RE: Trip Reports on Dagstuhl Seminar on Knowledge Graphs

Hi William,

Re your last paragraph: We use the concepts of Relationship and
ClassOfRelationship, having two predicates, instead of a Property +
InverseProperty, as classes.

So, for instance, we can model a Marriage Relationship, linking a Person to
another Person, and by typing that Marriage Relationship with a
ClassOfMarriage ClassOfRelationship. That ClassOfMarriage can have instances
like SameMaleSexMarriage linking MalePersons.

The OWL folks keep telling us that such is impossible in OWL-DL, but why
should RDF be kept hostage by that? So we keep struggling with that
unworkable reification and punning. Just a question, probably caused by my
ignorance.

Hopefully Paola doesn't shoot me to flames :))

Regards,
Hans 
15926.org
______________________________________________
-----Original Message-----
From: William Waites <wwaites@tardis.ed.ac.uk> 
Sent: woensdag 28 augustus 2019 12:37
To: Axel Polleres <axel.polleres@wu.ac.at>
Cc: Paola Di Maio <paoladimaio10@gmail.com>; Joshua Shinavier
<joshsh@uber.com>; Juan Sequeda <juanfederico@gmail.com>; Semantic Web
<semantic-web@w3.org>
Subject: Re: Trip Reports on Dagstuhl Seminar on Knowledge Graphs

> Well, link works for me, but in fact that was the pre-print version of 
> the report, the official link on the Dagstuhl page:

Thanks for the link, Axel. I have no idea why it didn't work for me earlier,
but it does now. I've read (quickly skimmed, really) the canonical version
of the report. My tuppence worth follows.

I'm a little puzzled about the Knowledge Graph. Is it a marketing term?
The question is only a little facetious: quite a few of the reports are
struggling to define what it is. We know that graphs are general structures
for representing a variety of different things, that's a very old idea and
it's very powerful (think objects and arrows). We know that going from
discrete entities (e.g. labellings) to continuous ones is hard and unobvious
so we get divisions in fields between graphs and rules on the one hand and
statistics and neural networks on the other. Plenty of potentially
productive open problems and questions lie that way.

I think what Paola might be getting at is the way that we have continually
invented new words for whatever it is we are doing here. There's the
Semantic Web, there's Linked Data, now there's the Knowledge Graph. Each
with a slightly different focus perhaps as you point out in your
presentation, but with little substantive change. That's what I mean by
marketing terms (easily recognised by the proper noun casing).

There *are* fundamental problems with RDF. The main one is that it is
impossible to coherently make statements about statements. Without that, we
can't build hierarchies of statements and things like time and provenance
and the like (mentioned in the report) can't be done. These are important
and fascinating areas to research, but those areas remain out of reach for
SW/LD/KG so long as the underlying RDF doesn't change to allow it. And so,
we are stuck. We can fix it, or we can keep inventing new names.

Best wishes,

William Waites | wwaites@inf.ed.ac.uk
Institute for Language, Cognition and Computation School of Informatics,
University of Edinburgh

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Received on Friday, 30 August 2019 10:36:41 UTC