University of Washington: Linguistics: Ling 571: Winter 2017: Homework #1

Ling 571 - Deep Processing Techniques for NLP
Winter 2017
Homework #1: Due January 10, 2017: 11:45pm

Goals

Through this assignment you will:

Explore the basics of automatic parsing.
Begin to gain some familiarity with the Natural Language Toolkit (NLTK).
Gain some experience with the cluster and condor.

Background

Please review the class slides and readings in the textbook on context-free grammars. Also, see Section 8.3 of the NLTK Book for examples of grammars and configuration of the included parsers. We'll get to the later parts of that chapter soon.

Parsing

Create a program to parse the test sentences based on the provided grammar and analyze the results. Specifically, your program should:

Load the grammar.
Build a parser for the grammar using nltk.parse.EarleyChartParser.
Read in the example sentences.
For each example sentence, output to a file

the sentence itself
the simple bracketed structure parse(s), and
the number of parses for that sentence.

Finally, print the average number of parses per sentence obtained by the grammar.

Programming

Create a program named hw1_parse.py to perform the parsing as described above invoked as:
hw1_parse.py <grammar_file> <test_sentence_file> <output_file>
where

<grammar_file> is the name of the file holding the grammar rules in the NLTK .cfg format.
<test_sentence_file> is the name of the file holding the set of sentences to parse, one sentence per line
<output_file> is the name of output file for your system

Files

Please adhere to the naming conventions.

Test and Example Files

sentences.txt: Test sentences to parse
hw1_grammar.cfg: Test grammar to use to parse.
toy.cfg: Toy example NLTK-format grammar file. Other examples can be found on patas under /corpora/nltk/nltk-data/grammars/
toy_sentences.txt: Example set of sentences to parse with toy grammar
toy_output.txt: Example output file based on toy grammar

Submission files

hw1_parse.py: Primary program file
hw1_output.txt: Results of running your parsing program on the test sentences with the test grammar.
hw1.cmd: Condor file which drives your parser.
- Your program must run on patas using:
  $ condor_submit hw1.cmd
  Please see the CLMS wiki pages on the basics of using the condor cluster.
  All files created by the condor run should appear in the top level of the directory.
readme.{txt|pdf}: Write-up file
- This file should describe and discuss your work on this assignment. Include problems you came across and how (or if) you were able to solve them, any insights, special features, and what you learned. Give examples if possible. If you were not able to complete parts of the project, discuss what you tried and/or what did not work.
hw1.tar: Your hand-in file
- Use the tar command to build a single hand-in file, named hw#.tar where # is the number of the homework assignment and containing all the material necessary to test your assignment. Your hw1.cmd should be at the top level of whatever directory structure you are using.
  For example, in your top-level directory, run:
  $ tar cvf hw1.tar *

Handing in your work

All homework should be handed in using the class CollectIt.

Ling 571 - Deep Processing Techniques for NLP Winter 2017 Homework #1: Due January 10, 2017: 11:45pm