Presented at the LeDa-SwAn Workshop at ESWC2015 http://cs.unibo.it/ledaswan2015 #ledaswan2015 Licences are a crucial aspect of the information publishing process in the web of (linked) data. Recent work on modeling of policies with semantic web languages (RDF, ODRL) gives the opportunity to formally describe licences and reason upon them. However, choosing the right licence is still challenging. Particularly, understanding the number of features - permissions, prohibitions and obligations - constitute a steep learning process for the data provider, who has to check them individ- ually and compare the licences in order to pick the one that better fits her needs. The objective of the work presented in this paper is to reduce the e↵ort required for licence selection. We argue that an ontology of licences, organized by their relevant features, can help providing support to the user. Developing an ontology with a bottom-up approach based on Formal Concept Analysis, we show how the process of licence selection can be simplified significantly and reduced to answering an average of three/five key questions.

1. A Bottom-Up Approach for Licences
Classification and Selection
1
Enrico Daga (KMi-OU)
Mathieu d’Aquin (KMi-OU)
Aldo Gangemi (CNR & Universite’ Paris13)
Enrico Motta (KMi-OU)
June
1st,
2015
Interna0onal
Workshop
on
Legal
Domain
And
Seman0c
Web
Applica0ons
ESWC
2015
Workshop
hCp://cs.unibo.it/ledaswan2015

2. Background
• Licences are important in the web of (linked) data
• We can describe licences/policies (RDF+ODRL)
• Exploiting these descriptions for license selection
is hard due to the high number of different
features
2

3. Question
How can we reduce the effort for licence
identification and selection?
3

4. Hypothesis
An ontology defining relevant classes of
licences, formed on the basis of the key
features of the instances, should facilitate the
selection and identification of a suitable licence.
4

5. Methodology
A bottom-up approach to ontology construction
• RDF License Database
• Ontology production with Contento
• Based on Formal Concept Analysis
• User can annotate and prune concepts
• Produces an OWL Ontology
• License Picker Ontology (LiPiO)
• Evaluation: License Picker Webapp
5

6. Formal Concept Analysis (FCA)
• A data analysis method
• Studies how objects can be hierarchically grouped together
according to their common attributes
• Input is a Formal Context
– a binary matrix of objects/attributes
• Basic unit is a Concept:
– (O,A) => (Extension,Intension)
– Operator ’ … (O,A) is a concept when O’=A and A’=O
• Classifies concepts hierarchically in a concept lattice
– Top: all objects, no attr, bottom: all attributes, no obj
6

7. 7
Contento
http://bit.ly/contento-tool
Support the user in the generation and curation of concept
lattices from formal contexts and use them as semantic web
ontologies.
Formal
Context
Concept
LaNce
Modeling
(Naming
&
Pruning)
Export
as
OWL
Ontology

8. 8
Contento
http://bit.ly/contento-tool
Support the user in the generation and curation of concept
lattices from formal contexts and use them as semantic web
ontologies.
Formal
Context
Concept
LaNce
Modeling
(Naming
&
Pruning)
RDF
Licence
Database
Licence
Picker
Ontology
Export
as
OWL
Ontology
Fo Co MR LicEx

9. RDF License Database
http://datahub.io/dataset/rdflicense *
~140 licences expressed in RDF/ODRL
9
<hCp://purl.org/NET/rdflicense/cc-­‐by-­‐nc4.0>
a
odrl:Policy
;
rdfs:label
"Crea0ve
Commons
CC-­‐BY-­‐NC"
;
rdfs:seeAlso
<hCp://crea0vecommons.org/licenses/by-­‐nc/4.0/legalcode>
;
cc:legalcode
<hCp://crea0vecommons.org/licenses/by-­‐nc/4.0/>
;
dct:alterna0ve
"CC
BY-­‐NC"
;
dct:hasVersion
"4.0"
;
dct:language
<hCp://www.lexvo.org/page/iso639-­‐3/eng>
;
dct:publisher
"Crea0ve
Commons"
;
dct:0tle
"Crea0ve
Commons
-­‐
ACribu0on-­‐NonCommercial
4.0
Interna0onal
-­‐
CC
BY-­‐NC
4.0"@en
;
odrl:permission
[
odrl:ac0on
cc:Distribu8on
,
ldr:extrac8on
,
ldr:reu8liza8on
,
cc:Deriva8veWorks
,
cc:Reproduc8on
;
odrl:duty
[
odrl:ac0on
cc:ABribu8on
,
cc:No8ce]
]
;
odrl:prohibi8on
[
odrl:ac0on
cc:CommercialUse
]
;
foaf:logo
<hCp://i.crea0vecommons.org/l/by-­‐nc/2.0/88x31.png>
.
Fo Co MR LicEx
(*) Victor Rodrıguez-Doncel, Serena Villata, and Asuncion Gomez-Ṕerez. A dataset of RDF licenses.
In Rinke Hoekstra, editor, Legal Knowledge and Information Systems. JURIX 2014: The Twenty-Seventh Annual Conference. IOS Press, 2014.

10. Formal Context
Objects: Apache 2.0, CC-A-SA 3.0, …
Attributes: duty attribution, permission Copy, prohibition derive, …
10
RDF
Licence
Database
Licence,Policy,Bool
Apache,Duty
No0ce,True
…
(as
CSV)
Fo Co MR LicEx

11. Concept Lattice
• Applying FCA, a concept lattice is produced
• The top concept representing All the licences, while the bottom
concept, None, includes all the attributes, and no licence.
• However, this lattice need to be interpreted…
11
Fo Co MR LicEx

12. Modeling: Naming & Pruning
• Inspect each concept
• If it is meaningful annotate it
– eg: “should others be allowed
to distribute the work?”
• … otherwise delete it
– and the hierarchy is adjusted
accordingly
– objects are present in direct
upper concepts, attributes in
direct lower
12
Fo Co MR LicEx

13. • Approach: a concept is
meaningful if it’s intent
introduces new features
(policies)
• If not:
– it is a union of the intents of the
respective upper concepts,
– the respective licences will be
present in (at least one of) the
upper concepts,
– no new question need to be
asked to identify them.
13
Modeling: Naming & Pruning
Fo Co MR LicEx

14. Modeling: Naming & Pruning
• With this process the lattice has been reduced significantly.
• Almost 20% of the initial lattice
• Labels being synthetic names referring to policies/attributes that have
been introduced in that point of the hierarchy
• Each concept has a Question
14
Fo Co MR LicEx

15. Export as OWL Ontology
15
rdfs:subClassOf
rdf:type
ex:has-­‐aBribute
.
.
.
give semantics!
Fo Co MR LicEx

16. contento_ns:7582 rdf:type contento:Concept ;
rdfs:label "Copyleft" ;
rdfs:comment "Should the licence require to share any derived or combined content under the
same terms?" ;
rdfs:subClassOf contento_ns:7856 ,
contento_ns:7678 ,
contento_ns:7956 .
contento_ns:7586 rdf:type contento:Concept ;
rdfs:label "Read" ;
rdfs:comment "Should the licence permit to read (access) the data?" ;
rdfs:subClassOf contento_ns:7648 .
contento_ns:7632 rdf:type contento:Concept ;
rdfs:label "ND" ;
rdfs:comment "Should the licence prohibit derivative works?" ;
The Licence Picker Ontology
http://bit.ly/licence-picker-ontology
Can be exploited as a decision tree!
16
Focus is on Key Questions
Fo Co MR LicEx

17. Evaluation The Licence Picker Webapp
http://bit.ly/licence-picker-webapp
17
The user is engaged in
answering questions regarding
her requirements
By applying the Licence Picker
Ontology (LiPiO), this task is
reduced to answering an average
of 3/5 questions and assessing
the best licence from a small set
of choices.

18. Conclusions and Future Work
• A bottom-up approach on ontology building in this scenario opens
new interesting challenges
• The RDF description of licences is an ongoing work
• Data has been curated in advance (harmonised)
• Data has impact on the whole process!
– explore methods to automate some of the curation tasks
(especially pruning)
– to integrate changes in the formal context incrementally
– to support the ontology designer in the adaptation of the ontology
• New features: type of asset, jurisdiction …
• Contento: a generic tool, need user-based evaluation
18

19. Thank you
Enrico Daga
enrico.daga@open.ac.uk