What is WordnetWhat is WordnetCoimbatore WorkshopCoimbatore Workshop

atatAmrita UniversityAmrita University

Pushpak BhattacharyyaPushpak Bhattacharyya

CSE Dept., CSE Dept., IIT Bombay IIT Bombay

WordnetWordnet

• A lexical knowledgebase based on A lexical knowledgebase based on conceptual lookupconceptual lookup

• Organizing concepts in a semantic Organizing concepts in a semantic network.network.

• Organize lexical information in Organize lexical information in terms of word meaning, rather terms of word meaning, rather than word formthan word form

• Wordnet can also be used as a thesaurus.Wordnet can also be used as a thesaurus.

Psycholinguistic Theory Psycholinguistic Theory • Human lexical memory for nouns as a hierarchy.Human lexical memory for nouns as a hierarchy.• Can canary sing? - Pretty fast response.Can canary sing? - Pretty fast response.• Can canary fly? - Slower response.Can canary fly? - Slower response.• Does canary have skin? – Slowest response.Does canary have skin? – Slowest response.

(can move, has skin)(can move, has skin)

(can fly) (can fly)

(can sing)(can sing)

Wordnet - a lexical reference system based on psycholinguistic Wordnet - a lexical reference system based on psycholinguistic theories of theories of human lexical memory. human lexical memory.

Animal

Bird

canary

Lexical MatrixLexical Matrix

WordnetWordnet

• Wordnet is a network of words linked by lexical Wordnet is a network of words linked by lexical and semantic relations.and semantic relations.

• The first wordnet in the world was for English The first wordnet in the world was for English developed at Princeton over 15 years.developed at Princeton over 15 years.

• The Eurowordnet- linked structure of European The Eurowordnet- linked structure of European language wordnets was built in 1998 over 3 years language wordnets was built in 1998 over 3 years with funding from the EC as a a mission mode with funding from the EC as a a mission mode project.project.

• Wordnets for Hindi and Marathi being built at IIT Wordnets for Hindi and Marathi being built at IIT Bombay are amongst the first IL wordnets.Bombay are amongst the first IL wordnets.

• All these are proposed to be linked into the All these are proposed to be linked into the IndoWordnet IndoWordnet which eventually will be linked to which eventually will be linked to the English and the Euro wordnets.the English and the Euro wordnets.

Fundamental Design Fundamental Design QuestionQuestion

• SyntagmaticSyntagmatic vs. vs. Paradigmatic Paradigmatic realtions?realtions?

• Psycholinguistics is the basis of the design.Psycholinguistics is the basis of the design.• When we hear a word, many words come When we hear a word, many words come

to our mind to our mind by associationby association..• For English, about half of the associated For English, about half of the associated

words are words are syntagmatically relatedsyntagmatically related and half and half are are paradignatically related.paradignatically related.

• For For catcat– animal, mammalanimal, mammal- paradigmatic- paradigmatic– mew, purr, furrymew, purr, furry- syntagmatic- syntagmatic

Stated Fundamental Application Stated Fundamental Application of Wordnet: of Wordnet: Sense Sense DisambiguationDisambiguation

Determination of the correct sense of Determination of the correct sense of the wordthe word

The crane ate the fish The crane ate the fish vs.vs.

The crane was used to lift the The crane was used to lift the loadload

bird bird vs. vs. machinemachine

The problem of Sense The problem of Sense taggingtagging

• Given a corpora Given a corpora To Assign correct To Assign correct sense to the words. sense to the words.

• This is sense tagging. Needs This is sense tagging. Needs Word Word Sense Disambiguation (WSD)Sense Disambiguation (WSD)

• Highly important for Question Highly important for Question Answering, Machine Translation, Answering, Machine Translation, Text Mining tasks.Text Mining tasks.

Basic PrincipleBasic Principle

• Words in natural languages are polysemous.Words in natural languages are polysemous.• However, when synonymous words are put However, when synonymous words are put

together, a unique meaning often emerges.together, a unique meaning often emerges.• Use is made of Use is made of Relational Semantics.Relational Semantics.• Componential Semantics Componential Semantics where each word is a where each word is a

bundle of semantic features bundle of semantic features (as in the (as in the Schankian Schankian Conceptual Dependency Conceptual Dependency system or system or Lexical Componential Semantics)Lexical Componential Semantics) is to be is to be examined as a viable alternative.examined as a viable alternative.

Componential SemanticsComponential Semantics

• Consider Consider cat cat and and tiger. tiger. Decide on Decide on componential componential attributes.attributes.

• For For cat cat (Y, Y, N, Y)(Y, Y, N, Y)• For For tiger tiger (Y,Y,Y,N)(Y,Y,Y,N) Complete and correct Complete and correct

Attributes are difficult Attributes are difficult to design.to design.

FurryFurry CarnivoroCarnivorousus

HeavyHeavy DomesticaDomesticableble

Semantic relations in Semantic relations in wordnetwordnet1.1. SynonymySynonymy2.2. Hypernymy / HyponymyHypernymy / Hyponymy3.3. AntonymyAntonymy4.4. Meronymy / HolonymyMeronymy / Holonymy5.5. GradationGradation6.6. Entailment Entailment 7.7. TroponymyTroponymy1, 3 and 5 are lexical (1, 3 and 5 are lexical (word to word)word to word), rest , rest

are semantic (are semantic (synset to synset).synset to synset).

Synset: the Synset: the foundationfoundation((house)house)

1. 1. househouse -- (a dwelling that serves as living quarters for one or more families; "he has a -- (a dwelling that serves as living quarters for one or more families; "he has a house on Cape Cod"; "she felt she had to get out of the house")house on Cape Cod"; "she felt she had to get out of the house")2. 2. househouse -- (an official assembly having legislative powers; "the legislature has two -- (an official assembly having legislative powers; "the legislature has two houses")houses")3. 3. househouse -- (a building in which something is sheltered or located; "they had a large -- (a building in which something is sheltered or located; "they had a large carriage house")carriage house")4. family, household, 4. family, household, househouse, home, menage -- (a social unit living together; "he moved his , home, menage -- (a social unit living together; "he moved his family to Virginia"; "It was a good Christian household"; "I waited until the whole house family to Virginia"; "It was a good Christian household"; "I waited until the whole house was asleep"; "the teacher asked how many people made up his home")was asleep"; "the teacher asked how many people made up his home")5. theater, theatre, 5. theater, theatre, househouse -- (a building where theatrical performances or motion-picture -- (a building where theatrical performances or motion-picture shows can be presented; "the house was full")shows can be presented; "the house was full")6. firm, 6. firm, househouse, business firm -- (members of a business organization that owns or , business firm -- (members of a business organization that owns or operates one or more establishments; "he worked for a brokerage house")operates one or more establishments; "he worked for a brokerage house")7. 7. househouse -- (aristocratic family line; "the House of York") -- (aristocratic family line; "the House of York")8. 8. househouse -- (the members of a religious community living together) -- (the members of a religious community living together)9. 9. househouse -- (the audience gathered together in a theatre or cinema; "the house -- (the audience gathered together in a theatre or cinema; "the house applauded"; "he counted the house")applauded"; "he counted the house")10. 10. househouse -- (play in which children take the roles of father or mother or children and -- (play in which children take the roles of father or mother or children and pretend to interact like adults; "the children were playing house")pretend to interact like adults; "the children were playing house")11. sign of the zodiac, star sign, sign, mansion, 11. sign of the zodiac, star sign, sign, mansion, househouse, planetary house -- ((astrology) one , planetary house -- ((astrology) one of 12 equal areas into which the zodiac is divided)of 12 equal areas into which the zodiac is divided)12. 12. househouse -- (the management of a gambling house or casino; "the house gets a -- (the management of a gambling house or casino; "the house gets a percentage of every bet")percentage of every bet")

Creation of SynsetsCreation of Synsets

Three principles:Three principles:•MinimalityMinimality•CoverageCoverage•ReplacabilityReplacability

Synset creation (Synset creation (continued)continued)

HomeHomeJohn’s home was decorated with lights on the occasion of John’s home was decorated with lights on the occasion of

Christmas.Christmas.Having worked for many years abroad, John Returned home.Having worked for many years abroad, John Returned home.

HouseHouseJohn’s house was decorated with lights on the occasion of John’s house was decorated with lights on the occasion of

Christmas.Christmas.Mercury is situated in the eighth house of John’s horoscope.Mercury is situated in the eighth house of John’s horoscope.

Synsets (Synsets (continued)continued)

{{househouse} is ambiguous.} is ambiguous.{{househouse,, homehome} has the sense of } has the sense of a social unit living a social unit living

together;together;Is this the minimal unit?Is this the minimal unit?{family, house , home} will make the unit completely {family, house , home} will make the unit completely

unambiguous.unambiguous.

For coverage:For coverage:{family, household, house, home} ordered according {family, household, house, home} ordered according

to frequency.to frequency.

Replacability of the most frequent words is a Replacability of the most frequent words is a requirement. requirement.

Synset creationSynset creation

From first principlesFrom first principles– Pick all the senses from good standard Pick all the senses from good standard

dictionaries.dictionaries.– Obtain synonyms for each sense.Obtain synonyms for each sense.– Needs hard and long hours of work.Needs hard and long hours of work.

Synset creation Synset creation (continued)(continued)

From the wordnet of another language in the From the wordnet of another language in the same same familyfamily– Pick the synset and obtain the sense from the Pick the synset and obtain the sense from the

gloss.gloss.– Get the words of the target language.Get the words of the target language.– Often same words can be used- especially for Often same words can be used- especially for tt

%sama %sama words.words.– Translation, Insertion and deletion.Translation, Insertion and deletion.

Hindi Synset:Hindi Synset: AnauBavaI jaanakar maMjaa huAa AnauBavaI jaanakar maMjaa huAa (experienced person)(experienced person)

Marathi Synset:Marathi Synset: AnauBavaI t& jaaNata &ataAnauBavaI t& jaaNata &ata

Gloss and ExampleGloss and Example

Crucially needed for concept explication, wordnet building using Crucially needed for concept explication, wordnet building using another wordnet and wordnet linking.another wordnet and wordnet linking.

{earthquake, {earthquake, quakequake, temblor, seism} -- (shaking and vibration at the , temblor, seism} -- (shaking and vibration at the surface of the earth resulting from underground movement along a surface of the earth resulting from underground movement along a fault plane of from volcanic activity)fault plane of from volcanic activity)

Hindi Synset:Hindi Synset: {{BaUkMpBaUkMp,, BaUcaala BaUcaala,, BaUDaola BaUDaola};}; pRqvaIko pRqvaIko pRYzBaagaka ihlanaapRYzBaagaka ihlanaa; ; gaujaratmaoM hue BaUkMpmaoM gaujaratmaoM hue BaUkMpmaoM Anaok laaoga maaro gayao. Anaok laaoga maaro gayao.

(shaking of the surface of earth; many were killed in the earthquake in (shaking of the surface of earth; many were killed in the earthquake in Gujarat)Gujarat)

Marathi Synset:Marathi Synset: { {BaUkMpBaUkMp,, QarNaIkMp QarNaIkMp};}; pRqvaIcaa pRqvaIcaa pRYzBaaga halaNyaacaI ik/yaapRYzBaaga halaNyaacaI ik/yaa;; gaujaraqamaQyao gaujaraqamaQyao Jaalaolyaa BaUkMpat Anaok laaok maarlao gaolao.Jaalaolyaa BaUkMpat Anaok laaok maarlao gaolao.

Semantic RelationsSemantic Relations

• Hypernymy and HyponymyHypernymy and Hyponymy– Relation between word senses (Relation between word senses (synsetssynsets))– X is a hyponym of Y X is a hyponym of Y if if X is a kind of YX is a kind of Y– Hyponymy is transitive and Hyponymy is transitive and

asymmetricalasymmetrical– Hypernymy is inverse of HyponymyHypernymy is inverse of Hyponymy

(lion->animal->animate entity->entity)(lion->animal->animate entity->entity)

Semantic Relations Semantic Relations (continued)(continued)

• Meronymy and HolonymyMeronymy and Holonymy– Part-whole relation, branch is a part of Part-whole relation, branch is a part of

treetree– X is a meronymy of Y X is a meronymy of Y ifif X is a part of Y X is a part of Y– Holonymy is the inverse relation of Holonymy is the inverse relation of

MeronymyMeronymy

{kitchen} ………………………. {house}{kitchen} ………………………. {house}

Lexical RelationLexical Relation

• AntonymyAntonymy– Oppositeness in meaning Oppositeness in meaning – Relation between word formsRelation between word forms– Often determined by phonetics, word Often determined by phonetics, word

length etc. ({rise, ascend} length etc. ({rise, ascend} vs. vs. {fall, {fall, descend})descend})

Troponym and EntailmentTroponym and Entailment

• EntailmentEntailment {snoring {snoring –– sleeping} sleeping}

• TroponymTroponym {limp, strut {limp, strut –– walk} walk}

{whisper {whisper –– talk} talk}

Entailment.Entailment.

Snoring entails sleeping.Snoring entails sleeping.

Buying entails paying.Buying entails paying.

• Proper Temporal Inclusion. Proper Temporal Inclusion. Inclusion can be in any way. Inclusion can be in any way.

Sleeping temporally includes snoring.Sleeping temporally includes snoring.

Buying temporally includes paying.Buying temporally includes paying.

• Co-extensiveness. (Troponymy)Co-extensiveness. (Troponymy)Limping is a manner of walking. Limping is a manner of walking.

Opposition among verbs.Opposition among verbs.

• {Rise,ascend} {fall,descend}{Rise,ascend} {fall,descend} Tie-untie (do-undo)Tie-untie (do-undo)

Walk-run (slow,fast)Walk-run (slow,fast)

Teach-learn (same activity different perspective)Teach-learn (same activity different perspective)

Rise-fall (motion upward or downward)Rise-fall (motion upward or downward)

• Opposition and Entailment.Opposition and Entailment. Hit or miss (entail aim) . Backward presupposition.Hit or miss (entail aim) . Backward presupposition.

Succeed or fail (entail try.)Succeed or fail (entail try.)

The causal relationship.The causal relationship.

Show- see.Show- see.

Give- have.Give- have.

Causation and Entailment. Causation and Entailment. Giving entails having. Giving entails having.

Feeding entails eating. Feeding entails eating.

Kinds of AntonymyKinds of AntonymySizeSize Small - BigSmall - BigQualityQuality Good Good –– Bad BadStateState Warm Warm –– Cool CoolPersonalityPersonality Dr. Jekyl- Mr. HydeDr. Jekyl- Mr. HydeDirectionDirection East- WestEast- WestActionAction Buy Buy –– Sell SellAmountAmount Little Little –– A lot A lotPlacePlace Far Far –– Near NearTimeTime Day - NightDay - NightGenderGender Boy - GirlBoy - Girl

Kinds of MeronymyKinds of Meronymy

Component-Component-objectobject

Head - BodyHead - Body

Staff-objectStaff-object Wood - TableWood - TableMember-Member-

collectioncollectionTree - ForestTree - Forest

Feature-ActivityFeature-Activity Speech - Speech - ConferenceConference

Place-AreaPlace-Area Palo Alto - Palo Alto - CaliforniaCalifornia

Phase-StatePhase-State Youth - LifeYouth - LifeResource-Resource-

processprocessPen - WritingPen - Writing

Actor-ActActor-Act Physician - Physician - TreatmentTreatment

GradationGradation

StateState Childhood, Youth, Old Childhood, Youth, Old ageage

TemperatureTemperature Hot, Warm, ColdHot, Warm, Cold

ActionAction Sleep, Doze, WakeSleep, Doze, Wake

Gloss

study

Hyponymy

Hyponymy

Dwelling,abode

bedroom

kitchen

house,home

A place that serves as the living quarters of one or mor efamilies

guestroom

veranda

bckyard

hermitage cottage

Meronymy

Hyponymy

Meronymy

Hypernymy

WordNet Sub-GraphWordNet Sub-Graph

SummarySummary

• Synsets: basic unitsSynsets: basic units

• Principles of creation: minimality, Principles of creation: minimality, coverage, replaceabilitycoverage, replaceability

• Semantic relations (main ones): Semantic relations (main ones): hypernymy (is-a), meronymy (part-hypernymy (is-a), meronymy (part-of), antomymy, troponymy (manner-of), antomymy, troponymy (manner-of)of)