Type identity

[Detmar Meurers]

Hi Viktor,

> Correct me if I am wrong, but the way I conceptualized them, typed
> feature structure frameworks do not offer a straightforward
> interpretation for type equality.

Assuming that by typed feature structure frameworks you mean HPSG
(Pollard and Sag 1994), this is wrong.  As I wrote in my previous
email, adding the syntax to express type equality to an attribute
value logic like SRL or RSRL is relatively straightforward. But I
think I see where your objection comes from:

The confusion seems to arise from the fact that when we model
language (rather than knowledge about language), every model of a
linguistic object by its nature is of a most specific type. So types
which aren't most specific don't actually have a life of their own
in the denotation, i.e., in the side we describe using the syntax of
our constraint language (which makes up our linguistic theory).

But when we talk about adding statements to express type equality,
we talk about adding a new piece of syntax. Those pieces of syntax
naturally need to be interpretable, but a type is denotationally
equivalent to the disjunction of its most specific subtypes. So all
that happens is one adds the syntax expressing type equality and
defines its denotation in terms of a set of pairs of most specific
subtypes.

Lieben Gruß,
Detmar

--
Detmar Meurers                              Fax: Int + 614 292-8833
The Ohio State University                   Tel: Int + 614 292-0461
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"It is a capital mistake to theorize before one has data. Insensibly
one begins to twist facts to suit theories, instead of theories to
suit facts." Sherlock Holmes in "A Scandal in Bohemia" (A. C. Doyle)