A Multilingual Semantic Wiki based on Attempto Controlled English and Grammatical Framework

A Multilingual Semantic Wiki based onAttempto Controlled English and

Grammatical Framework

Tobias Kuhn

Chair of Sociology, in particular of Modeling and Simulation, ETH Zurich,Switzerland

UNISA, Pretoria (South Africa)5 June 2013

About This Talk

This talk is mainly based on the following paper:

Kaarel Kaljurand and Tobias Kuhn. A Multilingual Semantic WikiBased on Attempto Controlled English and Grammatical Framework.In Proceedings of the 10th Extended Semantic Web Conference(ESWC). 2013.

It can be downloaded here:http://purl.org/tkuhn/eswc2013acewikigf

Tobias Kuhn, ETH Zurich A Multilingual Semantic Wiki 2 / 31

http://purl.org/tkuhn/eswc2013acewikigf

Imagine ...

... that Wikipedia can check consistency andanswer questions about the contained

knowledge, and

...that all content is instantly available in alllanguages!


• AceWiki is a semantic wiki

• Articles are written in Attempto Controlled English (ACE)

• These sentences are internally translated into the Semantic Weblanguage OWL

• An OWL reasoner is built in to answer questions and detectinconsistencies

• Special editor for writing ACE statements

• Has been extended to support multilinguality


Monolingual AceWiki: Screenshot


Attempto Controlled English (ACE)

Subset of natural English:

• Conjunction, disjunction, negation, if-then, ...

• Anaphoric references: pronouns, definite noun phrases, variables

• Quantifiers: every, no, at least 3, ...

• Content words: proper names, nouns, verbs, adjectives, ...

Grammar is fixed, but users can change content words.

Deterministic ambiguity handling:

• Anaphora resolution (France borders Spain and it bordersPortugal.)

• Quantifier scope (Every country borders a country.)

• Attachment (Every EU-country borders a country that is aEU-country and is a NATO-country.)

Well-defined translations to and from first-order logic, OWL, ...


Predictive Editor


Consistency Checking

Consistency of the knowledge base is very important, because it is aprerequisite for all other reasoning tasks.

AceWiki ensures consistency by checking every new statement:


Question Answering

AceWiki supports simple wh-questions:


Monolingual AceWiki: Demo

http://attempto.ifi.uzh.ch/acewiki/



ACE Reasoning via Translation to OWL

Every country that does not border a sea is a landlocked-country.

SubClassOf(

ObjectIntersectionOf(

:country

ObjectComplementOf(

ObjectSomeValuesFrom(

:border

:sea

)

)

)

:landlocked-country

)

Which country is a landlocked-country?


:country

:landlocked-country

)


Expressiveness versus Efficiency

Trade-off: Expressiveness/Complexity ⇔ Decidability/Efficiency

• First-order logic: expressive, undecidable, very inefficient

• Description Logics, OWL: less expressive, decidable, inefficient

• OWL Profiles: even less expressive, decidable, efficient

AceWiki can use full OWL or an OWL profile for reasoning.Sentences that are more complex get a red triangle and are ignoredfor reasoning:


Evaluation

Two small usability experiments with earlier versions of AceWiki:

• Altogether 26 untrained participants

• Task: Collaborative creation of a knowledge base

Results:

• 78%-81% of the sentences were correct and sensible

• 61%-70% of them were complex (containing negations,implications, disjunctions or number restrictions)

• Creation of a correct sentence every 5–6 minutes

• Definition of a new word every 5–7 minutes

→ Even untrained users can effectively use AceWiki


Multilingual AceWiki: AceWiki-GF

General ideas:

• Make wiki content available in different languages

• Automatically translated content using rule-based machinetranslation: Grammatical Framework (GF)

• Language switching like in Wikipedia

• Localization of the user interface


Grammatical Framework (GF)

GF is a framework for multilingual grammar engineering:

• Rule-based (i.e. not statistical)

• Functional programming language optimized to handle naturallanguage

• Resource Grammar Library implementing common morphologicaland syntactic structures

• Mildly context sensitive

• Bidirectional translations: concrete language ⇔ abstract syntax


GF grammars and translations

GF grammars consist of:

• One language-neutral abstract syntax

• Multiple concrete syntaxes that implement the given abstractcategories, specifying words, word order, agreement, etc.

Example

border : Country -> Country -> Relation

English: border x y = x!Nom + "borders" + y!Nom

Estonian: border x y = x!Gen + "naaber on" + y!Nom

GF translations consist of:

• First, parse a string in the original language to a tree (or trees)in the abstract syntax

• Then, linearize these trees as strings in the target language


Multilingual AceWiki: Screenshot


GF Resource Grammar Library (RGL)

• Morphology and syntax for ∼30 languages via language-neutralAPI

• Developers do not need detailed knowledge of the languagesthat they want to support in their application


Implementation of AceWiki-GF

Integration of ACE with GF (ACE-in-GF):

• Implemented a multilingual grammar of ACE in the GFframework

• Covered the languages supported by the GF resource grammar

• Not fine-tuned to any particular language (apart from ACE)

Integration of AceWiki with GF (AceWiki-GF):

• Implemented connection to GF tools (GF Webservice / CloudService)

• Added support for the management of multilinguality, ambiguity,grammar


Multilingual AceWiki: Demo

http://attempto.ifi.uzh.ch/acewiki-gf/



ACE-in-GF

An ACE grammar implemented in GF adds multiple natural languagesas front-ends to ACE. As a result, these languages can be mapped toand from various formal languages already supported by ACE.


ACE-in-GF: Example

German: Jedes Land, das nicht an ein Meer grenzt, ist einBinnenland.

ACE-in-GF tree:baseText (sText (s (vpS (everyNP (relCN (cn_as_VarCN country_CN)

(neg_predRS which_RP (v2VP border_V2 (thereNP_as_NP

(aNP (cn_as_VarCN sea_CN))))))) (npVP (thereNP_as_NP

(aNP (cn_as_VarCN landlocked_country_CN)))))))

ACE: Every country that does not border a sea is alandlocked-country.

OWL:SubClassOf(


:country

ObjectComplementOf(

ObjectSomeValuesFrom( :border :sea )

)

)

:landlocked-country

)


ACE-in-GF: Implementation

Implementation of the ACE syntax:

• Extension of Angelov and Ranta (CNL 2009)

• Focus on the subset of ACE that can be mapped to OWL

• Almost 100% coverage at almost 0% ambiguity

Support most RGL languages:

• Bulgarian, Catalan, Chinese, Danish, Dutch, English, Finnish,French, German, Greek, Hindi, Italian, Latvian, Norwegian,Polish, Romanian, Russian, Spanish, Swedish, Thai, Urdu

• RGL-based design provides automatic increase in quality andlanguage-coverage over time

Status

• Some precision problems, e.g. with anaphoric references

• Ambiguity and coverage problems in some languages


Ambiguity Resolution


Evaluation of ACE-in-GF

Design

• Generated ∼100 ACE sentences/questions and automaticallytranslated them to all the languages

• Full coverage of all the grammar functions• Large coverage of OWL axiom structures (subclass, range,

domain, transitivity, ...)

• Measured translation accuracy from ACE to other languages

• Used Google Translate as the baseline

• 20 human evaluators (2 per language) as the gold standard

Results

• Participants preferred ACE-in-GF translations to Googletranslations and post-edited them less

• Many edits were stylistic


Evaluation of ACE-in-GF: Results


Evaluation of AceWiki-GF

Hypothesis: A group of users reaches almost the same level of agreement

on the content of an article presented to them in different languages as

when the article is presented to all of them in the same language.

Design

• Based on a 500-word lexicon on European geography in threelanguages: English, German and Spanish

• 30 participants accessed AceWiki-GF and wrote sentences intheir language (10 participants for each language)

• They had to enter true and false sentences and tag them as such

• In a post-editing task, each participant checked the output oftwo other participants: one translated from another languageand one written in the same language (true/false tags wereremoved and sentences shuffled)


Evaluation of AceWiki-GF: Results

• 30 participants spent on average 37 minutes using AceWiki-GF,creating in total 316 sentences

• Definition of agreement level: (Tk + Fd)/SS is the total number of sentences, Tk the number of sentences marked as

true and kept, and Fd the ones marked as false and deleted

• Agreement level with and without translation: 84.0% and 82.2%(difference is not significant)

• Assumption: translation introduces a constant translation errorrate r that has the effect that the agreement level is (1− r)× ainstead of a

• New hypothesis: The translation error rate is less than 5%.

• p-value with one-tailed Wilcoxon signed rank test: 0.046

• With AceWiki-GF, translation error rate is less than 5%!


Evaluation of AceWiki-GF: Feedback

Questionnaire for the participants contained these questions:

1 Was AceWiki Geography easy or difficult to use in general?

2 Was the sentence editor easy or difficult to use?

3 Was creating true and false statements easy or difficult toperform?

Possible answers: “very difficult” (0), “difficult” (1), “medium” (2),“easy” (3), and “very easy” (4)

Results:

1 Average: 2.93 (∼“easy”)




Links

ACE parser (APE) source code: https://github.com/Attempto/APE

ACE-in-GF source code: http://github.com/Attempto/ACE-in-GF

AceWiki and AceWikiGF

• Source code: http://github.com/AceWiki/AceWiki

• Demos (non-GF): http://attempto.ifi.uzh.ch/acewiki/

• Demos (GF): http://attempto.ifi.uzh.ch/acewiki-gf/

MOLTO project web site: http://www.molto-project.eu

Attempto project web site: http://attempto.ifi.uzh.ch

Grammatical Framework project

• Web site: http://www.grammaticalframework.org

• GF Summer School, August 2013 in Germany:http://school.grammaticalframework.org/2013/


https://github.com/Attempto/APE

http://github.com/Attempto/ACE-in-GF

http://github.com/AceWiki/AceWiki



http://www.molto-project.eu

http://attempto.ifi.uzh.ch

http://www.grammaticalframework.org

http://school.grammaticalframework.org/2013/

Thank you for your Attention!

Questions?


Lifestyle

A Multilingual Semantic Wiki based on Attempto Controlled English and Grammatical Framework