Lecture 22: NLP for IR

2010.04.21 - SLIDE 1IS 240 – Spring 2010

Prof. Ray Larson University of California, Berkeley

School of Information

Principles of Information Retrieval

Lecture 22: NLP for IR

2010.04.21 - SLIDE 2IS 240 – Spring 2010

Today • MiniTREC results• Review

– Cheshire III Design – GRID-based DLs• NLP for IR• Text Summarization

Credit for some of the slides in this lecture goes to Marti Hearst and Eric Brewer

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MiniTREC 2010-All Submissions

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MiniTREC 2010 - Best Runs

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Grid

mid

dlew

are

Che m

ical

Eng i

nee r

ing

Applications

ApplicationToolkits

GridServices

GridFabric

Clim

ate

Data

Grid

Rem

ote

Com

putin

g

Rem

ote

Visu

aliza

tion

Colla

bora

torie

s

High

ene

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phy

sics

Cosm

olog

y

Astro

phys

ics

Com

bust

ion

.….

Porta

ls

Rem

ote

sens

ors

..…Protocols, authentication, policy, instrumentation,Resource management, discovery, events, etc.

Storage, networks, computers, display devices, etc.and their associated local services

Grid Architecture -- (Dr. Eric Yen, Academia Sinica, Taiwan.)

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Che m

ical

Eng i

nee r

ing

Applications

ApplicationToolkits

GridServices

GridFabric

Grid

mid

dlew

are

Clim

ate

Data

Grid

Rem

ote

Com

putin

g

Rem

ote

Visu

aliza

tion

Colla

bora

torie

s

High

ene

rgy

phy

sics

Cosm

olog

y

Astro

phys

ics

Com

bust

ion

Hum

anitie

sco

mpu

ting

Digi

tal

Libr

arie

s

…

Porta

ls

Rem

ote

sens

ors

Text

Min

ing

Met

adat

am

anag

emen

t

Sear

ch &

Retri

eval …

Protocols, authentication, policy, instrumentation,Resource management, discovery, events, etc.

Storage, networks, computers, display devices, etc.and their associated local services

Grid Architecture (ECAI/AS Grid Digital Library Workshop)

Bio-

Med

ical

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Grid IR Issues• Want to preserve the same retrieval

performance (precision/recall) while hopefully increasing efficiency (I.e. speed)

• Very large-scale distribution of resources is a challenge for sub-second retrieval

• Different from most other typical Grid processes, IR is potentially less computing intensive and more data intensive

• In many ways Grid IR replicates the process (and problems) of metasearch or distributed search

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ContextData Grid

Layer

Data Grid

SRBiRODS

Digital Library LayerApplicationLayer

Web BrowserMultivalent

Dedicated Client

User Interface

Apache+Mod_Python+

Cheshire3

Protocol Handler

Process Management

KeplerCheshire3

Query Results

Query

Results

Export Parse

Document ParsersMultivalent,...

NaturalLanguageProcessing

InformationExtraction

Text Mining ToolsTsujii Labs, ...

ClassificationClustering

Data Mining ToolsOrange, Weka, ...

Query

Results

Search /Retrieve

Index /Store

Information SystemCheshire3

User Interface

MySRBPAWN

Process Management

KepleriRODS rules

Term Management

TermineWordNet

...

Store

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Grid ArchitectureMaster Task

Slave Task 1 Slave Task N

Data Grid

GPFS Temporary Storage

(workflow, process, document) (workflow, process, document)

fetch document fetch document

document document

extracted data extracted data

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Grid Architecture - Phase 2Master Task

Slave Task 1 Slave Task N

Data Grid

GPFS Temporary Storage

(index, load) (index, load)

store index store index

fetch extracted data fetch extracted data

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Today• Natural Language Processing and IR

– Based on Papers in Reader and on• David Lewis & Karen Sparck Jones “Natural

Language Processing for Information Retrieval” Communications of the ACM, 39(1) Jan. 1996

• Text summarization: Lecture from Ed Hovy (USC)

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Natural Language Processing and IR

• The main approach in applying NLP to IR has been to attempt to address– Phrase usage vs individual terms– Search expansion using related

terms/concepts– Attempts to automatically exploit or assign

controlled vocabularies

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NLP and IR• Much early research showed that (at least in the

restricted test databases tested)– Indexing documents by individual terms

corresponding to words and word stems produces retrieval results at least as good as when indexes use controlled vocabularies (whether applied manually or automatically)

– Constructing phrases or “pre-coordinated” terms provides only marginal and inconsistent improvements

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NLP and IR• Not clear why intuitively plausible

improvements to document representation have had little effect on retrieval results when compared to statistical methods– E.g. Use of syntactic role relations between

terms has shown no improvement in performance over “bag of words” approaches

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General Framework of NLP

Slides from Prof. J. Tsujii, Univ of Tokyo and Univ of Manchester

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Morphological andLexical Processing

Syntactic Analysis

Semantic Analysis

Context processingInterpretation

John runs.


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Syntactic Analysis

Semantic Analysis


John runs.

John run+s. P-N V 3-pre N plu


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Syntactic Analysis

Semantic Analysis


John runs.


S

NP

P-N

John

VP

V

run


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Syntactic Analysis

Semantic Analysis


John runs.


S

NP

P-N

John

VP

V

runPred: RUN Agent:John


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Syntactic Analysis

Semantic Analysis


John runs.


S

NP

P-N

John

VP

V

runPred: RUN Agent:John

John is a student.He runs.


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Syntactic Analysis

Semantic Analysis


Domain AnalysisAppelt:1999

Tokenization

Part of Speech Tagging

Term recognition(Ananiadou)

Inflection/DerivationCompounding


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP

(1) Robustness: Incomplete Knowledge


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP

(1) Robustness: Incomplete Knowledge Incomplete Lexicons

Open class words TermsTerm recognitionNamed Entities Company names Locations Numerical expressions


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP


Incomplete Grammar Syntactic Coverage Domain Specific Constructions Ungrammatical Constructions


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Syntactic Analysis



Semantic Analysis


Difficulties of NLP


Incomplete Domain Knowledge Interpretation Rules

PredefinedAspects of

Information


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP


(2) Ambiguities:Combinatorial

Explosion


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP



Explosion

Most words in Englishare ambiguous in terms of their parts of speech. runs: v/3pre, n/plu clubs: v/3pre, n/plu and two meanings


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP



Explosion

Structural Ambiguities

Predicate-argument Ambiguities


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(1)Attachment Ambiguities John bought a car with large seats. John bought a car with $3000.

(2) Scope Ambiguities

young women and men in the room

(3)Analytical Ambiguities Visiting relatives can be boring.

The manager of Yaxing Benz, a Sino-German joint ventureThe manager of Yaxing Benz, Mr. John Smith

John bought a car with Mary.$3000 can buy a nice car.

Semantic Ambiguities(1)

Semantic Ambiguities(2)

Every man loves a woman.

Co-reference Ambiguities


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Syntactic Analysis

Semantic Analysis


Difficulties of NLP



Explosion


Predicate-argument Ambiguities

CombinatorialExplosion


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Note:

Ambiguities vs Robustness

More comprehensive knowledge: More Robust

big dictionariescomprehensive grammar

More comprehensive knowledge: More ambiguities

Adaptability: Tuning, LearningSlides from Prof. J. Tsujii, Univ of Tokyo and Univ of Manchester

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Framework of IE

IE as compromise NLP


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Syntactic Analysis



Semantic Analysis


Difficulties of NLP




Information


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Syntactic Analysis



Semantic Analysis


Difficulties of NLP




Information


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Techniques in IE

(1) Domain Specific Partial Knowledge: Knowledge relevant to information to be extracted(2) Ambiguities: Ignoring irrelevant ambiguities Simpler NLP techniques

(4) Adaptation Techniques: Machine Learning, Trainable systems

(3) Robustness: Coping with Incomplete dictionaries (open class words) Ignoring irrelevant parts of sentences


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Syntactic Analysis

Semantic Anaysis


Open class words: Named entity recognition (ex) Locations Persons Companies Organizations Position names

Domain specific rules: <Word><Word>, Inc. Mr. <Cpt-L>. <Word>Machine Learning: HMM, Decision TreesRules + Machine Learning

Part of Speech Tagger FSA rulesStatistic taggers

95 %

F-Value90

DomainDependent

Local ContextStatistical Bias


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Syntactic Analysis

Semantic Anaysis


FASTUS

1.Complex Words: Recognition of multi-words and proper names

2.Basic Phrases:Simple noun groups, verb groups and particles

3.Complex phrases:Complex noun groups and verb groups

4.Domain Events:Patterns for events of interest to the applicationBasic templates are to be built.

5. Merging Structures:Templates from different parts of the texts are merged if they provide information about the same entity or event.

Based on finite states automata (FSA)


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Syntactic Analysis

Semantic Anaysis


FASTUS








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Syntactic Analysis

Semantic Analysis


FASTUS








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Using NLP• Strzalkowski (in Reader)

Text NLP repres Dbasesearch

TAGGERNLP: PARSER TERMS

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Using NLP

INPUT SENTENCEThe former Soviet President has been a local hero ever sincea Russian tank invaded Wisconsin.

TAGGED SENTENCEThe/dt former/jj Soviet/jj President/nn has/vbz been/vbn a/dt local/jj hero/nn ever/rb since/in a/dt Russian/jj tank/nn invaded/vbd Wisconsin/np ./per

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Using NLP

TAGGED & STEMMED SENTENCEthe/dt former/jj soviet/jj president/nn have/vbz be/vbn a/dt local/jj hero/nn ever/rb since/in a/dt russian/jj tank/nn invade/vbd wisconsin/np ./per

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Using NLP

PARSED SENTENCE[assert [[perf [have]][[verb[BE]] [subject [np[n PRESIDENT][t_pos THE] [adj[FORMER]][adj[SOVIET]]]] [adv EVER] [sub_ord[SINCE [[verb[INVADE]] [subject [np [n TANK][t_pos A] [adj [RUSSIAN]]]] [object [np [name [WISCONSIN]]]]]]]]]

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Using NLP

EXTRACTED TERMS & WEIGHTSPresident 2.623519 soviet 5.416102President+soviet 11.556747 president+former 14.594883Hero 7.896426 hero+local 14.314775Invade 8.435012 tank 6.848128Tank+invade 17.402237 tank+russian 16.030809Russian 7.383342 wisconsin 7.785689

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Same Sentence, different sys

INPUT SENTENCEThe former Soviet President has been a local hero ever sincea Russian tank invaded Wisconsin.

TAGGED SENTENCE (using uptagger from Tsujii)The/DT former/JJ Soviet/NNP President/NNP has/VBZ been/VBN a/DT local/JJ hero/NN ever/RB since/IN a/DT Russian/JJ tank/NN invaded/VBD Wisconsin/NNP ./.

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Same Sentence, different sys

CHUNKED Sentence (chunkparser – Tsujii)(TOP (S (NP (DT The) (JJ former) (NNP Soviet) (NNP President) ) (VP (VBZ has) (VP (VBN been) (NP (DT a) (JJ local) (NN hero) ) (ADVP (RB ever) ) (SBAR (IN since) (S (NP (DT a) (JJ Russian) (NN tank) ) (VP (VBD invaded) (NP (NNP Wisconsin) ) ) ) ) ) ) (. .) ) )

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Same Sentence, different sysEnju ParserROOT ROOT ROOT ROOT -1 ROOT been be VBN VB 5been be VBN VB 5 ARG1 President president NNP NNP 3been be VBN VB 5 ARG2 hero hero NN NN 8a a DT DT 6 ARG1 hero hero NN NN 8a a DT DT 11 ARG1 tank tank NN NN 13local local JJ JJ 7 ARG1 hero hero NN NN 8The the DT DT 0 ARG1 President president NNP NNP 3former former JJ JJ 1 ARG1 President president NNP NNP 3Russian russian JJ JJ 12 ARG1 tank tank NN NN 13Soviet soviet NNP NNP 2 MOD President president NNP NNP 3invaded invade VBD VB 14 ARG1 tank tank NN NN 13invaded invade VBD VB 14 ARG2 Wisconsin wisconsin NNP NNP 15has have VBZ VB 4 ARG1 President president NNP NNP 3has have VBZ VB 4 ARG2 been be VBN VB 5since since IN IN 10 MOD been be VBN VB 5since since IN IN 10 ARG1 invaded invade VBD VB 14ever ever RB RB 9 ARG1 since since IN IN 10

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NLP & IR• Indexing

– Use of NLP methods to identify phrases• Test weighting schemes for phrases

– Use of more sophisticated morphological analysis

• Searching– Use of two-stage retrieval

• Statistical retrieval• Followed by more sophisticated NLP filtering

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NPL & IR• Lewis and Sparck Jones suggest research in

three areas– Examination of the words, phrases and sentences

that make up a document description and express the combinatory, syntagmatic relations between single terms

– The classificatory structure over document collection as a whole, indicating the paradigmatic relations between terms and permitting controlled vocabulary indexing and searching

– Using NLP-based methods for searching and matching

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NLP & IR Issues• Is natural language indexing using more

NLP knowledge needed?• Or, should controlled vocabularies be used• Can NLP in its current state provide the

improvements needed• How to test

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NLP & IR• New “Question Answering” track at TREC

has been exploring these areas– Usually statistical methods are used to

retrieve candidate documents– NLP techniques are used to extract the likely

answers from the text of the documents

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Mark’s idle speculation• What people think is going on always

Keywords

NLPFrom Mark Sanderson, University of Sheffield

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Mark’s idle speculation• What’s usually actually going on

KeywordsNLPFrom Mark Sanderson, University of Sheffield

Documents

Lecture 22: NLP for IR