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Certain Answers for SPARQL with Blank Nodes
Published on 2018-11-222729 Views
Blank nodes in RDF graphs can be used to represent existential values known to exist but whose identity remains unknown. A prominent example of such usage can be found in the Wikidata dataset where, e
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Presentation
Certain Answers for SPARQL with Blank Nodes00:00
Example 1: Beowulf was written by somebody00:07
The meaning of blank nodes - 100:29
The meaning of blank nodes - 200:40
Example 2: Who killed her? - 101:00
Example 2: Who killed her? - 201:16
Questions02:15
Example 3: Women not killed by athletes - 102:36
Example 3: Women not killed by athletes - 202:55
Example 3: Women not killed by athletes - 303:13
Example 3: Women not killed by athletes - 404:17
Example 3: Women not killed by athletes - 504:44
Recall the complexity gap!04:55
The studied solution05:17
Approximating certain and possible answers05:42
Approximation05:57
Over approximation of poss(R on S) ∼ poss(R) on poss(S) 05:59
Under approximation of cert(R on S) ∼ cert(R) on cert(S) 06:13
Over approximation of poss(R − S) ∼ poss(R) − cert(S) 06:18
Under approximation of cert(R − S) ∼ cert(R) − poss(S)06:31
Translation from SPARQL to Relational Algebra06:40
Translation to fix queries06:57
Experiments07:34
General evaluation settings07:44
Basic unification experiments - 107:57
Basic unification experiments - 208:06
Basic unification experiments - 308:19
Basic unification experiments - 408:33
Wikidata survey: Numbers of Wikidata use-case queries09:06
Evaluation of Wikidata example queries10:50
Conclusions11:27