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RDF: a suitable NLP KB representation (Was: Owning URIs (Was: Yet ?Another LOD cloud browser))

From: Sherman Monroe <sdmonroe@gmail.com>
Date: Tue, 19 May 2009 15:32:47 -0500
Message-ID: <e23f467e0905191332i4d41f37fof3bc7a0755639cd3@mail.gmail.com>
To: David Huynh <dfhuynh@alum.mit.edu>
Cc: Linked Data community <public-lod@w3.org>, semantic-web@w3.org
David said:

> I didn't quite express myself clearly. If you were to take the previous
> sentence ("I didn't quite express myself clearly"), and encode it in RDF,
> what would you get? It certainly is something that I said about "the thing",
> the thing being vaguely what I tried to explain before (how do you mint a
> URI for that?). The point is that using RDF or whatever other non-natural
> language structured data representation, you cannot practically represent
> "the things people say about the thing" in the majority of real-life cases.
> You can only express a very tiny subset of what can be said in natural
> language.

First off: I began as a NLP researcher seeking the holiest of holy-grails, a
method and accompaning knowledge representation formalism with enough
semantic rigor to encapsulate any NL statements or expression. What came out
of that work was the Cypher transcoder <http://cypher.monrai.com>. When I
was first intro'd to the RDF (circa 1999), and when I saw the triple format,
it reminded me of predicate calculus (which in my opinion failed the above
criteria), and so I turned my noise up at it (and called TimBL a
*lunatic*if I recall), and decided to just work on the NL processing
side (i.e.
extracting semantics from NL phrase structure) and shelf the knowledge
representation side 'til later (i.e. how to serialize the semantics once
extracted). Then four years or so later (circa 2003), I made enough headway
on the input processing side to turn attention again to the output/knowledge
representation side. That's when I was turned on to Frame Semantics, which I
immediately praised, it is by far the most expressive and elegant knowledge
representation framework for NL I have come across (although, it's been 3 or
4 years since I really looked). In short, frame semantics sees all sentences
as a "scene" (like a movie scene) and the nouns all play "roles" in that
scene. E.g. a boy eating is involved in a ConsumeFood scene, and the actors
are the boy, the utensil he uses, the food, the chair he sits in. So I
choose framesemantics as the KB model for Cypher grammar parser output.

This sent off lightbulbs for me, I went back to RDF, and saw that, low and
behold, frames can be represented as RDF, the scene types being classes, a
scene instance (i.e. the thing representing a complete sentence) being the
subject, the property is the role, and the object is the thing playing that
role, e.g:

EatFrame023  rdf:type  mlo:EatFrame
EatFrame023  mlo:eater  someschema:URIForJohn
EatFrame023  utensil  someschema:JohnFavoriteSpoon
EatFrame023  mlo:seatedAt  _:anonChair
EatFrame023  foaf:location  someschema:JohnsLivingRoom
EatFrame023  someschema:time  _:01122
EatFrame023  truthval  "false"^booleanValueType

dbpedia:Heroes(Series) rdf:type dbpedia:TVShow
dbpedia:Heroes(Series) dbpedia:showtime _:01122

_:01122 rdf:type types:TimeSpan
_:01122 types:startHour "20"^num:PositiveInteger
_:01122 types:startMinutes "00"^num:PositiveInteger
_:01122 types:endHour "21"^num:PositiveInteger
_:01122 types:endMinutes "00"^num:PositiveInteger
_:01122 types:timezone "EST"

This says: *No, John didn't eat in a sandwich in a chair in his living room
using his favorite spoon, during the TV show Heroes*. Do you still believe
RDF is incapable of expressing complex NL statements?

Second off: Even though RDF (when married with frame semantics) is capable
of expressing very complex NL sentences, it was never the intention of the
Semantic Web forerunners to create a framework for doing so, and I do not
believe that this capacity is nessassary to make RDF valuable. The question
RDF answers is fundamentally: *What happens if all the worlds databases
(e.g. Oracle, Mysql, etc databases out there) could be directly connected to
one another in a large global network, all sharing one massive, distributed
schema, and people were able to send queries to that network using a
Esperanto for SQL?* The ability of RDF to represent (not sentences but) rows
and columns of any database schema imaginable means it can deliver this
vision, and the value tied to it.

> This affects how people conceptualize and use this medium. If I hear a URI
> on TV, would I be motivated enough to type it into some browser when what I
> get back looks like an engineering spec sheet, but worse--with different
> rows from different sources, forcing me to derive the big picture myself,
>   urn:sdajfdadjfai324829083742983:sherman_monroe
>      name: Sherman Monroe (according to foo.com)
>      age: __ (according to bar.com)
>      age: ___ (according to bar2.com)
>      nationality: __ (according to baz.com)
>      ...
> rather than, say, a natural language essay that conveys a coherent opinion,
> or a funny video?

Then it seems you're still not a convert :) As for me, your example here has
very obvious value. Remember what WWW did for humans and the huge revolution
that came with giving people access to what other people in the world were
saying no matter where in the world they were, and no matter what langauge
the host machine spoke natively. The SW is doing that all over again... but
for machines this time.

User empowerment is a large external benefit of the SW, in WWW, webmaster
makes assumptions (sometimes rightly, sometimes wrongly) about what data is
important and should be shown and how, in SW, user decides for his/herself.
Additionally, NL will play a big part of cleaning up the UI so that it
doesn't look like an enginerring schematic :) Again, I reference
Notice the descriptions in the breadcrumbs and descriptions of facets under
the 'Your query' link.

Received on Tuesday, 19 May 2009 20:33:39 UTC

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