Undecidability of the unification and admissibility problems for modal and description logics

We show that the unification problem `is there a substitution instance of a given formula that is provable in a given logic?' is undecidable for basic modal logics K and K4 extended with the universal modality. It follows that the admissibility problem for inference rules is undecidable for these logics as well. These are the first examples of standard decidable modal logics for which the unification and admissibility problems are undecidable. We also prove undecidability of the unification and admissibility problems for K and K4 with at least two modal operators and nominals (instead of the universal modality), thereby showing that these problems are undecidable for basic hybrid logics. Recently, unification has been introduced as an important reasoning service for description logics. The undecidability proof for K with nominals can be used to show the undecidability of unification for boolean description logics with nominals (such as ALCO and SHIQO). The undecidability proof for K with the universal modality can be used to show that the unification problem relative to role boxes is undecidable for Boolean description logic with transitive roles, inverse roles, and role hierarchies (such as SHI and SHIQ)

Temporalising OWL 2 QL

We design a temporal description logic, TQL, that extends the standard ontology language OWL2QL, provides basic means for temporal conceptual modelling and ensures first-order rewritability of conjunctive queries for suitably defined data instances with validity time

PENGALAMAN SEXTING PEREMPUAN MUDA DI INDONESIA DALAM KACAMATA STANDPOINT THEORY

ABSTRACT   Sexting is the activity of sending sexually charged messages, whether in the form of photos, videos, or even short messages, carried out via digital media. Sexting activities are usually carried out by male and female couples who are in a romantic relationship. In this context, sexting is done to maintain the quality of the relationship and fulfill the partner's sexual needs. However, there is an imbalance of power between women and men involved in sexting, where women are vulnerable to finding themselves in a disadvantageous position compared to men. Through the perspective of standpoint theory, the experience of women as a marginalized group in sexting activities is an important experience to explore. In standpoint theory, those in marginalized positions are considered to have strong objectivity, so the search for knowledge according to this theory should start from these marginalized groups. Through in-depth interviews with informants, this research found that women are in an inferior position when sexting with men. The informants' experiences showed that male partners were forced to engage in sexting, threatened with sharing sexting content, threatened with the end of the relationship, and felt that sexting was more beneficial for men than women. This research concludes that through the lens of standpoint theory, women do feel injustice in sexting activities with male partners, but still do it in order to maintain their relationship through coercion and avoid bad consequences such as the distribution of sexts.   Keywords : Sexting; Standpoint Theory; Women; Dominatio

Sound and fury in colonial Australia: the search for the convict voice, 1800-1840

This thesis uses an aural analysis of penal-era Australia to enliven, and unsettle, discussion of convict subjectivity within penal-era historiography. The ‘search for the convict voice’, the quest to discover something of the inner-lives of figures that have transfixed Australians for generations, is expanded as well as complicated by an analysis of the sounds of penal life. By reimagining the soundscapes of penal society as complex conglomerations of sounds and noises, voices, conversations, screams, grunts, groans and silences, this thesis enlarges our conception of what a convict voice is, and where best to search for its most genuine expression. The convict voices that form this thesis are part of the story of Australia’s penal, legal and social evolution. As such, they are enduring and permanent, and their legacy can be seen in the development of Australia’s colonial institutions, not in opposition, or contradiction, to such developments. The aim of this thesis is to use aural history to show how convict language and noise, despite the restrictions placed on it by the processes of legal argument, corporal punishment or forced garrulity or silence, was a part of the very fabric of the penal system. The convict voices that emerge from this thesis are forged within, and therefore form an indelible part of, the very processes that created a distinctive Australian society

Temporal description logic for ontology-based data access

Our aim is to investigate ontology-based data access over temporal data with validity time and ontologies capable of temporal conceptual modelling. To this end, we design a temporal description logic, TQL, that extends the standard ontology language OWL2QL, provides basic means for temporal conceptual modelling and ensures first-order rewritability of conjunctive queries for suitably defined data instances with validity time

The combined approach to ontology-based data access

The use of ontologies for accessing data is one of the most exciting new applications of description logics in databases and other information systems. A realistic way of realising sufficiently scalable ontology- based data access in practice is by reduction to querying relational databases. In this paper, we describe the combined approach, which incorporates the information given by the ontology into the data and employs query rewriting to eliminate spurious answers. We illustrate this approach for ontologies given in the DL-Lite family of description logics and briefly discuss the results obtained for the EL family

Query inseparability by games

We investigate conjunctive query inseparability of description logic knowledge bases (KBs) with respect to a given signature, a fundamental problem for KB versioning, module extraction, forgetting and knowledge exchange. We develop a game-theoretic technique for checking query inseparability of KBs expressed in fragments of Horn-ALCHI, and show a number of complexity results ranging from P to ExpTime and 2ExpTime. We also employ our results to resolve two major open problems for OWL 2 QL by showing that TBox query inseparability and the membership problem for universal UCQ-solutions in knowledge exchange are both ExpTime-complete for combined complexity

Combined FO rewritability for conjunctive query answering in DL-Lite

Standard description logic (DL) reasoning services such as satisfiability and subsumption mainly aim to support TBox design. When the design stage is over and the TBox is used in an actual application, it is usually combined with instance data stored in an ABox, and therefore query answering becomes the most importan