Notes on computational linguistics.pdf - UCLA Department of ...

Stabler - Lx 185/209 2003
Exercises:
To begin, download our implementation of the CKY recognizer from the web page. (This implementation
has several files, so download them all into the same directory, and run your prolog session in that directory.)
1. a. Modify g1.pl so that it generates exactly the following tree:
cp
deg
almost
dp
d0
every
d1
np
n1
n0
person
cp
c1
c0 ip
np
p0
at
pp
p1
d0
the
dp
d1
np
n1
n0
premiere
i0
will
v0
glitter
i1
vp
v1
v0
coord
and
emph
so
v0
sparkle
cp
c1
c0 ip
dp
Mog
v0
whips
i1
i0 vp
pp
p1
p0
out
v1
dp
her
dp
ap
a1
a0
silvered
np
np
n1
n0
sunglasses
(Notice that this grammar has left recursion, right recursion, and empty productions.)
b. Use your modified grammar with the ckySWI recognizer to recognize the string as a cp:
so every silvered premiere will sparkle
Turn in (a) the modified grammar and (b) a session log showing the successful run of the ckySWI parser
with that sentence.
Extra Credit: That last exercise was a little bit tedious, but we can automate it!
a. Download the file wsj_0009.pl, which has some parse trees for sentences from the Wall Street Journal.
b. Write a program that will go through the derivation trees in this file and write out every rule that would
be used in those derivations, in our prolog grammar rule format.
c. Take the grammar generated by the previous step, and use ckySWI to check that you accept the strings
in the file, and show at least one other sentence this grammar accepts.
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