LING 388Language and Computers

Take-Home Final ExaminationTake-Home Final Examination

12/912/9/03/03

Sandiway FONGSandiway FONG

Administrivia

Final Lecture Today:Final Lecture Today:

1.1. Topic ReviewTopic Review

2.2. Final Exam Final Exam Review of questionsReview of questions Ask clarification questions!Ask clarification questions!

3.3. Class SurveyClass Survey Office Hours (TA):Office Hours (TA):

This Friday 11-12:15 pm in Social Science 224 (the This Friday 11-12:15 pm in Social Science 224 (the computer lab)computer lab)

Administrivia

Final Examination RulesFinal Examination Rules Due Due exactlyexactly one week from today: one week from today:

NoonNoon Tuesday 16th Tuesday 16th NoNo late submissions will be accepted late submissions will be accepted

Answers submitted must be your answersAnswers submitted must be your answers TA (Charles) and instructor (me) available by email and in TA (Charles) and instructor (me) available by email and in

person (as practical) to answer your questions about the final person (as practical) to answer your questions about the final all weekall week

Attempt as many questions as you canAttempt as many questions as you can 46 pts on offer46 pts on offer You don’t have to answer all questions to receive full credit You don’t have to answer all questions to receive full credit

(30 pts)(30 pts)

Topics Covered

Goals of the course:Goals of the course: Introduction to computational linguisticsIntroduction to computational linguistics Ability to write grammarsAbility to write grammars Hands-on approachHands-on approach

Computer laboratory classes as well as regular lecturesComputer laboratory classes as well as regular lectures

HomeworksHomeworks Designed to be extensions of computer laboratory exercisesDesigned to be extensions of computer laboratory exercises

FinalFinal Test your understanding of the lecture material and the Test your understanding of the lecture material and the

homeworks (reviewed in class)homeworks (reviewed in class)

Topics Covered

Prolog (using SWI-Prolog)Prolog (using SWI-Prolog) Data Structures:Data Structures:

Atoms, variables, lists, structuresAtoms, variables, lists, structures Programs:Programs:

Facts, program clausesFacts, program clauses

Execution:Execution: Queries, unification, rules of inferenceQueries, unification, rules of inference Non-determinism, negationNon-determinism, negation

Built-ins: Built-ins: =.., var/1, findall/3 =.., var/1, findall/3 Definite Clause Grammar (DCG) rulesDefinite Clause Grammar (DCG) rules

Topics Covered

Chomsky Hierarchy (Level 3)Chomsky Hierarchy (Level 3) Regular expressions Regular expressions Regular grammarsRegular grammars

Right and left linear grammars Right and left linear grammars Finite State Automata (FSA) Finite State Automata (FSA) Equivalence and limitations of the three Equivalence and limitations of the three

frameworksframeworks Finite State Transducers (FST)Finite State Transducers (FST)

Topics Covered

Chomsky Hierarchy (Level 2)Chomsky Hierarchy (Level 2) Context-free grammars Context-free grammars Combining right and left linear grammars Combining right and left linear grammars DCG implementation DCG implementation Push-Down Automata (PDA)Push-Down Automata (PDA) Limitations of context-free grammarsLimitations of context-free grammars

Topics Covered

Chomsky Hierarchy (Level 1)Chomsky Hierarchy (Level 1) Context-sensitive grammars Context-sensitive grammars DCG implementation DCG implementation

Stopped here …Stopped here … Did not go on to discuss Chomsky Hierarchy Level 0 Did not go on to discuss Chomsky Hierarchy Level 0

akaaka General Rewrite Rule System General Rewrite Rule System

Topics Covered

Natural Language Grammars Natural Language Grammars Definite Clause Grammars (DCG)Definite Clause Grammars (DCG)

Acceptors Acceptors Recovery of structureRecovery of structure

Multiple parsesMultiple parses Idioms Idioms Logical Form output Logical Form output Feature propagation Feature propagation Constituent agreement: local and distantConstituent agreement: local and distant

Topics Covered

Natural Language Grammars: Advanced Natural Language Grammars: Advanced TopicsTopics Tree-Walking Tree-Walking Conditions on Representation: FiltersConditions on Representation: Filters Universally Quantified ConditionsUniversally Quantified Conditions

Implemented as negated existential conditionsImplemented as negated existential conditions Multiple ConstraintsMultiple Constraints

Stopped here…Stopped here… Tools necessary to implement constraints in linguistic Tools necessary to implement constraints in linguistic

theorytheory

Topics Covered

Shallow Parsing Shallow Parsing Part-of-speech (POS) taggingPart-of-speech (POS) tagging Transformation-Based Learning (Brill)Transformation-Based Learning (Brill) Stemming (Porter Stemmer) Stemming (Porter Stemmer) Noun CompoundingNoun Compounding

Example of a difficult and unsolved problemExample of a difficult and unsolved problem

Topics Covered

Stopped here…Stopped here… Many other topics: statistical methods, ontologies, Many other topics: statistical methods, ontologies,

machine translation, document summarization, machine translation, document summarization, information retrieval, discourse processing …information retrieval, discourse processing …

There are two advanced seminars offered next There are two advanced seminars offered next semestersemester If interested, talk to me for detailsIf interested, talk to me for details

Final Examination

Final Examination

Contents:Contents: 1. Chomsky Hierarchy Level 3 (7 pts)1. Chomsky Hierarchy Level 3 (7 pts) 2. Extension of Regular Grammars (5 pts)2. Extension of Regular Grammars (5 pts) 3. Chomsky Hierarchy Level 2 (7 pts)3. Chomsky Hierarchy Level 2 (7 pts) 4. Penetrable Idioms (5 pts)4. Penetrable Idioms (5 pts) 5. Grammar Rules (10 pts)5. Grammar Rules (10 pts) 6. Prolog and Logic (6 pts)6. Prolog and Logic (6 pts) 7. Porter Stemmer (6 pts)7. Porter Stemmer (6 pts)

Question 1: Chomsky Hierarchy Level 3 (7pts)

(A) (1 pt) (A) (1 pt) Give a regular expression for the set:Give a regular expression for the set:

{ab, abab, ababab, abababab, … }{ab, abab, ababab, abababab, … } (B) (3 pts) (B) (3 pts)

Give the finite state automata for the set in part Give the finite state automata for the set in part (A) (A)

(C) (3 pts)(C) (3 pts) Write a regular grammar for the set in part (A) Write a regular grammar for the set in part (A)

Question 2: On the Extension of Regular Grammars (5 pts)

L = { aL = { annbbnn | n >= 1 } cannot be encoded by a regular | n >= 1 } cannot be encoded by a regular grammargrammar We know We know LL can be encoded using regular grammar can be encoded using regular grammar

rules plus a counterrules plus a counter We know a counter can be implemented using calls to We know a counter can be implemented using calls to

Prolog arithmetic and allowing non-terminals to take an Prolog arithmetic and allowing non-terminals to take an argumentargument

Write a DCG for Write a DCG for LL using using onlyonly regular grammar rules plus regular grammar rules plus non-terminals that take an argumentnon-terminals that take an argument i.e. no calls to Prolog arithmetic in {…} permittedi.e. no calls to Prolog arithmetic in {…} permitted

Question 2: On the Extension of Regular Grammars

Hint:Hint: Consider the following encoding of natural numbers Consider the following encoding of natural numbers

using the successor function using the successor function ss 1 = s(0)1 = s(0) 2 = s(s(0))2 = s(s(0)) 3 = s(s(s(0))) and so on …3 = s(s(s(0))) and so on …

Use this encoding in your extra argumentUse this encoding in your extra argument

Question 3: Chomsky Hierarchy Level 2 (7 pts)

Consider the following set:Consider the following set: { ww{ wwRR | w | w {a,b} {a,b}++ } } ww is a string of non-zero length of a’s and b’s is a string of non-zero length of a’s and b’s wwRR = = ww in reverse string order, e.g. (abb) in reverse string order, e.g. (abb)RR = bba = bba

(A) (5 pts)(A) (5 pts) Give a DCG grammar for wwGive a DCG grammar for wwRR

(B) (2 pts)(B) (2 pts) Is wwIs wwRR encodable using a regular grammar? encodable using a regular grammar? Explain your answerExplain your answer

Question 4: Penetrable Idioms (5 pts)

DCG rules allow idiom chunk constituents to be encoded DCG rules allow idiom chunk constituents to be encoded using one rule, e.g. using one rule, e.g. kicked the bucketkicked the bucket

However, some idioms are not completely frozen:However, some idioms are not completely frozen: e.g. e.g.

take … advantage of NPtake … advantage of NP• John took John took somesome advantage of the offer advantage of the offer• John took John took fullfull advantage of the offer advantage of the offer• John took John took goodgood advantage of the offer advantage of the offer• John took John took littlelittle advantage of the offer advantage of the offer• *John took *John took the/anthe/an advantage of the offer advantage of the offer

Write a VP idiom DCG rule for Write a VP idiom DCG rule for take ... advantage oftake ... advantage of

Question 5: Grammar Rules (10 pts)

Verb SubcategorizationVerb Subcategorization GiveGive and and donatedonate are double object verbs are double object verbs

John gave [John gave [NPNP Mary] [ Mary] [NPNP a book] a book] John gave [John gave [NPNP a book] [ a book] [PPPP to Mary] to Mary] *John donated [*John donated [NPNP Mary] [ Mary] [NPNP a book] a book] John donated [John donated [NPNP a book] [ a book] [PPPP to Mary] to Mary]

Write a DCG parser for these examplesWrite a DCG parser for these examples Show the actual output of your program for these Show the actual output of your program for these

examples along with the whole DCG,examples along with the whole DCG, i.e. use copy and paste from your Prolog systemi.e. use copy and paste from your Prolog system

Question 5: Grammar Rules

Hint: Modify the following acceptor rulesHint: Modify the following acceptor rules vp --> v, np, pp.vp --> v, np, pp. vp --> v, np, np.vp --> v, np, np. pp --> p, np.pp --> p, np. v --> [give].v --> [give]. v --> [donate].v --> [donate].

Make sure your program returns the syntactic Make sure your program returns the syntactic structurestructure

Question 6: Prolog and Logic (6 pts)

UnificationUnification (2 pts) What does the query (2 pts) What does the query

?- a(X) =.. X.?- a(X) =.. X.instantiate X to? Explain your answer.instantiate X to? Explain your answer.

NegationNegation Suppose we have the following facts:Suppose we have the following facts:

b(1). b(2). b(3).b(1). b(2). b(3). (1 pt) What does ?- b(X). return?(1 pt) What does ?- b(X). return? (1 pt) What does ?- \+ b(X). return?(1 pt) What does ?- \+ b(X). return? (2 pts) What does ?- \+ \+ b(X). return? (2 pts) What does ?- \+ \+ b(X). return?

Explain your answer.Explain your answer.

Question 7: Porter Stemmer (6 pts)

What does the Porter Stemmer output for What does the Porter Stemmer output for the following words:the following words: (2 pts) (2 pts) AvailabilityAvailability (2 pts) (2 pts) ShippingShipping (2pts) (2pts) UnbelievableUnbelievable

Show the steps in your answerShow the steps in your answer

Class Survey