The Global Wordnet Grid: anchoring languages to universal meaning

Piek Vossen

Irion Technologies/Free University of Amsterdam

and

Christiane Fellbaum

Princeton University

Overview

• Wordnet, EuroWordNet background

• Architecture of the Global Wordnet Grid

• Mapping wordnets to the Grid

• Kyoto: an implementation of the Grid

WordNet1.5WordNet1.5• Developed at Princeton by George Miller and his

team as a model of the mental lexicon.• Semantic network in which concepts are defined in

terms of relations to other concepts.• Structure:

organized around the notion of synsets (sets of synonymous words)

basic semantic relations between these synsets

http://www.cogsci.princeton.edu/~wn/w3wn.htmlhttp://www.cogsci.princeton.edu/~wn/w3wn.html

Structure of WordNet

{vehicle}

{conveyance; transport}

{car; auto; automobile; machine; motorcar}

{cruiser; squad car; patrol car; police car; prowl car} {cab; taxi; hack; taxicab; }

{motor vehicle; automotive vehicle}

{bumper}

{car door}

{car window}

{car mirror}

{hinge; flexible joint}

{doorlock}

{armrest}

hyperonym

hyperonym

hyperonym

hyperonymhyperonym

meronym

meronym

meronym

meronym

EuroWordNet

• The development of a multilingual database with wordnets for several European languages

• Funded by the European Commission, DG XIII, Luxembourg as projects LE2-4003 and LE4-8328

• March 1996 - September 1999

• 2.5 Million EURO.

• http://www.hum.uva.nl/~ewn

• http://www.illc.uva.nl/EuroWordNet/finalresults-ewn.html

ENGLISHCar…

Train…

Vehicle

Inter-Lingual-Index

Transport

Road Air Water

Domains Top Ontology

Device

Object

TransportDevice

English Words

vehicle

car train

1

2

4

3 3

Czech Words

dopravní prostředník

auto vlak

2

1French Words

véhicule

voiture train

2

1

Estonian Words

liiklusvahend

auto killavoor

2

1

German Words

Fahrzeug

Auto Zug

2

1

Spanish Words

vehículo

auto tren

2

1

Italian Words

veicolo

auto treno

2

1

Dutch Words

voertuig

auto trein

2

1

EuroWordnet architecture

EuroWordNet

• Wordnets are unique language-specific structures:– different lexicalizations– differences in synonymy and homonymy– different relations between synsets– same organizational principles: synset structure and

same set of semantic relations.

• Language independent knowledge is assigned to the ILI and can thus be shared for all language linked to the ILI: both an ontology and domain hierarchy

Autonomous & Language-Specific

voorwerp{object}

lepel{spoon}

werktuig{tool}

tas{bag}

bak{box}

blok{block}

lichaam{body}

Wordnet1.5 Dutch Wordnet

bagspoonbox

object

natural object (an object occurring naturally)

artifact, artefact (a man-made object)

instrumentality block body

containerdeviceimplement

tool instrument

Artificial ontology: • better control or performance, or a more compact and coherent structure. • introduce artificial levels for concepts which are not lexicalized in a language (e.g. instrumentality, hand tool), • neglect levels which are lexicalized but not relevant for the purpose of the ontology (e.g. tableware, silverware, merchandise).

What properties can we infer for spoons?spoon -> container; artifact; hand tool; object; made of metal or plastic; for eating, pouring or cooking

Linguistic versus Artificial Ontologies

Linguistic ontology: • Exactly reflects the relations between all the lexicalized words and

expressions in a language. • Captures valuable information about the lexical capacity of

languages: what is the available fund of words and expressions in a language.

What words can be used to name spoons?spoon -> object, tableware, silverware, merchandise, cutlery,

Linguistic versus Artificial Ontologies

Wordnets versus ontologies

• Wordnets:• autonomous language-specific lexicalization

patterns in a relational network. • Usage: to predict substitution in text for

information retrieval,• text generation, machine translation, word-

sense-disambiguation.• Ontologies:

• data structure with formally defined concepts.• Usage: making semantic inferences.

• Inter-Lingual-Index: unstructured fund of concepts to

provide an efficient mapping across the languages;

• Index-records are mainly based on WordNet synsets and

consist of synonyms, glosses and source references;

• Various types of complex equivalence relations are

distinguished;

• Equivalence relations from synsets to index records: not on a

word-to-word basis;

• Indirect matching of synsets linked to the same index items;

The Multilingual DesignThe Multilingual Design

Equivalent Near SynonymEquivalent Near Synonym1. Multiple Targets (1:many)

Dutch wordnet: schoonmaken (to clean) matches with 4 senses of clean in WordNet1.5:• make clean by removing dirt, filth, or unwanted substances from• remove unwanted substances from, such as feathers or pits, as of chickens or fruit• remove in making clean; "Clean the spots off the rug"• remove unwanted substances from - (as in chemistry)

2. Multiple Sources (many:1)Dutch wordnet: versiersel near_synonym versiering ILI-Record: decoration.

3. Multiple Targets and Sources (many:many)Dutch wordnet: toestel near_synonym apparaat

ILI-records: machine; device; apparatus; tool

Equivalent HyperonymyTypically used for gaps in English WordNet:

• genuine, cultural gaps for things not known in English culture:

– Dutch: klunen, to walk on skates over land from one frozen water to the other

– Dutch: citroenjenever, which is a kind of gin made out of lemon skin,

• pragmatic, in the sense that the concept is known but is not expressed by a single lexicalized form in English:

– Dutch: kunstproduct = artifact substance <=> artifact object– Dutch: hoofd = human head and Dutch: kop = animal head, English

uses head for both.

From EuroWordNet to Global WordNet

• Currently, wordnets exist for more than 40 languages, including:

• Arabic, Bantu, Basque, Chinese, Bulgarian, Estonian, Hebrew, Icelandic, Japanese, Kannada, Korean, Latvian, Nepali, Persian, Romanian, Sanskrit, Tamil, Thai, Turkish, Zulu...

• Many languages are genetically and typologically unrelated

• http://www.globalwordnet.org

Some downsides

• Construction is not done uniformly• Coverage differs• Not all wordnets can communicate with one

another• Proprietary rights restrict free access and usage• A lot of semantics is duplicated• Complex and obscure equivalence relations due to

linguistic differences between English and other languages

Inter-LingualOntology

Device

Object

TransportDeviceEnglish Words

vehicle

car train

1

2

3 3

Czech Words

dopravní prostředník

auto vlak

2

1French Words

véhicule

voiture train

2

1

Estonian Words

liiklusvahend

auto killavoor

2

1

German Words

Fahrzeug

Auto Zug

2

1

Spanish Words

vehículo

auto tren

2

1

Italian Words

veicolo

auto treno

2

1

Dutch Words

voertuig

auto trein

2

1

Next step: Global WordNet Grid

GWNG: Main Features

• Construct separate wordnets for each Grid language

• Contributors from each language encode the same core set of concepts plus culture/language-specific ones

• Synsets (concepts) can be mapped crosslinguistically via an ontology

• No license constraints, freely available

The Ontology: Main Features

• Formal, artificial ontology serves as universal index of concepts

• List of concepts is not just based on the lexicon of a particular language (unlike in EuroWordNet) but uses ontological observations

• Concepts are related in a type hierarchy• Concepts are defined with axioms

The Ontology: Main Features

• In addition to high-level (“primitive”) concept ontology needs to express low-level concepts lexicalized in the Grid languages

• Additional concepts can be defined with expressions in Knowledge Interchange Format (KIF) based on first order predicate calculus and atomic element

The Ontology: Main Features

• Minimal set of concepts (Reductionist view):

– to express equivalence across languages– to support inferencing

• Ontology must be powerful enough to encode all concepts that are lexically expressed in any of the Grid languages

The Ontology: Main Features

• Ontology need not and cannot provide a linguistic encoding for all concepts found in the Grid languages – Lexicalization in a language is not sufficient to warrant

inclusion in the ontology– Lexicalization in all or many languages may be

sufficient• Ontological observations will be used to define the

concepts in the ontology

Ontological observations• Identity criteria as used in OntoClean (Guarino &

Welty 2002), :– rigidity: to what extent are properties true for entities

in all worlds? You are always a human, but you can be a student for a short while.

– essence: what properties are essential for an entity? Shape is essential for a statue but not for the clay it is made of.

– unicity: what represents a whole and what entities are parts of these wholes? An ocean is a whole but the water it contains is not.

Type-role distinction

• Current WordNet treatment:(1) a husky is a kind of dog(type)(2) a husky is a kind of working dog (role)

• What’s wrong? (2) is defeasible, (1) is not:*This husky is not a dogThis husky is not a working dog

Other roles: watchdog, sheepdog, herding dog, lapdog, etc….

Ontology and lexicon

•Hierarchy of disjunct types:Canine PoodleDog; NewfoundlandDog;

GermanShepherdDog; Husky

•Lexicon:– NAMES for TYPES:

{poodle}EN, {poedel}NL, {pudoru}JP((instance x Poodle)

– LABELS for ROLES:{watchdog}EN, {waakhond}NL, {banken}JP

((instance x Canine) and (role x GuardingProcess))

Ontology and lexicon

•Hierarchy of disjunct types:River; Clay; etc…

•Lexicon:– NAMES for TYPES:

{river}EN, {rivier, stroom}NL((instance x River)

– LABELS for dependent concepts:{rivierwater}NL (water from a river => water is not Unit)((instance x water) and (instance y River) and (portion x y){kleibrok}NL (irregularly shared piece of clay=>Non-essential) ((instance x Object) and (instance y Clay) and (portion x y)

and (shape X Irregular))

Rigidity

• The “primitive” concepts represented in the ontology are rigid types

• Entities with non-rigid properties will be represented with KIF statements

• But: ontology may include some universal, core concepts referring to roles like father, mother

Properties of the Ontology

• Minimal: terms are distinguished by essential properties only

• Comprehensive: includes all distinct concepts types of all Grid languages

• Allows definitions via KIF of all lexemes that express non-rigid, non-essential properties of types

• Logically valid, allows inferencing

Mapping Grid Languages onto the Ontology

• Explicit and precise equivalence relations among synsets in different languages, which is somehow easier:– type hierarchy is minimal– subtle differences can be encoded in KIF expressions

• Grid database contains wordnets with synsets that label – either “primitive” types in the hierarchies, – or words relating to these types in ways made explicit in KIF

expressions

• If 2 lgs. create the same KIF expression, this is a statement of equivalence!

How to construct the GWNG

• Take an existing ontology as starting point;

• Use English WordNet to maximize the number of disjunct types in the ontology;

• Link English WordNet synsets as names to the disjunct types;

• Provide KIF expressions for all other English words and synsets

How to construct the GWNG

• Copy the relation from the English Wordnet to the ontology to other languages, including KIF statements built for English

• Revise KIF statements to make the mapping more precise

• Map all words and synsets that are and cannot be mapped to English WordNet to the ontology:– propose extensions to the type hierarchy

– create KIF expressions for all non-rigid concepts

Initial Ontology: SUMO (Niles and Pease)

SUMO = Suggested Upper Merged Ontology

--consistent with good ontological practice

--fully mapped to WordNet(s): 1000 equivalence mappings, the rest through subsumption

--freely and publicly available

--allows data interoperability

--allows NLP

--allows reasoning/inferencing

Mapping Grid languages onto the Ontology

• Check existing SUMO mappings to Princeton WordNet -> extend the ontology with rigid types for specific concepts

• Extend it to many other WordNet synsets• Observe OntoClean principles! (Synsets

referring to non-rigid, non-essential, non-unicitous concepts must be expressed in KIF)

Lexicalizations not mapped to WordNet

• Not added to the type hierarchy:{straathond}NL (a dog that lives in the streets)((instance x Canine) and (habitat x Street))

• Added to the type hierarchy:{klunen}NL (to walk on skates from one frozen body to

the next over land)KluunProcess => WalkProcessAxioms:(and (instance x Human) (instance y Walk) (instance z

Skates) (wear x z) (instance s1 Skate) (instance s2 Skate) (before s1 y) (before y s2) etc…

• National dishes, customs, games,....

Most mismatching concepts are not new types

• Refer to sets of types in specific circumstances or to concept that are dependent on these types, next to {rivierwater}NL there are many others:

{theewater}NL (water used for making tea)

{koffiewater}NL (water used for making coffee)

{bluswater}NL (water used for making extinguishing file)

• Relate to linguistic phenomena:– gender, perspective, aspect, diminutives, politeness,

pejoratives, part-of-speech constraints

• {teacher}EN((instance x Human) and (agent x

TeachingProcess))

• {Lehrer}DE ((instance x Man) and (agent x TeachingProcess))

• {Lehrerin}DE ((instance x Woman) and (agent x TeachingProcess))

KIF expression for gender marking

KIF expression for perspective

sell: subj(x), direct obj(z),indirect obj(y) versus buy: subj(y), direct obj(z),indirect obj(x) (and (instance x Human)(instance y Human)

(instance z Entity) (instance e FinancialTransaction) (source x e) (destination y e) (patient e)

The same process but a different perspective by subject and object realization: marry in Russian two verbs, apprendre in French can mean teach and learn

Part-of-speech mismatches

• {bankdrukken-V}NL vs.{bench press-N}EN

• {gehuil-N}NL vs. {cry-V}EN

• {afsluiting-N}NL vs. {close-V}EN

• Process in the ontology is neutral with respect to POS!

Parallel Noun and Verb hierarchy

• event– act

• deed– sail

– promise

– change• movement

– change of location

• to happen– to act

• to do– to sell

– a promise

– to change• to move

– to move position

Encoded once as a Process in the ontology!

Mixed Noun and Adjective hierarchy

• Colour: red, blue, green, etc.

• Height: high, low

• Size: big, small

• Emotion: sad, angry, happy, anxious

• etc.Encoded once as a attributes in the ontology!

Aspectual variants

• Slavic languages: two members of a verb pair for an ongoing event and a completed event.

• English: can mark perfectivity with particles, as in the phrasal verbs eat up and read through.

• Romance languages: mark aspect by verb conjugations on the same verb.

• Dutch, verbs with marked aspect can be created by prefixing a verb with door: doorademen, dooreten, doorfietsen, doorlezen, doorpraten (continue to breathe/eat/bike/read/talk).

• These verbs are restrictions on phases of the same process• Which does NOT warrant the extension of the ontology

with separate processes for each aspectual variant

Aspectual lexicalization• Regular compositional verb structures:

doorademen: (lit. through+breath, continue to breath)

doorbetalen: (lit. through+pay, continue to pay)

doorlopen: (lit. through+walk, continue to walk)

doorfietsen: (lit. through+walk, continue to walk)

doorrijden: (lit. through+walk, continue to walk)

(and (instance x BreathProcess)(instance y Time) (instance z Time) (end x z) (expected (end x y) (after z y))

• MORE GENERAL VERBS:openmaken: (lit. open+make, to cause to be open);dichtmaken: (lit. close+make, to cause to be open);

• MORE SPECIFIC VERBS:openknijpen (lit. open+squeeze, to open by squeezing)

has_hyperonym knijpen (squeeze) & openmaken (to open)

opendraaien (lit. open+turn, to open by turning)has_hyperonym draaien (to turn) & openmaken (to open)

dichtknijpen: (lit. closed+squeeze, to close by squeezing)has_hyperonym knijpen (squeeze) & dichtmaken (to close)

dichtdraaien: (lit. closed +turn, to close by turning)has_hyperonym draaien (to turn) & dichtmaken (to close)

Lexicalization of Resultatives

Kinship relations in Arabic

• (~Eam)َع&م father's brother, paternal uncle.

• (xaAl) َخ&ال mother's brother, maternal uncle.

• (Eam~ap) َع&َّم,ة father's sister, paternal aunt.

• اَل&ة (xaAlap) َخ& mother's sister, maternal aunt

Kinship relations in Arabic

• .........• َق1يَق&ة sister, sister on the paternal (aqiyqapfull$) َش&

and maternal side (as distinct from 5َخ4ت :(uxot<) ُأ'sister' which may refer to a 'sister' from paternal or maternal side, or both sides).

• &ْك4الن (vakolAna) َث father bereaved of a child (as opposed to 1يم &ِت 1يَّم&ة or (yatiym) َي &ِت for (yatiymap) َيfeminine: 'orphan' a person whose father or mother died or both father and mother died).

• 4َل&ى &ْك (vakolaYa) َث other bereaved of a child (as opposed to 1يم &ِت 1يَّم&ة or َي &ِت for feminine: 'orphan' a َيperson whose father or mother died or both father and mother died).

father's brother, paternal uncle

WORDNETpaternal uncle => uncle

=> brother of ....????

ONTOLOGY(=> (paternalUncle ?P ?UNC) (exists (?F) (and (father ?P ?F) (brother ?F ?UNC))))

Complex Kinship concepts

Fine tune equivalence relations

• {rivier}NL (and (instance x River) (instance y RiverMouth) (instance z Country) (part y x) (location y z)

• {stroom}NL (and (instance x River) (instance y RiverMouth) (instance p RiverPart) (not (equal p y) (instance z Country) (location p z) (not (location y z))

Universality as evidence• If lexicalization of the specific process is more universal it

can be seen as evidence that the specific processes should be listed in the ontology and not the generic verb:

– English verb cut abstracts from the precise process but there are

troponyms that implicate the manner :snip, clip imply scissors, chop and hack a large knife or an axe

– Dutch there is no general verb but only specific verbs:knippen “clip, snip, cut with scissors or a scissor-like tool'”, snijden “cut with a knife or knife-like tool”, hakken “chop, hack, to cut with an axe, or similar tool”).

• If Father is lexicalized in most languages we add it to the ontology even when it is NOT Rigid!

Universality as evidence

• Artifact substance is lexicalized in Dutch and other languages => ArtifactObject in SUMO needs to be generalized to Artifact so that it can be applied to both substances and objects

Open Questions/Challenges

• What is a word, i.e., a lexical unit?• What is the status of complex lexemes like

English lightning rod, word of mouth, find out, kick the bucket?

• What is the status of compounds in Germanic languages and Chinese?– "hottentottententententoonstelling"(exposition of tents of the "hottentotten" (African tribe))

• What is a semantic unit, i.e. a concept?

Open Questions/Challenges

• Is there a core inventory of concepts that are universally encoded?

• If so, what are these concepts?• How can crosslinguistic equivalence be verified?• Is there systematicity to the language-specific

extensions?• What are the lexicalization patterns of individual

languages? • Are lexical gaps accidental or systematic?

Coverage: what belongs in a universal lexical database?

• Formal, linguistic criteria for inclusion

• Informal, cultural criteria

• Both are difficult to define and apply!

Concrete goals for GWG

• Global Wordnet Association website:

http://www.globalwordnet.org/gwa/gwa_grid.htm• 5000 Base Concepts or more:

– English

– Spanish

– Catalan

– Czech, Polish, Dutch, other wordnets

• 7th Frame Work project Kyoto

KYOTO Project• 7th Frame Work project (under negotiation)• Kowledge Yielding Ontologies for Transition-based

Organisations• Goal:

– Global Wordnet Grid = ontology + wordnets– AutoCons = Automatic concept extractors– Kybots = Knowledge yielding robots– Wiki environment for encoding domain knowledge in expert

groups– Index and retrieval software for deep semantic search

• Languages: Dutch, English, Spanish, Basque, Italian, Chinese and Japanese

• Domain of application: environmental organisations• Period: March/April 2008 - 2011

KYOTO ConsortiumUniversities• Vrije Universiteit Amterdam, Amsterdam, Netherlands• Consiglio Nazionale delle Ricerche, Pisa, Italy• Berlin-Brandenburg Academy of Sciences and Humantities, Berlin,

Germany• Euskal Herriko Unibertsitatea, San Sebastian, Spain• Academia Sinica, Taipei, Taiwan• National Institute of Information and Communications Technology,

Kyoto, Japan• Masaryk University, Brno, CzechCompanies• Irion Technologies, Delft, Netherlands• Synthema, Pisa, ItalyUsers• European Centre for Nature Conservation, Tilburg, Netherlands• World Wide Fund for Nature, Zeist, Netherlands

Environmental organizations

Capture

Index

Docs

URLs

Experts

Images

Search

Dialogue

ConceptMining

FactMining

Abstract PhysicalTop

Middle

Domain

water CO2

Substance

CO2 emission

water pollution

Universal Ontology Wordnets

Environmental organizations

CitizensGovernorsCompanies

DomainWiki

Process

Text & Meta datain XMLFormat

termhierarchy

wordnet

ConceptMiners

termrelations

ontology

Kybots

ManualRevision

WikiDEB

Client

2

3

5

domainwordnet

domainontology

Indexing

sourcedata

Capture

Data & Factsin XML Format

DEBServer

Accessend-users

Index

6

Userscenarios

Userscenarios

ManualTest

Benchmarkdata

Benchmarking

1

1

4

7 8

Abstract Physical

water CO2

Substance

CO2 emission

water pollution

Ontology Wordnets

Generic

Process

Chemical Reaction

Logical Expressions Linguistic Minersor Kybots

Domain

words words

words words

END