Работа с онтологической моделью организации на основе дескриптивной логики

Рассмотрена последовательность преобразований онтологической модели в модель дескриптивной логики с применением системы логического вывода. В качестве системы поддержки работы с моделью дескриптивной логики используется система логического вывода RACER. Приводится способ проверки правильности онтологии на основе доказательства запроса на выполнимость модели дескриптивной логики

OWL Reasoners still useable in 2023

In a systematic literature and software review over 100 OWL reasoners/systems were analyzed to see if they would still be usable in 2023. This has never been done in this capacity. OWL reasoners still play an important role in knowledge organisation and management, but the last comprehensive surveys/studies are more than 8 years old. The result of this work is a comprehensive list of 95 standalone OWL reasoners and systems using an OWL reasoner. For each item, information on project pages, source code repositories and related documentation was gathered. The raw research data is provided in a Github repository for anyone to use

Federated description logics for the semantic web

The thesis deals with a family of federated description logics for creating modular ontologies in the semantic web. All these logics share modularity, the possibility to reuse concept names and role names by importing, and context-sensitive interpretation of all logical connectives. Apart from the main basic language F-ALCI, we present a lattice-based extension LF-ALCI, a probabilistic extension PF-ALCI and an extension that employs knowledge operators F-ALCIK. All languages are based on the ordinary well-known description logic ALCI

Sistemas de pergunta-resposta para a Web semântica

O aumento significativo de informação não estruturada e heterogénea, disponível na web, e a necessidade no acesso em tempo real promovem o desenvolvimento de ferramentas, capazes de "dialogar" com o utilizador e que respondam de forma eficaz às suas exigências. O foco desta tese está no desenvolvimento de um sistema cooperativo de Pergunta-Resposta para a Web Semântica. As principais contribuições consistem no enriquecimento do sistema com um Controlador do Discurso que, através da análise e da representação semântica da questão, do tipo de resposta esperada, e da estrutura do discurso, permite fornecer respostas objetivas, informativas e justificadas. Acrescido de capacidades cooperativas, capacidade de interação com o utilizador, o sistema obtém informação necessária para esclarecer ambiguidades e conduzi-lo no caminho para a resposta correta. O desempenho do sistema é avaliado por comparação com outros sistemas semelhantes. Embora o conjunto de testes seja de pequena dimensão, os resultados obtidos são bastante promissores; ### Question Answering for the Semantic Web Abstract: The significant increase of unstructured and heterogeneous information, available on the web, and the need of real-time access promote the development of engines able to \dialogue" with the user and to answer effectively to their requirements. The focus of this thesis is in the development of a cooperative Question-Answering system for the Semantic Web. The main contributions consist in enriching the system with a Discourse Controller that, through the analysis and the semantic representation of the question, the type of expected answer and the structure of the discourse, can provide accurate, informative and justified answers. Increased with cooperative skills, ability to interact with the user, the system obtains information necessary to clarify ambiguities and lead on the path to the correct answer. The system performance is evaluated by comparing with similar question answering systems. Although the test suite has slight dimensions, the results obtained are very promising

Investigation of the tradeoff between expressiveness and complexity in description logics with spatial operators

Le Logiche Descrittive sono una famiglia di formalismi molto espressivi per la rappresentazione della conoscenza. Questi formalismi sono stati investigati a fondo dalla comunit\ue0 scientifica, ma, nonostante questo grosso interesse, sono state definite poche Description Logics con operatori spaziali e tutte centrate sul Region Connection Calculus. Nella mia tesi considero tutti i pi\uf9 importanti formalismi di Qualitative Spatial Reasoning per mereologie, mereo-topologie e informazioni sulla direzione e studio alcune tecniche generali di ibridazione. Nella tesi presento un\u2019introduzione ai principali formalismi di Qualitative Spatial Reasoning e le principali famiglie di Description Logics. Nel mio lavoro, introduco anche le tecniche di ibridazione per estendere le Description Logics al ragionamento su conoscenza spaziale e presento il potere espressivo dei linguaggi ibridi ottenuti. Vengono presentati infine un risultato generale di para-decidibilit\ue0 per logiche descrittive estese da composition-based role axioms e l\u2019analisi del tradeoff tra espressivit\ue0 e propriet\ue0 computazionali delle logiche descrittive spaziali.Description Logics are a family of expressive Knowledge-Representation formalisms that have been deeply investigated. Nevertheless the few examples of DLs with spatial operators in the current literature are defined to include only the spatial reasoning capabilities corresponding to the Region Connection Calculus. In my thesis I consider all the most important Qualitative Spatial Reasoning formalisms for mereological, mereo-topological and directional information and investigate some general hybridization techniques. I will present a short overview of the main formalisms of Qualitative Spatial Reasoning and the principal families of DLs. I introduce the hybridization techniques to extend DLs to QSR and present the expressiveness of the resulting hybrid languages. I also present a general paradecidability result for undecidable languages equipped with composition-based role axioms and the tradeoff analysis of expressiveness and computational properties for the spatial DLs