Consistency and Certain Answers in Relational to RDF Data Exchange with Shape Constraints

03/30/2020
by   Iovka Boneva, et al.
0

We investigate the data exchange from relational databases to RDF graphs inspired by R2RML with the addition of target shape schemas. We study the problems of consistency i.e., checking that every source instance admits a solution, and certain query answering i.e., finding answers present in every solution. We identify the class of constructive relational to RDF data exchange that uses IRI constructors and full tgds (with no existential variables) in its source to target dependencies. We show that the consistency problem is coNP-complete. We introduce the notion of universal simulation solution that allows to compute certain query answers to any class of queries that is robust under simulation. One such class are nested regular expressions (NREs) that are forward i.e., do not use the inverse operation. Using universal simulation solution renders tractable the computation of certain answers to forward NREs (data-complexity). Finally, we present a number of results that show that relaxing the restrictions of the proposed framework leads to an increase in complexity.

READ FULL TEXT
POST COMMENT

Comments

There are no comments yet.

Authors

page 1

page 2

page 3

page 4

04/30/2018

Relational to RDF Data Exchange in Presence of a Shape Expression Schema

We study the relational to RDF data exchange problem, where the tar- get...
01/19/2018

Computing Possible and Certain Answers over Order-Incomplete Data

This paper studies the complexity of query evaluation for databases whos...
12/16/2021

Computing the Shapley Value of Facts in Query Answering

The Shapley value is a game-theoretic notion for wealth distribution tha...
08/25/2020

On the complexity of query containment and computing certain answers in the presence of ACs

We often add arithmetic to extend the expressiveness of query languages ...
06/06/2016

Consistency and Trust in Peer Data Exchange Systems

We propose and investigate a semantics for "peer data exchange systems" ...
03/30/2019

Uncertainty Annotated Databases - A Lightweight Approach for Approximating Certain Answers (extended version)

Certain answers are a principled method for coping with uncertainty that...
03/04/2019

A Simple Solution to the Level-Ancestor Problem

A Level Ancestory query LA(u, d) asks for the the ancestor of the node u...
This week in AI

Get the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday.