291 research outputs found
Automatic Generation of Personalized Recommendations in eCoaching
Denne avhandlingen omhandler eCoaching for personlig livsstilsstøtte i sanntid ved bruk av informasjons- og kommunikasjonsteknologi. Utfordringen er å designe, utvikle og teknisk evaluere en prototyp av en intelligent eCoach som automatisk genererer personlige og evidensbaserte anbefalinger til en bedre livsstil. Den utviklede løsningen er fokusert på forbedring av fysisk aktivitet. Prototypen bruker bærbare medisinske aktivitetssensorer. De innsamlede data blir semantisk representert og kunstig intelligente algoritmer genererer automatisk meningsfulle, personlige og kontekstbaserte anbefalinger for mindre stillesittende tid. Oppgaven bruker den veletablerte designvitenskapelige forskningsmetodikken for å utvikle teoretiske grunnlag og praktiske implementeringer. Samlet sett fokuserer denne forskningen på teknologisk verifisering snarere enn klinisk evaluering.publishedVersio
The Complexity of Fuzzy Description Logics over Finite Lattices with Nominals
The complexity of reasoning in fuzzy description logics (DLs) over finite lattices usually does not exceed that of the underlying classical DLs. This has recently been shown for the logics between L-IALC and L-ISCHI using a combination of automata- and tableau-based techniques. In this report, this approach is modified to deal with nominals and constants in L-ISCHOI. Reasoning w.r.t. general TBoxes is ExpTime-complete, and PSpace-completeness is shown under the restriction to acyclic terminologies in two sublogics. The latter implies two previously unknown complexity results for the classical DLs ALCHO and SO
Inspecting Java Program States with Semantic Web Technologies
Semantic debugging, as introduced by Kamburjan et al., refers to the practice of applying technologies of the semantic web to query the run-time state of a program and combine it with external domain knowledge.
This master thesis aims to take the first step toward making the benefits of semantic debugging available for real-world application development.
For this purpose, we implement a semantic debugging tool for the Java programming language, called the Semantic Java Debugger or sjdb.
The sjdb tool provides an interactive, command line-based user interface through which users can (1) run Java programs and suspend their execution at user-defined breakpoints, (2) automatically extract RDF knowledge bases with description logic semantics that describe the current state of the program, (3) optionally supplement the knowledge base with external domain knowledge formalized in OWL, (4) run (semantic) queries on this extended knowledge base, and resolve the query results back to Java objects.
As part of this debugging tool, the development of an extraction mechanism for knowledge bases from the states of suspended Java programs is one of the main contributions of this thesis. For this purpose, we also devise an OWL formalization of Java runtime states to structure this extraction process and give meaning to the resulting knowledge base.
Moreover, case studies are conducted to demonstrate the capabilities of sjdb, but also to identify its limitations, as well as its response times and memory requirements
LTL over EL Axioms
Aus der Einleitung:
Description Logics (DLs) [BCM+07] are popular knowledge representation formalisms, mainly because they are the basis of the standardized OWL 2 Direct Semantics, their expressiveness can be tailored to the application at hand, and many optimized reasoning systems are available
First-Order Rewritability and Complexity of Two-Dimensional Temporal Ontology-Mediated Queries
Aiming at ontology-based data access to temporal data, we design
two-dimensional temporal ontology and query languages by combining logics from
the (extended) DL-Lite family with linear temporal logic LTL over discrete time
(Z,<). Our main concern is first-order rewritability of ontology-mediated
queries (OMQs) that consist of a 2D ontology and a positive temporal instance
query. Our target languages for FO-rewritings are two-sorted FO(<) -
first-order logic with sorts for time instants ordered by the built-in
precedence relation < and for the domain of individuals - its extension FOE
with the standard congruence predicates t \equiv 0 mod n, for any fixed n > 1,
and FO(RPR) that admits relational primitive recursion. In terms of circuit
complexity, FOE- and FO(RPR)-rewritability guarantee answering OMQs in uniform
AC0 and NC1, respectively.
We proceed in three steps. First, we define a hierarchy of 2D DL-Lite/LTL
ontology languages and investigate the FO-rewritability of OMQs with atomic
queries by constructing projections onto 1D LTL OMQs and employing recent
results on the FO-rewritability of propositional LTL OMQs. As the projections
involve deciding consistency of ontologies and data, we also consider the
consistency problem for our languages. While the undecidability of consistency
for 2D ontology languages with expressive Boolean role inclusions might be
expected, we also show that, rather surprisingly, the restriction to Krom and
Horn role inclusions leads to decidability (and ExpSpace-completeness), even if
one admits full Booleans on concepts. As a final step, we lift some of the
rewritability results for atomic OMQs to OMQs with expressive positive temporal
instance queries. The lifting results are based on an in-depth study of the
canonical models and only concern Horn ontologies
Integrate Action Formalisms into Linear Temporal Description Logics
The verification problem for action logic programs with non-terminating behaviour is in general undecidable. In this paper, we consider a restricted setting in which the problem becomes decidable. On the one hand, we abstract from the actual execution sequences of a non-terminating program by considering infinite sequences of actions defined by a BĂĽchi automaton. On the other hand, we assume that the logic underlying our action formalism is a decidable description logic rather than full first-order predicate logic
A Tableau Algorithm for SROIQ under Infinitely Valued Gödel Semantics
Fuzzy description logics (FDLs) are knowledge representation formalisms capable of dealing with imprecise knowledge by allowing intermediate membership degrees in the interpretation of concepts and roles. One option for dealing with these intermediate degrees is to use the so-called Gödel semantics. Despite its apparent simplicity, developing reasoning techniques for expressive FDLs under this semantics is a hard task. We present a tableau algorithm for deciding consistency of a SROIQ ontology under Gödel semantics. This is the first algorithm that can handle the full expressivity of SROIQ as well as the full Gödel semantics
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