[developers] How to unify a type constraint onto a dag extracted (LKB)

[Berthold Crysmann]

Dear fellow sea mammals,

I have a hook function that converts internal feature structure 
representations of tone and length into diacritically marked surface 
strings for generator output.

For some very good reason that is a bit hard to explain, I need to 
synchronise tone and length lists in length at maximal words, in order 
to enforce latent tonal constraints.

In the grammar, this is done by way of constraining dtrs in syntax rules 
to have a SUPRA value of type supra_reent  which
introduces the necessary reentrancies.

During unpacking such constraints are not enforced on the daughter 
edges. That's why I need to unify this constraint in by way of the 
function call. See code below.

However, although I can test that the new type is indeed supra_reent, 
the associated constraints do not seem to get unified in. I.e. the lists 
that this type equates are apparently not equated, as I can tell from 
the underspecified list values. If I unify the supra_reent type into the 
chart edge using  the CLIM interface, list elements get xspecialised as 
expected.

Here's the  code that I have tried:

             (setf supra
              (unify-dags
               (get-dag-value (tdfs-indef (edge-dag daughter))
                      'SUPRA)
               (create-typed-dag 'SUPRA_REENT) )

              )

Thanks a lot in advance for your replies. I guess I am just calling the 
wrong function, but which one to call instead?


Cheers,

Berthold

-- 
Berthold Crysmann<crysmann at linguist.jussieu.fr>
CNRS, Laboratoire de linguistique formelle (UMR 7110), U Paris Diderot
Case 7031, 5 rue Thomas Mann, 75205 Paris cedex 13
Bureau 545, bâtiment Olympe de Gouges, rue Albert Einstein, 75013 Paris