldmP.n3
contains rules to do the actual data processing and to detect wether one
has a leg length discrepancy.

3/ Multi-Agent Proofs

See https://github.com/josd/eye/tree/master/reasoning/map
Multiple agents can work together by using their own knowledge/logic/data
and proofs made by other agents.
The proofs are guaranteeing a transparent and accountable way of working
and they only disclose what is relevant, so there is no need to have an
"All knowledge is contained in here" (what I learned from Tim Berners-Lee).

We have a open source implementation called EYE (standing for "Euler Yet
another proof Engine") which is a N3 semibackward chainer.
Semibackward chaining is backward chaining for rules using <= in N3
and forward chaining for rules using => in N3.

The above 3 examples are from a collection of concrete reasoning examples
available at https://github.com/josd/eye/tree/master/reasoning .

For more details about how we use N3, I would like to point to the paper
"Drawing Conclusions from Linked Data on the Web: The EYE Reasoner"
available at http://josd.github.io/Papers/EYE.pdf .


Personally I'll commit time (spare time and holidays) to help resolve
n3-dev design issues, adapt EYE so that it implements n3-dev group
consensus,
contribute test cases and help define exit criteria to declare victory for
the
n3-dev group.

I really look forward to work together with you all to realize the
full potential of N3 :-)


Kind regards,
Jos

-- https://josd.github.io/ <http://josd.github.io/>


On Fri, Nov 30, 2018 at 12:48 PM Doerthe Arndt <doerthe.arndt@ugent.be>
wrote:

> Dear Nathan, all,
>
> Thank you for pushing this forward!  I am really happy that you are as
> enthusiastic about this topic as I am. I always wanted to push forward the
> formalisation of N3, so I guess, now is the time.
>
> A little bit more about my and our background:
>
> I have a master in Mathematics and I am currently finishing my PhD in
> Computer Science which has N3 and its applications as a topic. I work at
> imec in Gent (Belgium) and there, we had many research projects using N3
> and the EYE reasoner (I am sure Jos will tell us more about his
> implementation in another mail, till then you can already check
> http://eulersharp.sourceforge.net/ and http://n3.restdesc.org/).
>
> Some example projects :
>
>    - We implemented owl-rl rules in N3 and used it for ontology reasoning
>    (maybe an idea to also test it on the work of you, William, but that is
>    just a side note :) ). What was special about N3 here was that N3 allows
>    rules in the consequence of rules ( like {?C1 rdfs:subClassOf  ?C2}=>{ {?x
>    a ?C1}=>{?x a ?C2} }.). We used this for preprocessing. [1]
>
>    - We also had several projects in which we used the fact that Cwm and
>    EYE both can produce proofs. We created a format to describe possible
>    restful Web API calls in forms of rules with existential variables in the
>    consequence (another nice feature of N3), RESTdesc. The user can then give
>    a goal he or she wants to reach and by producing a proof the computer
>    provides a plan  how this goal can be reached. [2,2a]
>
>    - We used N3 for data validation. Here, we used a lot of the built-ins
>    of N3, but also  the RIF built-ins as they are implemented in EYE. [3]
>
> We also already worked on the formalisation of N3 and identified several
> problems which need to be fixed:
>
>    - *Implicit quantification:* When we used the reasoners Cwm and EYE,
>    we discovered, that they differed in their way of handling implicit
>    universal quantification. To give a concrete example, consider the rule:
>
>    {{?x :p :o} => {?x :p2 :o2}}=> {:a :b :c}.
>
>    Cwm interprets that as:
>
>    (∀x: p(x,o) → p2(x,o2)) → b(a,c)
>
>    EYE interprets it as:
>
>    ∀x: (p(x,o) → p2(x,o2)) → b(a,c)
>
>    The reason for that the W3C team submission is not really clear here,
>    it says that universals are quantified "on the parent formula" (see
>    https://www.w3.org/TeamSubmission/n3/#Quantifica), but it does not say
>    what exactly this "parent" is.
>
>    - *Explicit quantification: *N3 provides a way to express explicit
>    quantification (by using @forall and @forsome). An example formula is:
>
>     @forAll <#h>. @forSome <#g>. <#g> <#loves> <#h> .
>
>    which means in FOL:
>
>    ∀h: ∃g: loves(h,g)
>
>    But the spec also says that *"If both universal and existential
>    quantification are specified for the same formula, then the scope of the
>    universal quantification is outside the scope of the existentials" *(see
>    https://www.w3.org/TeamSubmission/n3/#Quantifica). So the formula
>
>    @forSome <#g>. @forAll <#h>. <#g> <#loves> <#h> .
>
>    also means
>
>    ∀h: ∃g: loves(h,g)
>
>    I at least think that this is counter intuitive (but maybe there are
>    good reasons to do it that way?).
>
>
>    -
>
> *No distinction between variables and constants: *Related to the previous
>    topic, it can be a problem that variables and constants are not clearly
>    distinguished. Look for example at the first occurence of :h in this
>    formula:
>
>    @forSome :g. :g :p *:h*.  @forAll :h. :g :loves :h .
>
>    Given the reversal of quantifiers when interpreting it (∀h: ∃g: ...)
>    it is not clear to me whether this :h is a universally quantified variable
>    or a constant.
>
>
>
>    -
> *Citation of Formulas: *We need to agree how to interpret cited graphs
>    like for example
>
>    :x :says {:s :p :o}.
>
>    I think this topic is quite challenging (for TriG, for example, there
>    was no agreement https://www.w3.org/TR/rdf11-datasets/). RDF* [4]
>    reduces such constructs to rdf reification which  unfortunately doesn't
>    solve the problem of defining a semantics since reification is excluded in
>    rdf semantics (see: https://www.w3.org/TR/rdf11-mt/#reification).
>    There are many different approaches we could follow like for example KIF
>    [5], Common Logic [6] or also make it more complex like they do in SUMO [7].
>
>
> I worked on the quantification part and published a paper in 2015 about
> that [8] (it is only a first draft which especially does not yet take the
> position of a quantifier into account) begin our discussions, till then I
> can refer to my presentation about this topic here:
> https://docs.google.com/presentation/d/1Tkh3JLuayBft63ltoeCCD68Zfa9wMFzjOz-h_xYX0PU/edit?usp=sharing
> (I enabled commenting in case you want to ask questions). I furthermore
> also did some work on formalising the proof calculus for N3, this part can
> be found in our Paper Pragmatic Proof [2a].
>
> As you see. I am really interested in writing the spec, but I am also
> willing to invest time in working on and testing implementation(s) and I am
> looking forward to having detailed discussions.
>
> I am looking forward to working with you.
>
> Kind regards,
> Dörthe
>
>
>
> [1]  D. Arndt, B. De Meester, P. Bonte, J. Schaballie, J. Bhatti, W.
> Dereuddre, R. Verborgh, F. Ongenae, F. De Turck, R. Van deWalle, E.
> Mannens, Improving OWL RL reasoning in N3 by using specialized rules, in:
> V. Tamma, M. Dragoni, R. Gonçalves, A. Ławrynowicz (Eds.), Ontology
> Engineering: 12th International Experiences and Directions Workshop on OWL,
> Vol. 9557 of Lecture Notes in Computer Science, Springer, 2016, pp. 93–104.
> doi:10.1007/978-3-319-33245-1_10. URL
> http://dx.doi.org/10.1007/978-3-319-33245-1_10
>
> [2] http://restdesc.org/
>
> [2a] R. Verborgh, D. Arndt, S. Van Hoecke, J. De Roo, G. Mels, T. Steiner,
> J. Gabarró Vallés, The pragmatic proof: Hypermedia API composition and
> execution, Theory and Practice of Logic Programming 17 (1) (2017) 1–48.
> doi:10.1017/S1471068416000016. URL http://arxiv.org/pdf/1512.07780v1.pdf
>
> [3] D. Arndt, B. De Meester, A. Dimou, R. Verborgh, E. Mannens, Using
> rule-based reasoning for RDF validation, in: S. Costantini, E. Franconi, W.
> Van Woensel, R. Kontchakov, F. Sadri,
> D. Roman (Eds.), Proceedings of the International Joint Conference on
> Rules and Reasoning, Vol. 10364 of Lecture Notes in Computer Science,
> Springer, 2017, pp. 22–36. doi:10.1007/978-3-319-61252-2_3. Available at:
> https://biblio.ugent.be/publication/8540876/file/8540882.pdf
>
> [4] O. Hartig, B. Thompson, Foundations of an alternative approach to
> reification in RDF, CoRR abs/1406.3399. arXiv:1406.3399. URL
> http://arxiv.org/abs/1406.3399
>
> [5] P. Hayes, C. Menzel, A semantics for the knowledge interchange format,
> in: IJCAI 2001 Workshop on the IEEE Standard Upper Ontology, Vol. 1, 2001,
> p. 145.
>
> [6] ISO/IEC 24707:2007 Information technology – Common Logic (CL),
> standards.iso.org/ittf/PubliclyAvailableStandards/c039175_ISO_IEC_24707_2007%28E%29.zip
> (2007).
>
> [7] C. Benzmüller, A. Pease, Higher-order aspects and context in sumo, Web
> Semantics: Science, Services and Agents on the World Wide Web 12 (2012)
> 104–117.
>
> [8] D. Arndt, R. Verborgh, J. De Roo, H. Sun, E. Mannens, R. Van de Walle,
> Semantics of Notation3 logic: A solution for implicit quantification, in:
> N. Bassiliades, G. Gottlob,F. Sadri, A. Paschke, D. Roman (Eds.), Rule
> Technologies: Foundations, Tools, and Applications, Vol. 9202 of Lecture
> Notes in Computer Science, Springer, 2015, pp. 127–143. URL
> http://link.springer.com/chapter/10.1007/978-3-319-21542-6_9
>
> Hi all, thanks for joining the n3-dev CG.
>
> Since the holiday season is fast approaching, we should perhaps aim to
> start ramping up communications and efforts from the new year.
>
> If you know anybody else who may be interested in joining, or should be
> involved, please encourage them to join the CG via
> https://www.w3.org/community/n3-dev/
>
> In the interim, please do share anything you think is pertinent, including
> related background reading and references, or anything you'd like to
> discuss. It may also be useful to start collating implementations, any
> nuances or bugs that have been found after working with the current
> specification [1] (see also [2]), also suggestions on what could be
> improved / simplified / expanded / removed.
>
> Let's all get on the same page, agree what to do, and get it done.
>
> Personally I'll commit time, discussion, spec writing, mistakes, and
> working reference implementation(s). Throughout the current decade I've
> frequently thought or said I/you/we could do this with n3, so before the
> turn of the next decade, *I want* to be using n3+rules daily, at scale,
> and will do my utmost to facilitate you all in using it for what you want
> or need too.
>
> Thanks all, and I look forward to working you all in the coming months,
>
> Nathan
>
> [1] https://www.w3.org/TeamSubmission/n3/
> [2] https://www.w3.org/DesignIssues/Notation3.html
>
> --
> Dörthe Arndt
> Researcher Semantic Web
> imec - Ghent University - IDLab | Faculty of Engineering and Architecture | Department of Electronics and Information Systems
> Technologiepark-Zwijnaarde 19, 9052 Ghent, Belgium
> t: +32 9 331 49 59 | e: doerthe.arndt@ugent.be
>
>