Assignment 8, Ling 645/CMSC 723, Fall 1997

Assignment 8, Ling 645/CMSC 723, Fall 1997


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

      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

     (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

	    [Log in as anonymous, give your e-mail addr as password]
	 cd pub/resnik/ling645/hw8
	 mget *
	    [Say yes to each question]

       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]

Return to the course home page.