1,721,014 research outputs found
Comparison of Coca-Cola and Kofola in term of additional substances
No full textHOMOLA, Martin. Comparison of Coca-Cola and Kofola in term of additional substances. Praha: The university of economics, The faculty of business administration, The department of management, 2009. 42 s. The aim of this task is a characterization of additional substances, an examination of the influence of Coca-Cola and Kofola on human's health, a discovery of these beverages popularity and a reference on health's hazards resulting from theirs repeated consummation
Contextualized Knowledge Repositories for the Semantic Web
Full text linkWe propose Contextualized Knowledge Repository (CKR): an adaptation of one of the well studied logics of context in AI for the Semantic Web. A CKR is composed of a set of DL knowledge bases, which are embedded in a context by a set of qualifying attributes (time, space, topic, etc.) specifying the boundaries within which the knowledge base is assumed to be true. Contexts of a CKR are organized by a hierarchical coverage relation, which enables an effective representation of knowledge and a flexible method for its reuse between the contexts. The paper defines syntax and semantics for CKR; shows that concept satisfiability and subsumption are decidable with the complexity upper bound of 2NExpTime, and finally it provides a sound and complete Natural Deduction calculus for CKR
Towards Distributed Tableaux Reasoning Procedure for DDL with Increased Subsumption Propagation between Remote Ontologies
No full textDistributed Description Logics (DDL) enable reasoning with multiple ontologies interconnected by direc- tional semantic mapping. In DDL semantic mapping is indicated by so called bridge rules. There are two kinds: into- and onto-bridge rules. Mappings between concepts allow subsumption to propagate from one ontology to another. However, in some cases, espe- cially when more than two local ontologies are involved, subsumption does not always propagate as we would expect. In a recent study, an adjusted se- mantics has been introduced that is able to cope with more complex scenarios. In particular, subsumption propagates along chains of several bridge rules under this new semantics. This study makes use of so called compositional consistency requirement that has been employed before in Package-based description logics. While the results concerning subsumption propaga- tion under the adjusted semantics are encouraging, we show in this paper that this semantics also has drawbacks. In certain situations it violates the di- rectionality principle. We propose a weaker version of the semantics in this paper that is able to cope with chains of onto-bridge rules but it is not able to deal with chains of into-bridge rules. Furthermore we provide a sound and complete tableaux reasoning algorithm for this semantics
Contextual Representation and Reasoning with Description Logics
Full text linkDespite most of the information available in the Semantic Web (SW) is context dependent, there is a lack of mechanism to qualify knowledge with the context in which it is supposed to hold. In the current practice, contextual information is often crafted in the ontology identifier or in the annotations, non of which affects reasoning. Extensions of the SW languages with specific mechanisms that allow to qualify knowledge, e.g., w.r.t. its provenance or w.r.t. time and events, were proposed, however, a widely accepted approach has not yet been reached. We propose a framework called Contextualized Knowledge Repository (CKR), build on top of the expressive description logic SROIQ. A CKR knowledge base is composed of DL knowledge bases, called contexts, each qualified by a set of contextual attributes that specify the boundaries within which the knowledge base is assumed to be true. Contexts are organized by a hierarchical coverage relation that regulates the propagation of knowledge between them. The paper defines the syntax and semantics of CKR; shows that concept satisfiability and subsumption are decidable with the complexity upper bound of 2NEXPTIME (i.e., same as for SROIQ); and finally it provides a sound and complete Natural Deduction calculus that characterizes the propagation of knowledge between contexts
Practising Web Design Essentials by Iterative Blog Development within a Community Portal
No full textFollowing constructionism and the learning by doing approach of Papert in our university web design course students are given the task of building a personal blogs. Students thus practice selected Web technologies. The task is supported by a dedicated web-based integrated development environment. Their blogs are interconnected and communication is available. Students are also encouraged to publish relevant articles on their blogs. We have observed competitiveness boosting, experience exchange, and overall increase of involvement with the course. Our experience suggests improved quality of learning to the benefit of our students
Taking Advantage of Web 2.0 in Organized Education (A Survey)
No full textReports on using Web 2.0 and Social web technology and tools in education appear lately with increasing frequency year after year. Applications of blogging, wikis, social bookmarking and tagging, online communities, podcasting and more were reported. The benefits observed in connection with these new methods include: improved motivation, and quality of learning, development of analytical thinking, collaboration, teamwork, and communication skills. The second part of this work draws conclusions on methodological issues. Blogs seem to be best suited for subjective organization and reflection upon the acquired knowledge. Wikis seem to be well suited for collaborative organization of knowledge. Social bookmarking was used with success for organization of resources of various kinds. The blended learning approach seems to be the most effective way to include these activities in higher education. These tools bring a particular value into those fields of study where open ended discussion and competing opinions are valued, e.g., social sciences, but this is not a rule. Students` activities with these tools provide valuable source of assessment, however not only content contributed by individual students but also frequency and periodicity should take part in the evaluation
Towards Formal Comparison of Ontology Linking, Mapping and Importing
No full textMultiple distributed and modular ontology representation frameworks
have recently appeared. They typically extend Description Logics (DL),
with new constructs to represent relations between entities across
several ontologies. Three kinds of constructs appear in the
literature: link properties, found in E -connections, semantic
mapping, found in Distributed Description Logics (DDL), and semantic
imports, used in Package-based Description Logics (P-DL). In this
work, we aim towards formal comparison of the expressive power of
these frameworks, and thus also the ontology combination paradigms
that they instantiate. Reduction from DDL to E-connections is already
known. We present two new reductions, from P-DL to DDL and vice versa.
These results show that there are similarities between these
frameworks. However, due to the fact that none of the reductions is
unconditional, it cannot be claimed that any of the three approaches
is strictly more expressive than another
Towards an “Intelligent” Tagging Tool for Blogs
No full textTagging allows people to effectively organize web resources such as images, bookmarks or blog articles. Things are found easier by browsing tag clouds relying on the tags that have been assigned before. The success is by large determined by the quality and relevance of tags assigned to content – and so it is dependent on people who do the tagging. We investigate mental processes that underlie tagging. In order to improve quality of tagging, we provide guidelines for users of tagging systems and in addition we suggest features that an “intelligent” tagging tool should bear in order to facilitate the tagging process
ExpTime Reasoning for Contextualized ALC
No full textThe combination of often heterogeneous and contradicting knowledge sources in the Semantic Web demands for methods to represent and reason with a notion of context. Among context representation frameworks, Contextualized Knowledge Repository (CKR) is a novel proposal grounded in the well-studied AI theories of context and aims at bringing the advantages of contextual representation to the Semantic Web. In this paper we show that reasoning in ALC-based CKR is decidable and EXPTIME-complete. The result is presented trough a reduction from ALC-based CKRs to ALCO(t) knowledge bases. This result is important, because it shows that the addition of the contextual layer does not come at the cost of increased complexity of reasoning
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