Error-Tolerant RDF Subgraph Matching for Adaptive Presentation of Linked Data on Mobile

1. Error-Tolerant RDF Subgraph Matching for Adaptive Presentation of Linked Data on Mobile Luca Costabello

2. 2 Mobile Guide Museum Triplestore “Is it optimized for my tablet?” “Does it highlight practical information when I am on my way?” “Does it have a visually-impaired mode?” Example: An RDF-based Mobile Guide for Museums

3. 3 How to enable context-aware adaptation for Linked Data consumption? Research Challenges 1.  Model context-aware presentation metadata? 2.  Select proper presentation metadata at runtime? “Context” as in [Dey 2001]

4. 4 Modeling Presentation Metadata 1 Selecting Presentation Metadata with Error-Tolerant Matching 2 Evaluation 3 Conclusions 4

6. 6 NAC Laakko Chen Zhang Chamaleon Butter Paternò MIMOSA CAMB Adipat COIN CSSMedia Queries PRISSMA (OurSystem) Linked Data support ✓ Context-awareness ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Standard Languages ✓ ✓ ✓ ✓ ✓ ✓ ✓ Runtime adaptation ✓ ✓ ✓ ✓ Multimodality ✓ Client-side only  (for privacy preservation) ✓ ✓ ✓ ✓ ✓ Evaluation ✓ ✓ ✓ ✓ ✓ Adaptive Presentation Frameworks for the Web

7. 7 Presentation Frameworks for the Semantic Web Haystack Noadster Surrogates Declarative approach ✓ ✓ Domain Independence ✓ ✓ ✓ Standard Languages ✓ ✓ Context Awareness Automatic stylesheets Evaluation Distribution Multimodality ✓ Xenon Tal4Rdf LESS Hidethe Stack LDVM ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ Fresnel ✓ ✓ ✓ ✓ PRISSMA (OurSystem) ✓ ✓ ✓ ✓ ✓ ✓

8. Fresnel [Pietriga et al. 2006] 8 Illustration from [Pietriga et al. 2006] Content formatting and additional content" Content selection and ordering" Styling instructions for fonts, colors, and borders" Presentation Metadata Vocabulary and Rendering Engine for RDF

9. 9 Our Contribution: Extending Fresnel with PRISSMA* Context PRISSMA Prism Context Description PRISSMA Context *Presentation of Resources for Interoperable Semantic and Shareable Mobile Adaptability

10. Extending Fresnel with PRISSMA 10 Context fresnel:Lens fresnel:Format fresnel:group fresnel:group Environment environment Device device User user ns.inria.fr/prissma fresnel:Group fresnel:purpose Fresnel PRISSMA (Our Contribution) Contextfresnel:Purpose Prismfresnel:Group owl:equivalentClass fresnel:purpose owl:equivalentClass

11. 11 Example A Prism for showing and styling titles and authors of paintings metadata accessed from inside the museum.

12. 12 :paintingPrism a prissma:Prism, fresnel:Group ;! fresnel:stylesheetLink <style.css> ;! fresnel:purpose :atTheMuseum .! ! :paintinglens a fresnel:Lens;! fresnel:group :PaintingPrism ;! fresnel:classLensDomain art:Painting ;! fresnel:showProperties (dc:title! dcn:author) .! ! :depictionFormat a fresnel:Format ;! fresnel:group :paintingPrism ;! fresnel:propertyFormatDomain dc:title ;! fresnel:valueStyle ”title"^^fresnel:styleClass .! ! :atTheMuseum a prissma:Context ;! prissma:environment :museumEnv .! ! :museumEnv a prissma:Environment ;! prissma:poi :museumGeo .! ! :museumGeo geo:lat "48.86034" ;! geo:long "2.337599" ;! prissma:radius ”200" .! Lens Format Context prissma:environment 2.337599 48.86034 200 :museumGeo geo:lat geo:long prissma:radius prissma:poi prissma:Environment prissma:Context :atTheMuseum :museumEnv A Prism for showing and styling titles and authors of paintings metadata accessed from inside the museum. Example:

13. Examples  PRISSMA Browser for Android 13 Smartphone, user walking in museum town. Tablet, user at home. github.com/lukostaz/prissma-browser/

15. Selecting Presentation Metadata 15 :smartphoneMoving :tabletAtHome :maleVisitorAtTheMuseum :actualContext

16. 16 Ambiguity Incompleteness Selecting Presentation Metadata is tricky Sensor Noise 2.32434 48.843453 :poi geo:lat geo:long 10 prissma:radius 2.337599 48.86034 5 :poi geo:lat geo:long prissma:radius :user1 "computers" foaf:interest :user1 "computer science" foaf:interest :user1 :Karl :Anita prissma:nearbyEntity :John :user1 :Karl :Anita prissma:nearbyEntity Prism Actual Need Error-tolerant matching

17. 17 Error-tolerant matching for RDF Graphs iSPARQL Silk Zou RDF-speciﬁc ✓ ✓ ✓ Data Heterogeneity Client-side Execution  (for privacy preservation) Incremental index updates ✓ Selective matching cache PRISSMA ✓ ✓ ✓ ✓ Messmer ✓

18. Our Contribution: Adapting Messmer to RDF and Mobile Context Optimal error-tolerant subgraph isomorphisms based on graph edit distance. 18 • Atomic element might be a graph: Context Units •  Core Context Classes •  Entities •  Literals •  Geo •  Time • Customized Cost Functions •  Strings (Monge-Elkan) •  Geographic (Haversine distance + Decay) •  Temporal (Interval Inclusion + Decay) •  Missing nodes 2.32434 48.843453 :poi geo:lat geo:long 10 prissma:radius Our Extensions: [Messmer et al. 98]

19. Prism Selection - Step 1: Decomposition (i.e. Index Building) 19 prissma:environment 2.337599 48.86034 200 :museumGeo geo:lat geo:long prissma:radius prissma:poi prissma:Environment prissma:Context :atTheMuseum :museumEnv prissma:Context 0 48.86034 -2.337599 200 geo:lat geo:lon prissma:radius 1 :museumGeo prissma:Environment 2 {3,1,2,{prissma:poi}} {4,0,3,{prissma:environment}} :atTheMuseum Context Units

20. Prism Selection – Step 2: Online Search Algorithm! 1  foreach context unit S in D do! 2  compute_subgraph_isomorphisms(S,GI)! 3  ! 4  while C(fcheapest)< T { ! 5  if S1 is Prism then! 6  R.add(S1)! 7  ! 8  foreach child of S1 do! 9  fchild= combine(fS1,fS2)! 10  }! 11  return R! 20 prissma:Context 0 48.86034 -2.337599 200 geo:lat geo:lon prissma:radius 1 :museumGeo prissma:Environment 2 {3,1,2,{prissma:poi}} {4,0,3,{prissma:environment}} :atTheMuseum prissma:environment 2.32434 48.843453 :actualPOI geo:lat geo:long prissma:poi :ActualCtx :actualEnv 10 prissma:radius C=0! C=0.34! C=0! 1. Compute context units isomorphisms costs

21. prissma:Context 0 48.86034 -2.337599 200 geo:lat geo:lon prissma:radius 1 :museumGeo prissma:Environment 2 {3,1,2,{prissma:poi}} {4,0,3,{prissma:environment}} :atTheMuseum Prism Selection: Search Algorithm! 1  foreach context unit S in D do! 2  compute_subgraph_isomorphisms(S,GI)! 3  ! 4  while C(fcheapest)< T { ! 5  if S1 is Prism then! 6  R.add(S1)! 7  ! 8  foreach child of S1 do! 9  fchild= combine(fS1,fS2)! 10  }! 11  return R! 21 prissma:environment 2.32434 48.843453 :actualPOI geo:lat geo:long prissma:poi :ActualCtx :actualEnv 10 prissma:radius C=0! C=0.34! C=0! C=0.17! C=0.09! T=0.6! ✓ ✓ ✓ ✓ ✓ 2. Combine costs C < T --> Match!

23. Evaluation: Memory Consumption 23 0 50 100 150 200 250 300 0.1 0.3 0.5 0.7 0.9 DecompositionItems Percentage of common context units Total decomposition Items Context Units (decomposition) Context Units (raw prisms) 0 5 10 15 20 25 0.1 0.3 0.5 0.7 0.9 Memory[KB] Percentage of common context units PRISSMA decomposition Jena Models

24. Evaluation: Response Time 24 If prisms are completely different if prisms are highly similar →

26. 26 Limitations and Future Work Prisms Distribution:   Linked Presentation Metadata. Modeling Presentation Metadata 1 Selecting Presentation Metadata with Error-Tolerant Matching 2 Evaluation 3 User acceptability evaluation campaign. Machine learning to optimize cost functions parameterization. Beyond Fresnel: support for other presentation engines Thanks. wimmics.inria.fr/projects/prissma @lukostaz