Ontological Query Answering over Semantic Data

2017 ◽  
pp. 29-63
Author(s):  
Giorgos Stamou ◽  
Alexandros Chortaras
Keyword(s):  
Query Answering ◽  
Semantic Data

Cooperative Query Processing via Knowledge Abstraction and Query Relaxation

2002 ◽  
pp. 211-228 ◽  
Author(s):  
Soon-Young Huh ◽  
Kae-Hyun Moon ◽  
Jin-Kyun Ahn
Keyword(s):  
Query Language ◽  
Database Systems ◽  
Query Answering ◽  
Prototype System ◽  
Levels Of Abstraction ◽  
Semantic Data ◽  
Approximate Query Answering ◽  
Approximate Query ◽  
Approximate Answers ◽  
General Fact

As database users adopt a query language to obtain information from a database, a more intelligent query answering system is increasingly needed that cooperates with the users to provide informative responses by understanding the intent behind a query. The effectiveness of decision support would improve significantly if the query answering system returned approximate answers rather than a null information response when there is no matching data available. Even when exact answers are found, neighboring information is still useful to users if the query is intended to explore some hypothetical information or abstract general fact. This chapter proposes an abstraction hierarchy as a framework to practically derive such approximate answers from ordinary everyday databases. It provides a knowledge abstraction database to facilitate the approximate query answering. The knowledge abstraction database specifically adopts an abstraction approach to extract semantic data relationships from the underlying database, and uses a multi-level hierarchy for coupling multiple levels of abstraction knowledge and data values. In cooperation with the underlying database, the knowledge abstraction database allows the relaxation of query conditions so that the original query scope can be broadened and thus information approximate to exact answers can be obtained. Conceptually abstract queries can also be posed to provide a less rigid query interface. A prototype system has been implemented at KAIST and is being tested with a personnel database system to demonstrate the usefulness and practicality of the knowledge abstraction database in ordinary database systems.

Computing Cores for Existential Rules with the Standard Chase and ASP

2020 ◽  
Author(s):  
Markus Krötzsch
Keyword(s):  
Large Class ◽  
Data Exchange ◽  
Answer Set Programming ◽  
Query Answering ◽  
Universal Model ◽  
The Core ◽  
Universal Models ◽  
General Terms ◽  
Special Cases ◽  
The Many

To reason with existential rules (a.k.a. tuple-generating dependencies), one often computes universal models. Among the many such models of different structure and cardinality, the core is arguably the “best”. Especially for finitely satisfiable theories, where the core is the unique smallest universal model, it has advantages in query answering, non-monotonic reasoning, and data exchange. Unfortunately, computing cores is difficult and not supported by most reasoners. We therefore propose ways of computing cores using practically implemented methods from rule reasoning and answer set programming. Our focus is on cases where the standard chase algorithm produces a core. We characterise this desirable situation in general terms that apply to a large class of cores, derive concrete approaches for decidable special cases, and generalise these approaches to non-monotonic extensions of existential rules.

scholarly journals BIM-Integrated Collaborative Robotics for Application in Building Construction and Maintenance

Robotics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 2
Author(s):  
Camilla Follini ◽  
Valerio Magnago ◽  
Kilian Freitag ◽  
Michael Terzer ◽  
Carmen Marcher ◽  
...  
Keyword(s):  
Semantic Information ◽  
Building Information Modeling ◽  
A Priori ◽  
Building Construction ◽  
Information Modeling ◽  
Robotic Systems ◽  
Design Phase ◽  
Collaborative Robotics ◽  
Semantic Data ◽  
Building Information

The application of robotics in construction is hindered by the site environment, which is unstructured and subject to change. At the same time, however, buildings and corresponding sites can be accurately described by Building Information Modeling (BIM). Such a model contains geometric and semantic data about the construction and operation phases of the building and it is already available at the design phase. We propose a method to leverage BIM for simple yet efficient deployment of robotic systems for construction and operation of buildings. With our proposed approach, BIM is used to provide the robot with a priori geometric and semantic information on the environment and to store information on the operation progress. We present two applications that verify the effectiveness of our proposed method. This system represents a step forward towards an easier application of robots in construction.

An Improved Set-based Reasoner for the Description Logic 𝒟ℒD4,׆

2021 ◽  
Vol 178 (4) ◽  
pp. 315-346
Author(s):  
Domenico Cantone ◽  
Marianna Nicolosi-Asmundo ◽  
Daniele Francesco Santamaria
Keyword(s):  
Semantic Web ◽  
Set Theory ◽  
Description Logic ◽  
Knowledge Bases ◽  
Query Answering ◽  
Conjunctive Query ◽  
Classification Problems ◽  
Previous Version ◽  
Decidable Fragment ◽  
Stratified Set

We present a KE-tableau-based implementation of a reasoner for a decidable fragment of (stratified) set theory expressing the description logic 𝒟ℒ〈4LQSR,×〉(D) (𝒟ℒD4,×, for short). Our application solves the main TBox and ABox reasoning problems for 𝒟ℒD4,×. In particular, it solves the consistency and the classification problems for 𝒟ℒD4,×-knowledge bases represented in set-theoretic terms, and a generalization of the Conjunctive Query Answering problem in which conjunctive queries with variables of three sorts are admitted. The reasoner, which extends and improves a previous version, is implemented in C++. It supports 𝒟ℒD4,×-knowledge bases serialized in the OWL/XML format and it admits also rules expressed in SWRL (Semantic Web Rule Language).

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