This presentation introduces AceWiki-GF, a semantic wiki based on controlled natural language that makes its knowledge base viewable and editable in different languages applying high-quality rule-based machine translation.

1. A Multilingual Semantic Wiki Based on
Controlled Natural Language
Tobias Kuhn
Chair of Sociology, in particular of Modeling and Simulation, ETH Zurich,
Switzerland
Insight, National University of Ireland, Galway
19 August 2014

2. About This Talk
This talk is mainly based on the following papers:
Kaarel Kaljurand and Tobias Kuhn. A Multilingual Semantic Wiki
Based on Attempto Controlled English and Grammatical Framework.
In Proceedings of the 10th Extended Semantic Web Conference
(ESWC). 2013.
http://purl.org/tkuhn/eswc2013acewikigf
Kaarel Kaljurand, Tobias Kuhn, and Laura Canedo. Collaborative
multilingual knowledge management based on controlled natural
language. Semantic Web. Accepted, to appear.
http://www.semantic-web-journal.net/system/files/swj524.pdf
Tobias Kuhn, ETH Zurich A Multilingual Semantic Wiki 2 / 27

3. Imagine ...
... that Wikipedia can check consistency and answer
questions about the contained knowledge, and
... that all content is instantly available in all
languages!
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4. • AceWiki is a semantic wiki
• Articles are written in Attempto Controlled English (ACE)
• These sentences are internally translated into the Semantic Web
language OWL
• An OWL reasoner is built in to answer questions and detect
inconsistencies
• Special editor for writing ACE statements
• Extended to support multilinguality
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5. Monolingual AceWiki: Screenshot
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6. 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 borders
Portugal.)
• Quantifier scope (Every country borders a country.)
• Attachment (Every EU-country borders a country that is an
EU-country and is a NATO-country.)
Well-defined translations to and from first-order logic, OWL, ...
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7. Predictive Editor
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8. Consistency Checking
AceWiki ensures consistency by checking every new statement:
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9. Question Answering
AceWiki supports simple wh-questions:
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10. Monolingual AceWiki: Demo
http://attempto.ifi.uzh.ch/acewiki/
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11. 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?
ObjectIntersectionOf(
:country
:landlocked-country
)
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12. 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
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13. Multilingual AceWiki: AceWiki-GF
General ideas:
• Make wiki content available in different languages
• Automatically translated content using high-quality rule-based
machine translation: Grammatical Framework (GF)
• Language switching like in Wikipedia
• Localization of the user interface
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14. Grammatical Framework (GF)
GF is a framework for multilingual grammar engineering:
• Rule-based
• Functional programming language (based on Haskell) optimized
to handle natural language
• Resource Grammar Library implementing common morphological
and syntactic structures
• Mildly context sensitive
• Bidirectional translations: concrete language ⇔ abstract syntax
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15. GF grammars and translations
GF grammars consist of:
• One language-neutral abstract syntax
• Concrete syntaxes specify words, agreement, word order, etc. by
implementing the abstract categories and functions
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
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16. Multilingual AceWiki: Screenshot
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17. Multilingual AceWiki: Demo
http://attempto.ifi.uzh.ch/acewiki-gf/
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18. ACE-in-GF
• Multiple controlled versions of natural languages that map to
ACE (and to each other)
• As a result, they can be bidirectionally mapped to various formal
languages already supported by ACE
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19. ACE-in-GF: Example
German: Jedes Land, das nicht an ein Meer grenzt, ist ein
Binnenland.
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 a
landlocked-country.
OWL:
SubClassOf(
ObjectIntersectionOf(
:country
ObjectComplementOf(
ObjectSomeValuesFrom( :border :sea )
)
)
:landlocked-country
)
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20. ACE-in-GF: Implementation
Implementation of the ACE syntax:
• Targeting the subset of ACE that can be mapped to OWL
• Almost 100% coverage at almost 0% ambiguity
Support of 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 and
language-coverage over time
Status
• Some precision problems, e.g. with anaphoric references
• Ambiguity and coverage problems in some languages
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21. 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 three
languages: English, German and Spanish
• 30 participants accessed AceWiki-GF and wrote sentences in
their 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 of
two other participants: one translated from another language
and one written in the same language (true/false tags were
removed and sentences shuffled); they were asked to remove all
false sentences
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22. Evaluation of AceWiki-GF: Results
30 participants spent on average 37 minutes using AceWiki-GF,
creating 316 sentences in total.
Definition of agreement level: (Tk + Fd )/S
S 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 (difference is not significant):
82.2%without translation
84.0%with translation
0% 25% 50% 75% 100%
agreement level
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23. Evaluation of AceWiki-GF: Results
Assumption: Translation introduces a constant translation error rate r
that has the effect of reducing the agreement level a to (1 − r) · a.
New hypothesis: The translation error rate is less than 5%.
78.1%with hypothetical translation (r = 5%)
84.0%with translation
0% 25% 50% 75% 100%
agreement level
p-value with one-tailed Wilcoxon signed-rank test: 0.046
→ With AceWiki-GF, translation error rate is less than 5%
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24. 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 to
perform?
Possible answers: “very difficult” (0), “difficult” (1), “medium” (2),
“easy” (3), and “very easy” (4)
Results:
1 Average: 2.93 (∼“easy”)
2 Average: 2.77 (∼“easy”)
3 Average: 2.70 (∼“easy”)
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25. The Future...?
Can we make a truly multilingual Wikipedia?
• Store main content in a semantic representation
• Verbalization in different languages
• All content is instantly available in all languages (once the
required vocabulary is defined)
• Breaking the current dominance of English and putting an end
to the lock-out of users speaking less widespread or
underrepresented languages
• Contributing to the Semantic Web
Related:
• http://www.wikidata.org
• http://meta.wikimedia.org/wiki/A_proposal_towards_a_
multilingual_Wikipedia
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26. 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 web site: http://attempto.ifi.uzh.ch
GF: http://www.grammaticalframework.org
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27. Thank you for your Attention!
If you are interested in Controlled Natural Languages,
come visit us at CNL 2014!
CNL
2014
Fourth Workshop on Controlled Natural Language
20–22 August 2014, Galway
http://attempto.ifi.uzh.ch/site/cnl2014/
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