Assignment 8, Ling 645/CMSC 723, Fall 1997
Assignment 8, Ling 645/CMSC 723, Fall 1997
SELECTION RESTRICTIONS AND CONSTRAINT SATISFACTION
Do 8.1 and 8.2, and ONE of 8.3 or 8.4. (I'd prefer you did both, but
that's optional. I'll choose the higher grade if you do both.)
8.1 Copy the type hierarchy on Allen, p. 306, and add the following
word senses
BACHELOR/PERS is-a PERSON
BACHELOR/SEAL is-a ANIMATE
BALL/ROUND is-a PHYSOBJ
BALL/PARTY is-a EVENT
ACTION is-a ALL
MOTION-ACT is-a ACTION
SOCIAL-ACT is-a ACTION
PSYCH-ACT is-a ACTION
THROW/PHYS is-a MOTION-ACT
THROW/SOC is-a SOCIAL-ACT
THROW/PSYCH is-a PSYCH-ACT
TANTRUM is-a PSYCH-ACT
ADMIRE is-a PSYCH-ACT
ABSTRACTION is-a ALL
TIME is-a ABSTRACTION
SINCERITY is-a ABSTRACTION
(a) Identify the thematic roles for THROW/PHYS, which refers
to physically throwing an object through the air,
THROW/SOC, which refers to "throw" in the sense of throwing
a party, and THROW/PSYCH, which refers to "throw" in the
sense of throwing a tantrum or throwing a fit. Refer to
a dictionary and/or a native speaker of English if you're
not clear on the meanings, or send me e-mail. [6 points]
(b) Write selection restrictions (in Allen's format) for each of
the three senses of "throw", using the taxonomy you drew as your
set of possible selection restrictions. [6 points]
(c) Write a QLF using an event-variable and thematic
roles, for the sentence "The bachelor threw a ball".
(You may assume the obvious semantics and word senses
for the words in this sentence, as per Allen's usual stuff.)
Convert it to the "flat" form as done in class (see Allen,
p. 297-99). [8 points]
(d) Apply the constraint satisfaction algorithm of p. 299
to the resulting unary and binary relations, using the
selection restrictions from part (b) and the extended
taxonomy from above. Show your trace of the algorithm
and the resulting valid sense assignments for the variables.
[15 points]
(e) Extra credit [5 points]: Assuming a QLF encodes only word
sense ambiguity, i.e. there are no unscoped quantifiers, sketch
a method for enumerating all the possible LF's. Feel free
to assume whatever you like, e.g. that the constraint satisfaction
algorithm records a trace of its behavior as in part (d), or
even that you simply have the output of the algorithm. (This
is a thought question: I have not solved it.)
8.2 In this problem you're going to take a look at what it's like
to think about selectional restrictions in a "non-toy" context.
Create a directory called hw8 and go into it:
mkdir hw8
cd hw8
Retrieve file umiacs.umd.edu:pub/resnik/ling645/hw8.tar.gz
ftp umiacs.umd.edu
[Log in as anonymous, give your e-mail addr as password]
cd pub/resnik/ling645/hw8
mget *
[Say yes to each question]
quit
Uncompress the data file
gunzip OT.txt.gz
Make 'concord' executable
chmod a+x concord
(a) "Concord" is a simple concordance program; that is, a program that
goes through a text and shows you all the contexts in which
a given word appears. OT.txt is the full text of the Old Testament.
As an example, if you want to look at all the occurrences of
the word "young", you can type
concord "young" < OT.txt | more
Note that you also get back some lines containing "younger"
or "youngest".
Based on the concordance lines for "young", do you see
one word sense or many? Identify the sense or senses you
see and write a plausible selectional restriction for the
thing it modifies. [5 points]
(b) Try looking at the concordance lines for the verb "drink".
Note that you'll need to look not only for "drink" but also
for its verb inflections ("drank", "drunk"), and notice that
you'll get back irrelevant lines, e.g. where "drink" is used
as a noun. Based on what you see, what would you specify
as selectional restriction for the THEME of DRINK? Would
this change if you were going to interpret selection restrictions
as constraints that could have exceptions? Justify your
answer by examples. [10 points]
Note that if you want wider concordance lines, you can change
the number 30 in "concord" to a larger number, e.g. 35 or 40.
Your screen and font size will determine how large the number
can be and still display properly.
REMEMBER: YOU DON'T HAVE TO DO BOTH OF 8.3 AND 8.4. If you need more
practice on the constraint satisfaction algorithm, do 8.3. To explore
selection restrictions further, do 8.4.
8.3 Add the following selection restrictions to the knowledge above.
(EXPERIENCER ADMIRE PERSON)
(THEME ADMIRE ALL)
Consider the following QLF, for "The sincerity admires the bachelor"
(EXISTS e
(& (ADMIRE e)
(THEME e <THE b : ({BACHELOR/PERS,BACHELOR/SEAL} b)>)
(EXPERIENCER e <THE d : (SINCERITY d)>)))
Do the "flattening" step of 8.1(c) and then apply the constraint
satisfaction algorithm. Show your trace of the algorithm
and the resulting valid sense assignments for the variables.
[15 points]
8.4 Return to the concordance in problem 8.2 This time, try it for
the verb "buy". (Again, remember to look at all inflections.) Do you
see one sense of "buy" used, or more? If more than one, explain. For
each such sense (possibly just one!), identify a set of thematic roles
and selection restrictions for those roles, and give an example
for each. [15 points]
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