Scope
& History
of Computational
Linguistics
|
Practical Applications
Linguistic Theory
Two Dimensions of variation
System Functionality
Semantic decision/classification systems
Knowledge extraction systems
Information Extraction systems
Command systems
Dialog systems
Translation systems
System Modality
Text
Speech
Multi-modal (primarily visual +)
Applications
Semantic Decision/classification systems
News article classification (profit/earnings article, terrorist attack article)
Sentiment detection (good/bad review; left/right political orientation)
Spam detection
Complaint classification
Knowledge extraction systems (Ontology Building)
Named entity extraction (persons, organizations,
places, events)
Clustering terms into categories
Hierarchy construction (finding the term "fruit" for the
"orange", "apple", "grape",... cluster )
Relation discovery
place/superplace
event time, temporal event/event relations
other part-whole relations (structural component, chemical constituent) [Medical, chemical weapon detection]
Information Search Systems
Database query
Bill Woods Moonrocks system (70s)
HP NL system (80s)
NLI Intellect System (Ginsparg, 90s)
Microsoft NL DB toolkit
Information Retrieval (IR) [find and display relevant
information containers]
Document retrieval
Web search
Why this is not just simple document retrieval: Google
Text segmentation
Information Extraction (IE) [manipulate information into canonical forms]
Text Summarization
Find the most important paragraphs or
sentences
Try to generate an abstract
Interacts with translation: Do this in funny languages!
Get help from the world! Marti Hearst: Find papers citing this paper. The text around the citation will
often be a summary. Works best in science papers.
Document database query
Doc DB: Find the query-relevant paragraph or
cluster of sentences (Litigation support)
Online help system query
Command-oriented Systems
Online desktop
Text editor
Unix shell
Robot [SRI's Flakey, with speech interface]
Simulated armed forces (user=commander)
Kitchen appliances
Dialog Systems
Intelligent Tutors (Language, Reading, Math, etc. )
Student Modeling
Behavior, skill, and preference modeling
Error analysis
Translation Systems
MT systems: Not
very good, not very widely used, except perhaps on the Web ("Translate this page" button. Type
"Poisson frit" to Google; Type "ryba smazona" to Google The translation, The original)
Translator's assistant:
a resource for a human translator
Theoretical Applications
Theory-specification tool
Zellig-Harris Transformational Grammar and the Linguistic
String Project (Transformational and Discourse Analysis Project, Sager, NYU String Grammar project)
Chomskyan Transformational Grammars and ATNs (Woods, Moonrock
system)
Lexical Functional Grammar (LFG, Ron Kaplan, Xerox PARC
system)
Generalized Phrase Structure Grammar (GPSG, HP system)
Head-Driven Phrase Structure Grammar (HPSG, HP system,
Verbmobil English grammar at Stanford)
Theoretical modeling
Processing models
Syntax
Garden path models (Bever 1970, McDonald 1993 and Jurafsky 1996)
The horse raced past the barn fell.
The complex houses married and single students
and their families.
The student forgot the solution was in the back
of the book.
Parse preference models (attachment preferences modeled;
Pereira 1985, models "minimal attachment" and
"right association" of Kimball 1973)
"Shallow" parsing (finite-state) models of human processing
(Church 1980, Ramshaw and Marcus 1995, Argammom, et al. 1998,
Munoz et al. 1999, Chapter 10, our text)
Semantics
The astronomer married the star.
The movie director married a star.(Reder 1983, Uszkoreit 1990)
Speech recognition systems as crude phonological processing
models
Language Acquisition models
Unsupervised learning systems
Segmentation (Michael Brent)
Derivational Morphology (Watkinson and Manandhar)
PDP models
Language change models (simulation)
Briscoe 2000: biased learning creates linguistic change
History
Foundational insights (40s and 50s)
McCulloch-Pitts neuron: a simplified computational
model of a neuron
Shannon (1948): automata for language, incorporating
probablistic models
Chomsky (1956): formal language theory
Sound spectrograph (Koenig et al. 1946): foundation for
instrumental phonetics.
First machine speech recognizers (Bell Labs, Davis et al. 1952)
Shannon-Weaver information theory: Noisy channel model
Two camps (57-70)
AI
Beginnings of Artifical Intelligence as a field (John
McCarthy, Marvin Minsky, Clause Shannon, Nathaniel Rochester)
Newell and Simon Logic Theorist and Problem Solver. computable
models of reasoning and logic
Subjects speak aloud as they solve problems
Problem solving modeled with a production-system
where the productions (or reasoning steps) correspond to
the steps human reasoners took for those kinds
of problems.
George Miller and Donald Broadbent: importing computational ideas
into psychology.
Bayesian method and optical character recognition: Using
probabilistic methods on recognition problems (see Chapter 5, history
section, our text)
Zellig Harris project (mentioned above)
Brown Corpus
Four paradigms (70-83)
Stochastic: HMMs in speech recognition (Jelinek, Bahl and Mercer at IBM)
Logic-based programming Prolog:
Q-systems aand metamorphosis grammars (Colmerauer)
Prolog, Definite Clause Grammars (Pereira and Warren 1980)
Unification grammar (Kay, Bresnan and Kaplan)
Natural language understanding(Winograd, serious attention
to semantics)
Winograd SHRDLU, blocks world
Yale school: Scripts, plans, goals (Schank and Abelson,
Wilensky, Lehnert). Story and text understanding.
Discourse-modeling (Grosz, Sidner, Perrault, Allen, Cohen).
Discourse as plans guided by intentions and beliefs.
Communicative acts as steps in plans.
Empiricism and Finite-state models redux (83-99)
Finite-state models
phonology and morphology (Kaplan and Kay 1981, Koskenniemi, Karttunen)
syntax (Church 1980)
Probabilistic models
Speech recognition work at IBM
Part of speech tagging (history section, chapter 8)
utter, direct: adj, v
walk, pilot, sneer, help: N,V
hard: adj, adv
Probabilistic parsing (history section, chapter 12)
The field comes together (94-99)
Spread of probabilistic methods to all kinds of problems
Commercial ventures using speech, some NLP
The web
Some lessened emphasis on theoretical work
Reasons for the expansion of Computational Linguistics in recent years
Success of Speech recognition
Increase in computing power and storage capacity of machines
Availability of online text and speech resources in
unprecedented quantities
Success of statistical methods
World-wide web (applications and data)
Increasing demand for translation
Globalization of information, standards, software
Availability of venture capital
(no longer so true!)
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