[developers] smallish native DMRS grammar

[Michael Wayne Goodman]

Hi Ann,

Thanks for sharing. I couldn't find the grammar at first because I was
looking in the LOGON tree instead of the separate LKB repository. If others
are searching, it's here:
http://svn.delph-in.net/lkb/trunk/src/data/dmrscomp/.

I find DMRS more intuitive and more manageable than other *MRS
representations, so it's exciting to imagine a world where that is the
primary representation output by our grammars. I'm curious to see how this
works out with some larger grammars, but I can think of a couple of
challenges (based on my discussion in Singapore:
http://moin.delph-in.net/SingaporeMrsWellformedness).

1. We don't yet have a way to represent ICONS in DMRS

2. DMRS currently can't express coindexed dropped arguments (where in MRS
the 'i' variable of two arguments is the same; perhaps this can be
represented using ICONS instead, or by (re)introducing zero-pronouns)

These are both difficulties with the resulting representation. I'm not sure
if there are other issues when implemented in the grammar. Sometime soon it
would be good to iron out these representational wrinkles. Considering
ICONS, I don't think we can just put a post-post-slash label on a link
(e.g. ARG1/NEQ/topic) because I don't think ICONS follow normal dependency
relations (Sanghoun could confirm).


On Fri, Dec 18, 2015 at 9:46 AM Ann Copestake <aac10 at cl.cam.ac.uk> wrote:

> I have just checked in to the LKB svn repo a small grammar - dmrscomp -
> and some code that extracts simple DMRSs directly from the feature
> structures produced by that grammar rather than going via MRS and RMRS.
> This is based on the mrscomp grammar (though with some clean up and
> minor extension) - there's a fairly detailed README file.  There are a
> fair number of items on the TO-DO list - possibly the most
> time-consuming one would be to make the generator code work with this
> grammar, not because there's any big problem (that I can think of) but
> because the generator is quite complicated.  There is also a promise of
> more detailed notes, which I will supply relatively soon, I hope - this
> was an interesting exercise in thinking through semantic composition.
>
> If someone would like to collaborate on trying a similar exercise with a
> larger grammar, I'd be very interested.  It would help if it were a
> grammar which already had the characteristic variable property, in which
> case I think the main part of the conversion should be fairly easy.
>
> There are a number of potential advantages in constructing DMRS
> directly, including the ability to construct a DMRS forest directly from
> a parse forest.  I would argue that it also enforces some notions of
> semantic well-formedness more directly than is possible with MRS -
> obviously including the (equivalent of) characteristic variable
> property.  The semantic `fingerprint' of constructions can be expressed
> more simply, because DMRS removes much of the redundancy of MRS.  But,
> of course, this is only interesting if we really can express everything
> we want to with DMRS.
>
> All best,
>
> Ann
>
>
>
>
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