[developers] PCFG

Stephan Oepen oe at ifi.uio.no
Thu Oct 13 09:14:55 CEST 2011

hi montse,

there are two parts of PET that can in principle take
advantage of a PCFG, but i would guess you are here
interested in enabling the ‘chart pruning’ facilities
(contributed by bart and yi), for better efficiency?

from what i recall, the PCFG needs to be declared in
the grammar settings, e.g. something like

 gm := tibidabo.pcfg.

one should then see messages about the file being
loaded into PET at start-up.  to actually activate
chart pruning, use the -cp command line option.  it
takes as an optional argument the limit to impose,
where the default is 400 (passive edges per span),
i believe.

i believe there should even be an cpu definition for
the SRG in the LOGON tree, with chart pruning on.
please look for :srg/cp (or something similar, i am not
fully on-line just now).  assuming there is such a cpu,
one can then

 ./parse --binary --srg/cp ...

i would be curious to hear more about your experience
with chart pruning.  i think dan had maybe found that
substantial spped-ups are available without much loss
in accuracy.  but also that chart pruning could make it
a little more expensive to maintain treebanks across
grammar revisions, owed to an additinal element of
fluctuation about what top-500 trees are recorded in
each profile.

all best, oe

On Thursday, October 13, 2011, Montserrat Marimon <montserrat.marimon at ub.edu>
> Hola!!!
> does anyone know how to use the "file.pcfg"? I know how to create it, but
I don't know how to use it with the "parse" command.
> Thanks,
> --
> Montserrat Marimon
> Departament de Lingüística General
> Facultat de Filologia - Universitat de Barcelona
> Edifici Josep Carner, 5a planta
> Gran Via de les Corts Catalanes, 585
> tel.: + 34 93 4034695
> http://stel.ub.edu/linguistica-ub/

+++ Universitetet i Oslo (IFI); Boks 1080 Blindern; 0316 Oslo; (+47) 2284
+++    --- oe at ifi.uio.no; stephan at oepen.net; http://www.emmtee.net/oe/ ---
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