Global constraints [Was: "Generative" serves them right]

[Carl Pollard]

Hi Paul,

You're up late (not as late as me though).

Well put (your reply to Emily, I mean). In terms of HPSG2/3, total
well-typedness is something that can be enforced locally (i.e. at each
node of a feature structure).  If structures were bars and features to
be checked were bar patrons, it would be like making sure everyone in
the joint is at least 21, the bouncer only has to check each person's
ID as s/he enters. Of course, there ARE constraints used in HPSG that
are not local in this sense, for example the way Adam Przepiorkowski
deals with wh-binding using RSRL (am I remembering this right, Adam?)
Imagine a bar where you get kicked out at midnight if there is not
someone else in the bar with the same birthday. That is a global
constraint, in a certain sense.

But global constraints like the ones in MP or OT are global in a much
different sense, because they require that the well-formedness of a
given (completely specified) structure be determined relative to other
structures in some (usually not very clearly defined) comparison
class. Imagine a bar B where the whole joint is forced out of business
if there is a customer X in B such that there is another customer Y in
some OTHER bar, somewhere, anywhere, who has the same birthday as X
but a cooler haircut.

Carl