Containment of Simple Conjunctive Regular Path Queries

2020 ◽  
Author(s):  
Diego Figueira ◽  
Adwait Godbole ◽  
S. Krishna ◽  
Wim Martens ◽  
Matthias Niewerth ◽  
...  
Keyword(s):  
Knowledge Representation ◽  
Query Language ◽  
Regular Expressions ◽  
Graph Database ◽  
Reasoning Task ◽  
Containment Problem ◽  
Database Querying ◽  
Regular Path ◽  
Regular Path Queries ◽  
Path Queries

Testing containment of queries is a fundamental reasoning task in knowledge representation. We study here the containment problem for Conjunctive Regular Path Queries (CRPQs), a navigational query language extensively used in ontology and graph database querying. While it is known that containment of CRPQs is EXPSPACE-complete in general, we focus here on severely restricted fragments, which are known to be highly relevant in practice according to several recent studies. We obtain a detailed overview of the complexity of the containment problem, depending on the features used in the regular expressions of the queries, with completeness results for NP, Pi2p, PSPACE or EXPSPACE.

scholarly journals Rewriting of Regular Expressions and Regular Path Queries

2002 ◽  
Vol 64 (3) ◽  
pp. 443-465 ◽  
Author(s):  
Diego Calvanese ◽  
Giuseppe De Giacomo ◽  
Maurizio Lenzerini ◽  
Moshe Y. Vardi
Keyword(s):  
Regular Expressions ◽  
Regular Path ◽  
Regular Path Queries ◽  
Path Queries

scholarly journals Regular Path Queries in Lightweight Description Logics: Complexity and Algorithms

2015 ◽  
Vol 53 ◽  
pp. 315-374 ◽  
Author(s):  
Meghyn Bienvenu ◽  
Magdalena Ortiz ◽  
Mantas Simkus
Keyword(s):  
Description Logic ◽  
Query Language ◽  
Description Logics ◽  
Knowledge Bases ◽  
Query Answering ◽  
Complexity Bounds ◽  
Regular Path ◽  
Regular Path Queries ◽  
Path Navigation ◽  
Path Queries

Conjunctive regular path queries are an expressive extension of the well-known class of conjunctive queries. Such queries have been extensively studied in the (graph) database community, since they support a controlled form of recursion and enable sophisticated path navigation. Somewhat surprisingly, there has been little work aimed at using such queries in the context of description logic (DL) knowledge bases, particularly for the lightweight DLs that are considered best suited for data-intensive applications. This paper aims to bridge this gap by providing algorithms and tight complexity bounds for answering two-way conjunctive regular path queries over DL knowledge bases formulated in lightweight DLs of the DL-Lite and EL families. Our results demonstrate that in data complexity, the cost of moving to this richer query language is as low as one could wish for: the problem is NL-complete for DL-Lite and P-complete for EL. The combined complexity of query answering increases from NP- to PSpace-complete, but for two-way regular path queries (without conjunction), we show that query answering is tractable even with respect to combined complexity. Our results reveal two-way conjunctive regular path queries as a promising language for querying data enriched by ontologies formulated in DLs of the DL-Lite and EL families or the corresponding OWL 2 QL and EL profiles.

PAIRPQ: An Efficient Path Index for Regular Path Queries on Knowledge Graphs

2021 ◽  
pp. 106-120
Author(s):  
Baozhu Liu ◽  
Xin Wang ◽  
Pengkai Liu ◽  
Sizhuo Li ◽  
Xiaofei Wang
Keyword(s):  
Path Index ◽  
Regular Path ◽  
Regular Path Queries ◽  
Knowledge Graphs ◽  
Path Queries

scholarly journals Algebraic rewritings for optimizing regular path queries

2003 ◽  
Vol 296 (3) ◽  
pp. 453-471 ◽  
Author(s):  
Gösta Grahne ◽  
Alex Thomo
Keyword(s):  
Regular Path ◽  
Regular Path Queries ◽  
Path Queries

scholarly journals Regular Path Queries with Constraints

1999 ◽  
Vol 58 (3) ◽  
pp. 428-452 ◽  
Author(s):  
Serge Abiteboul ◽  
Victor Vianu
Keyword(s):  
Regular Path ◽  
Regular Path Queries ◽  
Path Queries
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