Algebraic Structures for Capturing the Provenance of SPARQL Queries

Geerts, Floris; Unger, Thomas; Karvounarakis, Grigoris; Fundulaki, Irini; Christophides, Vassilis

doi:10.1145/2810037

Cited by 30 publications

(17 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To finish this brief overview on applications, we mention provenance [15,[19][20][21], which has a similar motivation, but different development, to axiom pinpointing. Originally developed for databases, and later extended to DLs, the goal of provenance is to track the origins for an answer to a query, in terms of the facts used to derive it.…”

Section: Applications and Variationsmentioning

confidence: 99%

Explaining Axiom Pinpointing

Peñaloza

2019

Lecture Notes in Computer Science

View full text Add to dashboard Cite

Axiom pinpointing refers to the task of finding the specific axioms in an ontology which are responsible for a consequence to follow. This task has been studied, under different names, in many research areas, leading to a reformulation and reinvention of techniques. In this work, we present a general overview to axiom pinpointing, providing the basic notions, different approaches for solving it, and some variations and applications which have been considered in the literature. This should serve as a starting point for researchers interested in related problems, with an ample bibliography for delving deeper into the details.

show abstract

Section: Applications and Variationsmentioning

confidence: 99%

Explaining Axiom Pinpointing

Peñaloza

2019

Lecture Notes in Computer Science

View full text Add to dashboard Cite

show abstract

“…Intuitively, one would expect an answer to query (15) to contain the label of an object in variable ? together with one of its supertypes in variable ?u.…”

Section: Analysis Of Dbpedia Logsmentioning

confidence: 99%

“…In particular, we now know much about evaluation [1,3,4,6,8,20,22,23,25,28,34,38], optimisation [8,9,12,13,24,27,35], federation [10,11], expressive power [2,20,21,25,36,39], and provenance tracking [15,16] for queries from various fragments and extensions of SPARQL. These studies have had a great impact in the community, in fact influencing the evolution of SPARQL as a standard.…”

Section: Introductionmentioning

confidence: 99%

Complexity and Expressive Power of Weakly Well-Designed SPARQL

Kaminski

Kostylev

2017

Theory Comput Syst

View full text Add to dashboard Cite

SPARQL is the standard query language for RDF data. The distinctive feature of SPARQL is the OPTIONAL operator, which allows for partial answers when complete answers are not available due to lack of information. However, optional matching is computationally expensive-query answering is PSPACE-complete. The well-designed fragment of SPARQL achieves much better computational properties by restricting the use of optional matching-query answering becomes coNPcomplete. On the downside, well-designed SPARQL captures far from all real-life queries-in fact, only about half of the queries over DBpedia that use OPTIONAL are well-designed. In the present paper, we study queries outside of well-designed SPARQL. We introduce the class of weakly well-designed queries that subsumes well-designed queries and includes most common meaningful non-well-designed queries: our analysis shows that the new fragment captures over 99% of DBpedia queries with OPTIONAL. At the same time, query answering for weakly welldesigned SPARQL remains coNP-complete, and our fragment is in a certain sense maximal for this complexity. We show that the fragment's expressive power is strictly in-between well-designed and full SPARQL. Finally, we provide an intuitive normal form for weakly well-designed queries and study the complexity of containment and equivalence.

show abstract

“…In [27], the authors formalized the syntax and semantics of SPARQL, presenting the first step towards understanding the fundamental properties of this language. This work was followed by studies about the complexity of query evaluation [34,23,5,29], query optimisation [22,30,12,13], query federation [10], expressive power analysis [3,31,20], and provenance tracking [17,18]. The theoretical study of SPARQL has impacted the Semantic Web in several ways, influencing the standard definition of SPARQL by the W3C and also the form in which users query RDF.…”

Section: Introductionmentioning

confidence: 99%

Designing a Query Language for RDF

Arenas

Ugarte

2016

Proceedings of the 35th ACM SIGMOD-SIGACT-SIGAI Symposium on Principles of Database Systems

View full text Add to dashboard Cite

When querying an RDF graph, a prominent feature is the possibility of extending the answer to a query with optional information. However, the definition of this feature in SPARQL -the standard RDF query language-has raised some important issues. Most notably, the use of this feature increases the complexity of the evaluation problem, and its closed-world semantics is in conflict with the underlying open-world semantics of RDF. Many approaches for fixing such problems have been proposed, being the most prominent the introduction of the semantic notion of weakly-monotone SPARQL query. Weakly-monotone SPARQL queries have shaped the class of queries that conform to the open-world semantics of RDF. Unfortunately, finding an effective way of restricting SPARQL to the fragment of weakly-monotone queries has proven to be an elusive problem. In practice, the most widely adopted fragment for writing SPARQL queries is based on the syntactic notion of well designedness. This notion has proven to be a good approach for writing SPARQL queries, but its expressive power has yet to be fully understood.The starting point of this paper is to understand the relation between well-designed queries and the semantic notion of weak monotonicity. It is known that every well-designed SPARQL query is weakly monotone; as our first contribution we prove that the converse does not hold, even if an extension of this notion based on the use of disjunction is considered. Given this negative result, we embark on the task of defining syntactic fragments that are weaklymonotone, and have higher expressive power than the fragment of well-designed queries. To this end, we move to a more general scenario where infinite RDF graphs are also allowed, so that interpolation techniques studied for first-order logic can be applied. With the use of these techniques, we are able to define a new operator for SPARQL that gives rise to a query language with the desired properties (over finite and infinite RDF graphs). It should be noticed that every query in this fragment is weakly monotone if we restrict to the case of finite RDF graphs. Moreover, we use this result to provide a simple characterization of the class of monotone CONSTRUCT queries, that is, the class of SPARQL queries that produce RDF graphs as output. Finally, we pinpoint the complex-

show abstract

Algebraic Structures for Capturing the Provenance of SPARQL Queries

Cited by 30 publications

References 30 publications

Explaining Axiom Pinpointing

Explaining Axiom Pinpointing

Complexity and Expressive Power of Weakly Well-Designed SPARQL

Designing a Query Language for RDF

Contact Info

Product

Resources

About