584 research outputs found
A Provenance Tracking Model for Data Updates
For data-centric systems, provenance tracking is particularly important when
the system is open and decentralised, such as the Web of Linked Data. In this
paper, a concise but expressive calculus which models data updates is
presented. The calculus is used to provide an operational semantics for a
system where data and updates interact concurrently. The operational semantics
of the calculus also tracks the provenance of data with respect to updates.
This provides a new formal semantics extending provenance diagrams which takes
into account the execution of processes in a concurrent setting. Moreover, a
sound and complete model for the calculus based on ideals of series-parallel
DAGs is provided. The notion of provenance introduced can be used as a
subjective indicator of the quality of data in concurrent interacting systems.Comment: In Proceedings FOCLASA 2012, arXiv:1208.432
Relative Expressive Power of Navigational Querying on Graphs
Motivated by both established and new applications, we study navigational
query languages for graphs (binary relations). The simplest language has only
the two operators union and composition, together with the identity relation.
We make more powerful languages by adding any of the following operators:
intersection; set difference; projection; coprojection; converse; and the
diversity relation. All these operators map binary relations to binary
relations. We compare the expressive power of all resulting languages. We do
this not only for general path queries (queries where the result may be any
binary relation) but also for boolean or yes/no queries (expressed by the
nonemptiness of an expression). For both cases, we present the complete Hasse
diagram of relative expressiveness. In particular the Hasse diagram for boolean
queries contains some nontrivial separations and a few surprising collapses.Comment: An extended abstract announcing the results of this paper was
presented at the 14th International Conference on Database Theory, Uppsala,
Sweden, March 201
Iteration Algebras for UnQL Graphs and Completeness for Bisimulation
This paper shows an application of Bloom and Esik's iteration algebras to
model graph data in a graph database query language. About twenty years ago,
Buneman et al. developed a graph database query language UnQL on the top of a
functional meta-language UnCAL for describing and manipulating graphs.
Recently, the functional programming community has shown renewed interest in
UnCAL, because it provides an efficient graph transformation language which is
useful for various applications, such as bidirectional computation. However, no
mathematical semantics of UnQL/UnCAL graphs has been developed. In this paper,
we give an equational axiomatisation and algebraic semantics of UnCAL graphs.
The main result of this paper is to prove that completeness of our equational
axioms for UnCAL for the original bisimulation of UnCAL graphs via iteration
algebras. Another benefit of algebraic semantics is a clean characterisation of
structural recursion on graphs using free iteration algebra.Comment: In Proceedings FICS 2015, arXiv:1509.0282
An annotation database for multimodal scientific data
Cristina Bogdanschi, Simone Santini, "An annotation database for multimodal scientific data", Proc. SPIE 7255, Multimedia Content Access: Algorithms and Systems III, 72550G (2009). Copyright 2009 Society of Photo‑Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.In many collaborative research environments novel tools and techniques allow researchers to generate data from experiments and observations at a staggering rate. Researchers in these areas are now facing the strong need for querying, sharing and exchanging these data in a uniform and transparent fashion. However, due to the nature of the various types of heterogeneous data and lack of local and global database structures, standard data integration approaches fail or are not applicable. A viable solution to this problem is the extensive use of metadata. In this paper we present the model of an annotation management system suitable for such research environments, and discuss some aspects of its implementation. Annotations provide rich linkage structure between data and between themselves that translates in a complex graph structure of which annotations and data are the nodes. We show how annotations are managed and used for data retrieval and outline some of the query techniques used in the system
CrocoPat 2.1 Introduction and Reference Manual
CrocoPat is an efficient, powerful and easy-to-use tool for manipulating
relations of arbitrary arity, including directed graphs. This manual provides
an introduction to and a reference for CrocoPat and its programming language
RML. It includes several application examples, in particular from the analysis
of structural models of software systems.Comment: 19 pages + cover, 2 eps figures, uses llncs.cls and
cs_techrpt_cover.sty, for downloading the source code, binaries, and RML
examples, see http://www.software-systemtechnik.de/CrocoPat
A Researcher’s Digest of GQL
International audienceGQL (Graph Query Language) is being developed as a new ISO standard for graph query languages to play the same role for graph databases as SQL plays for relational. In parallel, an extension of SQL for querying property graphs, SQL/PGQ, is added to the SQL standard; it shares the graph pattern matching functionality with GQL. Both standards (not yet published) are hard-to-understand specifications of hundreds of pages. The goal of this paper is to present a digest of the language that is easy for the research community to understand, and thus to initiate research on these future standards for querying graphs. The paper concentrates on pattern matching features shared by GQL and SQL/PGQ, as well as querying facilities of GQL
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