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Chapter and Conference Paper
Nested Regular Expressions Can Be Compiled to Small Deterministic Nested Word Automata
We study the problem of whether regular expressions for nested words can be compiled to small deterministic nested word automata (NWAs). In theory, we obtain a positive answer for small deterministic regular expr...
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Chapter and Conference Paper
Consistency and Certain Answers in Relational to RDF Data Exchange with Shape Constraints
We investigate the data exchange from relational databases to RDF graphs inspired by R2RML with the addition of target shape schemas capturing fragments of SHACL and ShEx. We study the problems of consistency i.e...
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Chapter and Conference Paper
Regular Matching and Inclusion on Compressed Tree Patterns with Context Variables
We study the complexity of regular matching and inclusion for compressed tree patterns extended by context variables. The addition of context variables to tree patterns permits us to properly capture compresse...
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Chapter
The RDF Ecosystem
This chapter includes a short overview of the RDF data model and the Turtle notation, as well as some technologies like SPARQL, RDF Schema, and OWL that form part of the RDF ecosystem.
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Chapter
Introduction
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Chapter and Conference Paper
Certain Query Answering on Compressed String Patterns: From Streams to Hyperstreams
We study the problem of certain query answering (Cqa) on compressed string patterns. These are incomplete singleton context-free grammars, that can model systems of multiple streams with references to others, cal...
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Chapter
Shape Expressions
Shape Expressions (ShEx) is a schema language for describing RDF graphs structures. ShEx was originally developed in late 2013 to provide a human-readable syntax for OSLC Resource Shapes. It added disjunctions...
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Chapter
Applications
In this chapter we describe several applications of RDF validation. We start with the WebIndex, a medium-size linked data portal that was one of the earliest applications of ShEx. We describe it using ShEx and...
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Book
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Chapter
Data Quality
People have been using computers to record and reason about data for many decades. Typically, this reasoning is less esoteric than artificial intelligence tasks like classification.
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Chapter
SHACL
Shapes Constraint Language (SHACL) has been developed by the W3C RDF Data Shapes Working Group, which was chartered in 2014 with the goal to “produce a language for defining structural constraints on RDF graph...
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Chapter
Comparing ShEx and SHACL
In this chapter we present a comparison between ShEx and SHACL. The technologies have similar goals and similar features. In fact at the start of the Data Shapes Working Group in 2014, convergence on a unified...
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Chapter and Conference Paper
Semantics and Validation of Shapes Schemas for RDF
We present a formal semantics and proof of soundness for shapes schemas, an expressive schema language for RDF graphs that is the foundation of Shape Expressions Language 2.0. It can be used to describe the vo...
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Article
Schemas for Unordered XML on a DIME
We investigate schema languages for unordered XML having no relative order among siblings. First, we propose unordered regular expressions (UREs), essentially regular expressions with unordered concatenation inst...
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Chapter and Conference Paper
Generation of Sierpinski Triangles: A Case Study for Graph Transformation Tools
In this paper, we consider a large variety of solutions for the generation of Sierpinski triangles, one of the case studies for the AGTIVE graph transformation tool contest [15]. A Sierpinski triangle shows a ...
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Chapter and Conference Paper
A Modal-Logic Based Graph Abstraction
Infinite or very large state spaces often prohibit the successful verification of graph transformation systems. Abstract graph transformation is an approach that tackles this problem by abstracting graphs to a...
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Chapter and Conference Paper
Automata and Logics for Unranked and Unordered Trees
In this paper, we consider the monadic second order logic (MSO) and two of its extensions, namely Counting MSO (CMSO) and Presburger MSO (PMSO), interpreted over unranked and unordered trees. We survey classes...
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Chapter and Conference Paper
On Complexity of Model-Checking for the TQL Logic
In this paper we study the complexity of the model-checking problem for the tree logic introduced as the basis for the query language TQL [Cardelli and Ghelli, 2001]. We define two distinct fragments of this l...
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Chapter and Conference Paper
When Ambients Cannot Be Opened
We investigate expressiveness of a fragment of the ambient calculus, a formalism for describing distributed and mobile computations. More precisely, we study expressiveness of the pure and public ambient calcu...
