[developers] Edge can be built interactively, but isn't in the chart

[Emily M. Bender]

Dear all,

[Cross-posted to developers and the delphinqa.]

After 16 years of teaching grammar engineering, I thought I'd found all of
the ways in which one can be in the situation of seemingly being able to
build an edge through interactive unification which isn't in the chart.
I've documented all of the ones I know about here:

http://moin.delph-in.net/GeFaqUnifySurprise

Alas, I've found evidence of a new one. Or rather: I'm in that situation
(together with a student) but none of the cases noted there apply. More
specifically, with the grammar for Meithei [mni] that can be found here:

http://faculty.washington.edu/ebender/mni-debug.tgz

If we try to analyze this sentence:

yoŋ-siŋ túm-í čá-í
monkey-PL sleep-NHYP eat-NHYP
Monkeys sleep and eat.

The LKB and ace both return no parses found. If instead of using the two
verbs (one intransitive and one transitive but with a dropped object), we
repeat either one of the verbs, we get the expected parses (with both the
LKB and ace).

yoŋ-siŋ čá-í čá-í
yoŋ-siŋ túm-í túm-í

Returning to the non-parsing sentence, and looking at the LKB's parse
chart, what's missing is the VP-T built out of applying the VP1-TOP-COORD
rule to the VP-B over čá-í and the VP over túm-í.  Puzzlingly, I can build
this edge interactively just fine. I've run out of guesses as to why it's
not showing up in the char and so I thought I'd put this puzzle out in case
other DELPH-INites might be entertained by it.

Curiously,
Emily

p.s. Discourse directed me to an earlier discussion about this, where
@johnca suggested checking that *chart-packing-p* is set to NIL. It is.

-- 
Emily M. Bender (she/her)
Howard and Frances Nostrand Endowed Professor
Department of Linguistics
Faculty Director, CLMS
University of Washington
Twitter: @emilymbender
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