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ICCL Summer School 2013  -   Course Program

Ontology-based Model Checking Applications

Uwe Aßmann    (Technische Universität Dresden, Germany)

Ontology services can be called from standard software to check constraints or calculate the subsumption of certain concepts. If appropriate transformations from arbitrary specifications or models to ontologies are defined, they can provide a powerful backend tool for constraint checking of these specifications. The course discusses several prerequisites, such as model-driven software development in general, the notion of a technical space and the bridges between them. Then it presents several examples for using the ontology services as backends of specification tools, such as consistency checking for product line models (feature models), safety models, and domain-specific languages.

Here are the slides: assmann-1-odsd.pdf, assmann-2-logic-domain-specific-languages.pdf, assmann-OWLText.zip, assmann-ADOxx_PDDSL-Tool.zip

Reasoning in Expressive Description Logics

Franz Baader    (Technische Universität Dresden, Germany)

Description Logics (DLs) are a successful family of logic-based knowledge representation formalisms, which can be used to represent the conceptual knowledge of an application domain in a structured and formally well-understood way. They are employed in various application domains, such as natural language processing, configuration, and databases, but their most notable success so far is the adoption of the DL-based language OWL DL as standard ontology language for the semantic web.
This tutorial concentrates on designing and analyzing reasoning procedures for expressive DLs. After a short introduction and a brief overview of the research of the last 20 years, it will present approaches for reasoning in expressive DLs, which are the foundation for reasoning in OWL DL. In particular, it will introduce tableau-based and automata-based reasoning procedures and will analyze the computational complexity of reasoning in DLs.

The exact slides of this course are not available.
But you may have look at the slides at the bottom of this page

Datalog-Based Data Access over Ontology Knowledge Bases

Thomas Eiter    (Technische Universität Wien, Austria)

Querying ontological knowledge bases to elicit information about individuals has received growing attention in the last years, leading to new research directions. The issue is closely related to combining rules and ontologies, given that prominent kinds of queries can be viewed as (often simple) rules. In databases, Datalog is a well-established query language that is a core fragment of logic programming with recursion, for which several effective reasoning engines have been provided, some of them also supporting unstratified negation. In this course, we address query answering over ontologies based on Datalog as host language. We survey combinations of rules an ontologies for query answering, and focus on loose coupling that uses query interfaces to ontologies to facilitate rules on top of ontologies. We then consider particular query types, instance and conjunctive queries, which for various description logics have been reduced to Datalog, among them ones underlying the OWL 2 Profiles, and may be exploited in more expressive query interfaces. Besides theoretical foundations, we also consider some system developments. The learning outcome of this course should be awareness of Datalog reduction approaches, benefits and limitations of those, and knowledge of some systems that have been under development.

Here are corrected slides: unit0, unit1, unit2, unit3, unit4

Linked Data Applications at fluidOps

Peter Haase    (fluid Operations AG, Germany)

In this lecture, we present practical applications of Linked Data and semantic technologies in the enterprise. We will cover fundamantel concepts of building Linked Data applications as well as concrete example solutions in domains such as data center management, energy and social media,. We will illustrate these concepts based on the Information Workbench, a platform for Linked Data in the enterprise. Particular focus will be on practical uses of Ontology-based Data Access to enable scalable end-user access to Big Data.

Here are the slides: iccl_haase_1, iccl_haase_2

Ontologies and Rules

Pascal Hitzler    (Wright State University, Dayton, Ohio, U. S. A.)

The relationship between the Web Ontology Language OWL and rule-based formalisms such as Datalog and RIF has been the subject of many discussions and research investigations, some of them controversial. From the many attempts to reconcile the two paradigms, we present some of the newest developments. More precisely, we show which kind of rules can be modeled in the current version of OWL, and we show how OWL can be extended to incorporate rules without compromising OWL design principles. The course also includes a discussion of the fundamental limitations concering the integration of OWL and Rules, and a report on ongoing work regarding algorithmizations of reasoning for our integrated paradigm.

Here are the slides:
2013-08-ICCLSS-intro.pdf, 2013-08-ICCLSS-ont+rules.pdf, 2013-08-ICCLSS-owl+rdf.pdf, 2013-08-ICCLSS-patterns.pdf

Geosemantics, Linked Spatiotemporal Data, and Geo-Ontologies

Krzysztof Janowicz    (University of California, Santa Barbara, U. S. A.)

The course will introduce students to the field of Geospatial Semantics. It will cover a brief history of the field, introduce major research challenges, familiarize the students with sources of Linked Spatiotemporal Data, and discuss some well known Geo-Ontologies. The course will be driven by concrete application areas and use cases. The added value of semantic technologies and ontologies will be discussed. Students will learn why semantic heterogeneity is an essential part of interdisciplinary science and discuss methods how to approach it. In addition to aspects of knowledge representation and reasoning, the course will also focus on user interfaces and user interaction paradigms. Finally, the course will point out open questions and close with a broader perspective on the role of semantic technologies for workflows in science. The content of the class will be presented in a series of short interactive lectures followed by discussions and group task for the students.

Here are the slides: session1, session2, session3, session4

Towards a Semantic Web Unifying Logic

Matthias Knorr    (Universidade Nova de Lisboa, Portugal)

Building on the contents presented on ontologies and rules, the course focuses on how to overcome one of the major conceptual differences between the two W3C standards OWL and RIF, namely, the first-order Open World Assumption of the former vs. the non-monotonic Closed World Assumption of the latter. We propose and discuss a description logic extending SROIQ (the description logic underlying OWL 2 DL) and at the same time encompassing some of the most prominent monotonic and non-monotonic rule languages, in particular Datalog extended with the answer set semantics. To this end, we are also going to consider combinations of non-monotonic rules and Description Logics in more detail. We argue that our proposal could be considered a substantial contribution towards fulfilling the quest for a unifying logic for the Semantic Web.

Here are the slides: iccl-knorr.pdf

Rule-Based Reasoning in Lightweight Ontology Languages

Markus Krötzsch    (University of Oxford, U. K.)

This lecture gives an extended introduction to lightweight ontology languages, in particular to the OWL EL and OWL RL profiles of the Web Ontology Language OWL. The OWL profiles are sublanguages of the OWL DL standard that are restricted in ways that significantly simplify ontological reasoning. Compared to OWL DL as a whole, reasoning algorithms for the OWL profiles show higher performance, are easier to implement, and can scale to larger amounts of data. Since ontological reasoning is of great importance for designing and deploying OWL ontologies, the profiles are highly attractive for many applications. These advantages come at a price: various modelling features of OWL are not available in all or some of the OWL profiles. This chapter provides an overview of these differences and explains why some of them are essential to retain the desired properties. To this end, we recall the relationship between OWL and description logics (DLs), and show how each of the profiles is typically treated in reasoning algorithms, with a particular focus on rule-based reasoning procedures.

Here are the slides: Kroetzsch-ICCL-summer-school.pdf

The Linked Data Lifecycle

Jens Lehmann    (University of Leipzig, Germany)

With Linked Data, a very pragmatic approach towards achieving the vision of the Semantic Web gained much traction. While many standards, methods and technologies developed within the Semantic Web activity are applicable for Linked Data, there are also a number of specific characteristics of Linked Data, which have to be considered. We introduce the main concepts of Linked Data and present an overview of its life-cycle. We discuss individual approaches as well as the state-of-the-art with regard to extraction, storage and querying, authoring, linking, enrichment, quality analysis, as well as search and exploration of Linked Data. We conclude the article with a discussion of issues, limitations and further research and development challenges of Linked Data.

Here are the slides: lehmann-ld-lifecycle.pdf

RDF and SPARQL

Sebastian Rudolph    (Technische Universität Dresden, Germany)

The Resource Description Framework RDF is a formal language for describing structured information. The goal of RDF is to enable applications to exchange data on the Web while still preserving their original meaning. RDF consequently is often viewed as the basic representation format for developing the Semantic Web. In the lecture, we will introduce the basic, graph-based data model underlying RDF and explain its syntax. We show how complex data structures (n-ary relations, lists, etc.) can be captured by the very simple RDF data model. Next, we introduce RDF Schema, which enriches the fact-based modelling of RDF by ways to specify terminological knowledge. We then provide a model-theoretic, formal semantics for RDF and RDF Schema and show how to perform inferencing efficiently based on a deduction calculus. Thereafter we introduce SPARQL, a query language for RDF data, featuring graph patterns, filters, as well as modifiers for the output. We describe the syntax of SPARQL in detail and then provide its semantics which, just like the semantics of SQL, is defined in an algebraic way. Concluding, we discuss some engineering aspects and application scenarios related to RDF and SPARQL.

Here are the slides:
1_RDF.pdf, 2_RDFS.pdf, 3_RDF-Semantics.pdf, 4_SPARQL-Syntax.pdf, 5_SPARQL-Semantics.pdf

Workshop Presentations

The workshop consists of short presentations about the research work of selected participants.