[topicmapmail] Topic Maps and Natural Language processing

[Dan Corwin]

Nice job, Steve.  Your analysis seems right on track.

For PSIs and extra background on the thematic role types,
I would suggest this hybrid model, which moves Conceptual
Graph models into the Topic Map formalism:

   http://www.lexikos.com/psi/ctm/index.jsp

A few basic situation types, straightforward to extend for
any specific domain of discourse, are cited as whole-part
association sub-types.

FYI: We have built a small, pure-Java search engine product
that indexes such associations.  Anyone with good use cases,
or who can help me map paragraph text to them, RSVP offline.

Regards,
Dan Corwin


Steve Pepper wrote:
> * Chattun Lallah wrote
> |
> | I am trying to represent an event which involves some
> | natural language constructs into topic maps. I have not
> | been able to find a solution how to represent language
> | semantics.
> 
> This is an interesting question that deserves more research in
> the Topic Maps community. (Idea for a masters thesis, perhaps,
> or a presentation at TMRA?)
> 
> The short answer is that it *can* be done, but it would probably
> be worth developing conventions based on accepted principles of
> linguistic semantics, such as thematic roles, etc.
> 
> Let me try to walk through how it could work. Here's what we
> want to represent as a topic map:
> 
> | "Number 10 denied that Gordon Brown exploited Lady Thatcher for
> | political ends by inviting her to Downing Street."
> 
> The core semantic relation that needs to be expressed here is
> the (alleged) exploitation of her Ladyship by GB. So there are
> two primary actors, for which we define topics (of type person):
> 
>   /* LTM fragment. Can be loaded in the Omnigator */
>   [person   = "Person"]
>   [brown    : person = "Gordon Brown"]
>   [thatcher : person = "Lady Thatcher"]
> 
> The semantic relation is exploitation, which we define as an
> association type with two corresponding role types. Here I use
> fairly generic role types which I also used for the Killed by
> relationship in the Italian Opera Topic Map:
> 
>   [exploitation = "Exploitation"
>                 = "Exploited by" / victim
>                 = "Exploited" / perpetrator] /* association type */
>   [perpetrator  = "Perpetrator"]             /* role type */
>   [victim       = "Victim"]                  /* role type */
> 
> (Note that I give the association type multiple names in scopes
> corresponding to the role types in order to get appropriate labels.)
> Now we can create an association to represent the core semantic
> relation:
> 
>   exploitation( thatcher : victim, brown : perpetrator )
> 
> Put all that together and you can browse it as a little topic
> map in the Omnigator.
> 
> Now, I don't know who made this assertion, but it wouldn't surprise
> me if it was a certain rag that I personally don't trust very
> much. If you want, you can scope the association to capture this:
> 
>   exploitation( thatcher : victim, brown : perpetrator )
>     / daily_mail
> 
>   [newspaper = "Newspaper"]
>   [daily_mail : newspaper = "Daily Mail"]
> 
> So far, so good. Now we want to say something about the *means*
> by which the exploitation took place ("Invitation to Nr. 10"),
> so we need a topic to represent that subject:
> 
>   [means = "Means"]
>   [nr10invite : means = "Invitation to Nr. 10"]
> 
> I choose to capture the additional knowledge by adding a third
> role to the association (this is a design choice that might be
> worth discussing; there are alternatives):
> 
>   exploitation( thatcher : victim,
>                 brown : perpetrator,
>                 nr10invite : means )
>     / daily_mail
> 
> We have now captured the full semantic relation as an association.
> What we want to do next is annotate it to capture Nr. 10's denial.
> To do that we have to *reify* the association, as follows:
> 
>   exploitation( thatcher : victim,
>                 brown : perpetrator,
>                 nr10invite : means )
>     / daily_mail
>     ~ thatcher-exploitation
> 
> This gives us a topic to represent the relationship. Let's give
> the topic a name and a type, for readability:
> 
>   [act = "Act"]
>   [thatcher-exploitation : act
>      = "Mrs. Thatcher exploited by Gordon Brown"]
> 
> (In the Omnigator reification is shown by the text "More..."
> Clicking on it makes the reifying topic the current topic.)
> 
> Now we have your "cloud of topics" represented by a single reified
> association, and all we have to do is add an additional ("Denial")
> association, which we can say involves an act and a denier:
> 
>   [denial    = "Denial"
>              = "Denied by" / denier
>              = "Denied" / act ]
>   [denier    = "Denier"]
> 
> The association representing Nr. 10's denial then looks like this:
> 
>   [institution = "Institution"]
>   [nr10 : institution = "Nr.10"]
> 
>   denial( thatcher-exploitation : act, nr10 : denier )
> 
> And there you have it.
> 
> The key, of course, is to use reification in order to make it
> possible to annotate (say more about) the relationship represented
> by the association.
> 
> Two final points:
> 
> (1) While this topic map looks OK in the Omnigator, a couple of
> things are left to be desired:
> 
> * It would sometimes be useful to be able to see the role types
>   clearly when you have an n-ary association. (You can see them
>   if you mouse-over the role player, but that's not as intuitive
>   as it could be.)
> 
> * It would be even more useful to see the role types when looking
>   at the topic that reifies the association (under "Reification
>   Topics").
> 
> * It's not really necessary to display "More..." twice for the
>   same association; once would be enough.
> 
> (2) I haven't given a lot of thought to the role types used in
> this example. It would be worth investigating the usefulness of
> one or more of the sets of "thematic roles" [1] that have been
> proposed in semantic linguistics (e.g. agent, author, instrument,
> patient, benefactive, experiencer, theme, source, goal, locative,
> reason, and purpose).
> 
> I hope this answers your question, Chattun. I've kept it fairly
> simple, but it would be possible to go further and capture
> stuff like tense and aspect. However, Topic Maps wasn't really
> designed to do that, so I'm not sure I'd advise it.
> 
> Steve
> 
> [1] A.k.a. semantic cases (Fillmore), semantic roles (Dillon),
> thematic relations (Gruber, Jackendoff), and (sort of) theta
> roles (Chomsky, Marantz).
> 
> --------
> 
> COMPLETE TOPIC MAP
> 
> [person   = "Person"]
> [brown    : person = "Gordon Brown"]
> [thatcher : person = "Lady Thatcher"]
> 
> [exploitation = "Exploitation"
>               = "Exploited by" / victim
>               = "Exploited" / perpetrator] /* association type */
> [perpetrator  = "Perpetrator"]             /* role type */
> [victim       = "Victim"]                  /* role type */
> 
> [newspaper = "Newspaper"]
> [daily_mail : newspaper = "Daily Mail"]
> 
> [means = "Means"]
> [nr10invite : means = "Invitation to Nr. 10"]
> 
> exploitation( thatcher : victim,
>               brown : perpetrator,
>               nr10invite : means )
>   / daily_mail
>   ~ thatcher-exploitation
> 
> [act = "Act"]
> [thatcher-exploitation : act
>    = "Mrs. Thatcher exploited by Gordon Brown"]
> 
> [denial    = "Denial"
>            = "Denied" / denier
>            = "Denied by" / act ]
> [denier    = "Denier"]
> 
> [institution = "Institution"]
> [nr10 : institution = "Nr.10"]
> 
> denial( thatcher-exploitation : act, nr10 : denier )
> 
> 
> _______________________________________________
> topicmapmail mailing list
> topicmapmail at infoloom.com
> http://www.infoloom.com/mailman/listinfo/topicmapmail
> 
>