The RDF* and SPARQL* Approach to Annotate Statements in RDF and to - - PowerPoint PPT Presentation

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The RDF* and SPARQL* Approach to Annotate Statements in RDF and to - - PowerPoint PPT Presentation

May 15, 2023 257 likes •527 views

The RDF* and SPARQL* Approach to Annotate Statements in RDF and to Reconcile RDF and Property Graphs Olaf Hartjg @olafiartjg Not supported natjvely in the RDF data model mentioned Kubrick Welles influencedBy name = "Stanley

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The RDF* and SPARQL* Approach

to Annotate Statements in RDF and to Reconcile RDF and Property Graphs

Olaf Hartjg

@olafiartjg

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2 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Not supported natjvely in the RDF data model

Welles name "Orson Welles" . Welles mentioned Kubrick . Kubrick name "Stanley Kubrick" . Kubrick influencedBy Welles . ??? significance 0.8 .

Kubrick Welles influencedBy significance = 0.8 name = "Stanley Kubrick" name = "Orson Welles" mentioned

  • RDF triples:
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3 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Main Use Case: Statement-Level Metadata

Welles name "Orson Welles" . Welles mentioned Kubrick . Kubrick name "Stanley Kubrick" . Kubrick influencedBy Welles . ??? significance 0.8 .

Kubrick Welles influencedBy significance = 0.8 name = "Stanley Kubrick" name = "Orson Welles" mentioned

  • RDF triples:
  • Certainty scores
  • Weights
  • Temporal restrictions
  • Provenance information
  • etc.
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4 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Standard RDF Reifjcatjon

Welles name "Orson Welles" . Welles mentioned Kubrick . Kubrick name "Stanley Kubrick" . Kubrick influencedBy Welles . s significance 0.8 . s rdf:type rdf:Statement . s rdf:subject Kubrick . s rdf:predicate influencedBy . s rdf:object Welles .

Kubrick Welles influencedBy significance = 0.8 name = "Stanley Kubrick" name = "Orson Welles" mentioned

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5 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Queries?

SELECT ?x WHERE { ?x influencedBy Welles . ?t significance ?sig . ?t rdf:type rdf:Statement . ?t rdf:subject ?x . ?t rdf:predicate influencedBy . ?t rdf:object Welles . FILTER ( ?sig > 0.7 ) } Example 1: List all people that Welles had a significant influence on.

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6 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Queries?

SELECT ?x WHERE { ?x influencedBy Welles . Welles influencedBy ?x . ?t1 rdf:type rdf:Statement . ?t1 rdf:subject ?x . ?t1 rdf:predicate influencedBy . ?t1 rdf:object Welles . ?t1 significance ?sig1 . ?t2 rdf:type rdf:Statement . ?t2 rdf:subject Welles . ?t2 rdf:predicate influencedBy . ?t2 rdf:object ?x . ?t2 significance ?sig2 . FILTER (?sig1 > 0.7 && ?sig2 > 0.7) } Example 2:

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7 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Other Proposals: Single-Triple Named Graphs

  • Example:

– Query:

g1 { Kubrick influencedBy Welles } g1 significance 0.8 . SELECT ?x WHERE { GRAPH ?g { ?x influencedBy Welles } ?g significance ?sig . FILTER ( ?sig > 0.7 ) }

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8 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Other Proposals: Singleton Propertjes

  • Example:

– Query:

Kubrick influencedBy Welles . Kubrick p1 Welles . p1 singletonPropertyOf influencedBy . p1 significance 0.8 . SELECT ?x WHERE { ?x influencedBy Welles . ?x ?p Welles . ?p singletonPropertyOf influencedBy . ?p significance ?sig . FILTER ( ?sig > 0.7 ) }

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9 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Our Proposal: Nested Triples

<<Kubrik influencedBy Welles>> significance 0.8

subject predicate

  • bject

Kubrick influencedBy Welles . s rdf:type rdf:Statement . s rdf:subject Kubrick . s rdf:predicate influencedBy . s rdf:object Welles . s significance 0.8 .

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10 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

… and Nested Triple Patuerns

SELECT ?x WHERE { ?x influencedBy Welles . ?t significance ?sig . ?t rdf:type rdf:Statement . ?t rdf:subject ?x . ?t rdf:predicate influencedBy . ?t rdf:object Welles . FILTER ( ?sig > 0.7 ) } SELECT ?x WHERE { <<?x influencedBy Welles>> significance ?sig FILTER (?sig > 0.7) }

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11 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Grouping of Patuerns with the Same Subject

SELECT ?x WHERE { ?x influencedBy Welles . ?t significance ?sig ; rdf:type rdf:Statement ; rdf:subject ?x ; rdf:predicate influencedBy ; rdf:object Welles . FILTER ( ?sig > 0.7 ) } SELECT ?x ?sig ?src WHERE { <<?x influencedBy Welles>> significance ?sig ; source ?src . }

  • By the standard SPARQL syntax, we may write:
  • Hence, we may easily query for multiple metadata triples:
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12 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Extension of the BIND Clause

  • Assign matching triples to variables:

SELECT ?x ?sig ?src WHERE { BIND(<<?x influencedBy Welles>> AS ?t) ?t significance ?sig ; source ?src . } SELECT ?x ?sig ?src WHERE { <<?x influencedBy Welles>> significance ?sig ; source ?src . }

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13 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Extension of the BIND Clause

  • Assign matching triples to variables:
  • Now, we may even output triples in query results:

SELECT ?x ?sig ?src WHERE { BIND(<<?x influencedBy Welles>> AS ?t) ?t significance ?sig ; source ?src . } SELECT ?t ?c WHERE { BIND(<<?x influencedBy Welles>> AS ?t) ?t certainty ?c . }

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14 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Example Query 2 Revisited

SELECT ?x WHERE { ?x influencedBy Welles . Welles influencedBy ?x . ?t1 rdf:type rdf:Statement . ?t1 rdf:subject ?x . ?t1 rdf:predicate influencedBy . ?t1 rdf:object Welles . ?t1 significance ?sig1 . ?t2 rdf:type rdf:Statement . ?t2 rdf:subject Welles . ?t2 rdf:predicate influencedBy . ?t2 rdf:object ?x . ?t2 significance ?sig2 . FILTER (?sig1 > 0.7 && ?sig2 > 0.7) }

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15 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Example Query 2 Revisited

SELECT ?x WHERE { ?x influencedBy Welles . Welles influencedBy ?x . ?t1 rdf:type rdf:Statement . ?t1 rdf:subject ?x . ?t1 rdf:predicate influencedBy . ?t1 rdf:object Welles . ?t1 significance ?sig1 . ?t2 rdf:type rdf:Statement . ?t2 rdf:subject Welles . ?t2 rdf:predicate influencedBy . ?t2 rdf:object ?x . ?t2 significance ?sig2 . FILTER (?sig1 > 0.7 && ?sig2 > 0.7) } SELECT ?x WHERE { <<?x influencedBy Welles>> significance ?sig1 . <<Welles influencedBy ?x>> significance ?sig2 . FILTER (?sig1 > 0.7 && ?sig2 > 0.7) }

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16 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Two Perspectjves on RDF* and SPARQL*

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

– Extension of the

RDF data model and of SPARQL to capture the notion

  • f nested triples

– Supported by

Blazegraph

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

– Can be parsed directly

into standard RDF and SPARQL

– Can be implemented

easily by a small wrapper on top of any existing RDF DBMS

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17 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Further Possible Applicatjons of SPARQL*

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

  • Query datasets that use RDF reification

(or singleton properties, or single-triple named graphs)

– By straightforward translation into ordinary SPARQL queries

  • Query Property Graphs including their edge properties

– By translation into Gremlin, Cypher, etc.

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18 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Contributjons (Perspectjve 1)

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • Definition of desirable properties of RDF*-to-RDF mappings

– Information preservation and query result preservation

  • Definition of RDF reification related mappings and

proof that they possess the desirable properties

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19 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Contributjons (Perspectjve 2)

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • Formalization of the RDF* data model

– Extends the RDF data model with the notions

  • f an RDF* triple and an RDF* graph
  • Definition of syntax and formal semantics of SPARQL*

– Extends the semantics of SPARQL by defining the

result of a SPARQL* query Q over an RDF* graph G eval(Q,G) = { m1, m2, …, mn }

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

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20 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Contributjons (Perspectjve 2), cont’d

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

  • Results regarding redundancy in RDF* graphs

– Example:

<<Kubrik influencedBy Welles>> certainty 0.8 .

Kubrik influencedBy Welles .

– Query results are equivalent no matter whether

there is redundancy in an RDF* graph or not

redundant

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21 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Contributjons in Detail

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL

  • O Hartig: “Foundations of RDF* and SPARQL* - An Alternative

Approach to Statement-Level Metadata in RDF.” In Proc. of 11th Alberto Mendelzon Int. W. on Foundations of Data Mgmt (AMW), 2017.

  • Olaf Hartig: “Reconciliation of RDF* and Property Graphs.” In CoRR

abs/1409.3288, 2014

–

Formal definition of direct mappings b/w RDF* and Property Graphs

  • O Hartig and Bryan Thompson: “Foundations of an Alternative

Approach to Reification in RDF.” CoRR abs/1406.3399, 2014

–

Specifies Turtle*

–

All relevant extensions of the SPARQL spec

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22 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Hold on!

… is this all theory only???

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23 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

Implementatjons

  • Full support in the Blazegraph triple store

– “Reification done right” (RDR)

  • Full support in Cambridge Semantics’ AnzoGraph
  • RDF* Tools (https://github.com/RDFstar/RDFstarTools)

– RDF* / SPARQL* extension of Apache Jena

– Conversion tools (RDF* ↔ RDF, SPARQL* → SPARQL) – Simple query execution tool (SPARQL* over RDF*)

  • RDF*-PG-Connection Tools (

https://github.com/RDFstar/RDFstarPGConnectionTools)

– Conversion tools (RDF* ↔ PGs)

  • Other vendors have indicated interest in standardizing

something along the lines of RDF* & SPARQL*

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24 Olaf Hartjg – The RDF*/SPARQL* Approach to Statement-Level Metadata in RDF

RDF* and SPARQL* in a Nutshell

  • 2. A logical model in its own

right, with the possibility of a dedicated physical schema

  • 1. Purely syntactic sugar on

top of standard RDF and SPARQL <<Kubrik influencedBy Welles>> significance 0.8

subject predicate

  • bject

SELECT ?x WHERE { <<?x influencedBy Welles>> significance ?sig FILTER (?sig > 0.7) }

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