[lkb] Generator question

[Stephan Oepen]

hi emily,

> This seems to be a problem for the generator: So long as cog-st is a
> sort (no features), the cog-st value is respected in generation. As 
> soon as we add the feature SPECI, however, the generator will ignore 
> the type of the COG-ST value.

i think your problem is strictly speaking not about the generator.  it
is important to acknowledge the difference between the grammar-internal
universe of typed feature structures and the grammar-independent world
of MRSs.  MRSs are not typed in a very interesting sense, and they have
very little accomodation for embedding of structures (i.e. recursion).

a typed feature structure

  ref-index & [ COG-ST foo ]

may correspond to an MRS variable, say,

  x42 { COG-ST: foo }

for convenience, MRS variables can have internal properties, but their
values are constrained to be atomic.  hence,

  ref-index & [ COG-ST foo & [ SPECI + ] ]

converts into

  x42 { COG-ST.SPECI + }

the process of constructing an MRS from its FS description, helpfully,
flattens out embedded structures and creates property names from paths
of feature names.  hence, even though `COG-ST.SPECI' looks a lot like
the TDL path notation, in the MRS universe it is a plain symbol, viz.
the name of that property.  there is no room for the sortal constraint
`foo' from the midst of the underlying path in that representation.

                i hope this helps clarify the issue?  all best  -  oe

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